-<chapter id="quick-start">
- <title>Quick Start </title>
-
- <para>
- In this section, we will test the system by indexing a small set of sample
- GILS records that are included with the software distribution. Go to the
- <literal>test/gils</literal> subdirectory of the distribution archive.
- There you will find a configuration
- file named <literal>zebra.cfg</literal> with the following contents:
-
- <screen>
- # Where are the YAZ tables located.
- profilePath: ../../../yaz/tab ../../tab
-
- # Files that describe the attribute sets supported.
- attset: bib1.att
- attset: gils.att
- </screen>
- </para>
-
- <para>
- Now, edit the file and set <literal>profilePath</literal> to the path of the
- YAZ profile tables (sub directory <literal>tab</literal> of the YAZ
- distribution archive).
- </para>
-
- <para>
- The 48 test records are located in the sub directory
- <literal>records</literal>. To index these, type:
-
- <screen>
- $ ../../index/zebraidx -t grs.sgml update records
- </screen>
- </para>
-
- <para>
- In the command above the option <literal>-t</literal> specified the record
- type — in this case <literal>grs.sgml</literal>.
- The word <literal>update</literal> followed
- by a directory root updates all files below that directory node.
- </para>
-
- <para>
- If your indexing command was successful, you are now ready to
- fire up a server. To start a server on port 2100, type:
-
- <screen>
- $ ../../index/zebrasrv tcp:@:2100
- </screen>
-
- </para>
-
- <para>
- The Zebra index that you have just created has a single database
- named <literal>Default</literal>.
- The database contains records structured according to
- the GILS profile, and the server will
- return records in either either USMARC, GRS-1, or SUTRS depending
- on what your client asks for.
- </para>
-
- <para>
- To test the server, you can use any Z39.50 client (1992 or later).
- For instance, you can use the demo client that comes with YAZ: Just
- cd to the <literal>client</literal> subdirectory of the YAZ distribution
- and type:
- </para>
- <para>
- <screen>
- $ ./yaz-client tcp:localhost:2100
- </screen>
- </para>
-
- <para>
- When the client has connected, you can type:
- </para>
-
-<para>
-
- <screen>
- Z> find surficial
- Z> show 1
- </screen>
- </para>
-
- <para>
- The default retrieval syntax for the client is USMARC. To try other
- formats for the same record, try:
- </para>
- <para>
- <screen>
- Z>format sutrs
- Z>show 1
- Z>format grs-1
- Z>show 1
- Z>elements B
- Z>show 1
- </screen>
- </para>
-
- <note>
- <para>You may notice that more fields are returned when your
- client requests SUTRS or GRS-1 records. When retrieving GILS records,
- this is normal - not all of the GILS data elements have mappings in
- the USMARC record format.
- </para>
- </note>
- <para>
- If you've made it this far, there's a good chance that
- you've got through the compilation OK.
- </para>
-
-</chapter>
-
-<chapter id="administration">
- <title>Administrating Zebra</title>
-
- <para>
- Unlike many simpler retrieval systems, Zebra supports safe, incremental
- updates to an existing index.
- </para>
-
- <para>
- Normally, when Zebra modifies the index it reads a number of records
- that you specify.
- Depending on your specifications and on the contents of each record
- one the following events take place for each record:
- <variablelist>
-
- <varlistentry>
- <term>Insert</term>
- <listitem>
- <para>
- The record is indexed as if it never occurred before.
- Either the Zebra system doesn't know how to identify the record or
- Zebra can identify the record but didn't find it to be already indexed.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Modify</term>
- <listitem>
- <para>
- The record has already been indexed. In this case
- either the contents of the record or the location (file) of the record
- indicates that it has been indexed before.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Delete</term>
- <listitem>
- <para>
- The record is deleted from the index. As in the
- update-case it must be able to identify the record.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
-
- <para>
- Please note that in both the modify- and delete- case the Zebra
- indexer must be able to generate a unique key that identifies the record in
- question (more on this below).
- </para>
-
- <para>
- To administrate the Zebra retrieval system, you run the
- <literal>zebraidx</literal> program.
- This program supports a number of options which are preceded by a dash,
- and a few commands (not preceded by dash).
-</para>
-
- <para>
- Both the Zebra administrative tool and the Z39.50 server share a
- set of index files and a global configuration file. The
- name of the configuration file defaults to <literal>zebra.cfg</literal>.
- The configuration file includes specifications on how to index
- various kinds of records and where the other configuration files
- are located. <literal>zebrasrv</literal> and <literal>zebraidx</literal>
- <emphasis>must</emphasis> be run in the directory where the
- configuration file lives unless you indicate the location of the
- configuration file by option <literal>-c</literal>.
- </para>
-
- <sect1 id="record-types">
- <title>Record Types</title>
-
- <para>
- Indexing is a per-record process, in which either insert/modify/delete
- will occur. Before a record is indexed search keys are extracted from
- whatever might be the layout the original record (sgml,html,text, etc..).
- The Zebra system currently supports two fundamantal types of records:
- structured and simple text.
- To specify a particular extraction process, use either the
- command line option <literal>-t</literal> or specify a
- <literal>recordType</literal> setting in the configuration file.
- </para>
-
- </sect1>
-
- <sect1 id="configuration-file">
- <title>The Zebra Configuration File</title>
-
- <para>
- The Zebra configuration file, read by <literal>zebraidx</literal> and
- <literal>zebrasrv</literal> defaults to <literal>zebra.cfg</literal>
- unless specified by <literal>-c</literal> option.
- </para>
-
- <para>
- You can edit the configuration file with a normal text editor.
- parameter names and values are seperated by colons in the file. Lines
- starting with a hash sign (<literal>#</literal>) are
- treated as comments.
- </para>
-
- <para>
- If you manage different sets of records that share common
- characteristics, you can organize the configuration settings for each
- type into "groups".
- When <literal>zebraidx</literal> is run and you wish to address a
- given group you specify the group name with the <literal>-g</literal>
- option.
- In this case settings that have the group name as their prefix
- will be used by <literal>zebraidx</literal>.
- If no <literal>-g</literal> option is specified, the settings
- without prefix are used.
- </para>
-
- <para>
- In the configuration file, the group name is placed before the option
- name itself, separated by a dot (.). For instance, to set the record type
- for group <literal>public</literal> to <literal>grs.sgml</literal>
- (the SGML-like format for structured records) you would write:
- </para>
-
- <para>
- <screen>
- public.recordType: grs.sgml
- </screen>
- </para>
-
- <para>
- To set the default value of the record type to <literal>text</literal>
- write:
- </para>
-
- <para>
- <screen>
- recordType: text
- </screen>
- </para>
-
- <para>
- The available configuration settings are summarized below. They will be
- explained further in the following sections.
- </para>
-
- <para>
- <variablelist>
-
- <varlistentry>
- <term>
- <emphasis>group</emphasis>
- .recordType[<emphasis>.name</emphasis>]
- </term>
- <listitem>
- <para>
- Specifies how records with the file extension
- <emphasis>name</emphasis> should be handled by the indexer.
- This option may also be specified as a command line option
- (<literal>-t</literal>). Note that if you do not specify a
- <emphasis>name</emphasis>, the setting applies to all files.
- In general, the record type specifier consists of the elements (each
- element separated by dot), <emphasis>fundamental-type</emphasis>,
- <emphasis>file-read-type</emphasis> and arguments. Currently, two
- fundamental types exist, <literal>text</literal> and
- <literal>grs</literal>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis>group</emphasis>.recordId</term>
- <listitem>
- <para>
- Specifies how the records are to be identified when updated. See
- section <xref linkend="locating-records"/>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis>group</emphasis>.database</term>
- <listitem>
- <para>
- Specifies the Z39.50 database name.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis>group</emphasis>.storeKeys</term>
- <listitem>
- <para>
- Specifies whether key information should be saved for a given
- group of records. If you plan to update/delete this type of
- records later this should be specified as 1; otherwise it
- should be 0 (default), to save register space. See section
- <xref linkend="file-ids"/>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis>group</emphasis>.storeData</term>
- <listitem>
- <para>
- Specifies whether the records should be stored internally
- in the Zebra system files.
- If you want to maintain the raw records yourself,
- this option should be false (0).
- If you want Zebra to take care of the records for you, it
- should be true(1).
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>register</term>
- <listitem>
- <para>
- Specifies the location of the various register files that Zebra uses
- to represent your databases. See section
- <xref linkend="register-location"/>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>shadow</term>
- <listitem>
- <para>
- Enables the <emphasis>safe update</emphasis> facility of Zebra, and
- tells the system where to place the required, temporary files.
- See section
- <xref linkend="shadow-registers"/>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>lockDir</term>
- <listitem>
- <para>
- Directory in which various lock files are stored.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>keyTmpDir</term>
- <listitem>
- <para>
- Directory in which temporary files used during zebraidx' update
- phase are stored.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>setTmpDir</term>
- <listitem>
- <para>
- Specifies the directory that the server uses for temporary result sets.
- If not specified <literal>/tmp</literal> will be used.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>profilePath</term>
- <listitem>
- <para>
- Specifies the location of profile specification files.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>attset</term>
- <listitem>
- <para>
- Specifies the filename(s) of attribute set files for use in
- searching. At least the Bib-1 set should be loaded
- (<literal>bib1.att</literal>).
- The <literal>profilePath</literal> setting is used to look for
- the specified files.
- See section <xref linkend="attset-files"/>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>memMax</term>
- <listitem>
- <para>
- Specifies size of internal memory to use for the zebraidx program. The
- amount is given in megabytes - default is 4 (4 MB).
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
-
- </sect1>
-
- <sect1 id="locating-records">
- <title>Locating Records</title>
-
- <para>
- The default behaviour of the Zebra system is to reference the
- records from their original location, i.e. where they were found when you
- ran <literal>zebraidx</literal>.
- That is, when a client wishes to retrieve a record
- following a search operation, the files are accessed from the place
- where you originally put them - if you remove the files (without
- running <literal>zebraidx</literal> again, the client
- will receive a diagnostic message.
- </para>
-
- <para>
- If your input files are not permanent - for example if you retrieve
- your records from an outside source, or if they were temporarily
- mounted on a CD-ROM drive,
- you may want Zebra to make an internal copy of them. To do this,
- you specify 1 (true) in the <literal>storeData</literal> setting. When
- the Z39.50 server retrieves the records they will be read from the
- internal file structures of the system.
- </para>
-
- </sect1>
-
- <sect1 id="simple-indexing">
- <title>Indexing with no Record IDs (Simple Indexing)</title>
-
- <para>
- If you have a set of records that are not expected to change over time
- you may can build your database without record IDs.
- This indexing method uses less space than the other methods and
- is simple to use.
- </para>
-
- <para>
- To use this method, you simply omit the <literal>recordId</literal> entry
- for the group of files that you index. To add a set of records you use
- <literal>zebraidx</literal> with the <literal>update</literal> command. The
- <literal>update</literal> command will always add all of the records that it
- encounters to the index - whether they have already been indexed or
- not. If the set of indexed files change, you should delete all of the
- index files, and build a new index from scratch.
- </para>
-
- <para>
- Consider a system in which you have a group of text files called
- <literal>simple</literal>.
- That group of records should belong to a Z39.50 database called
- <literal>textbase</literal>.
- The following <literal>zebra.cfg</literal> file will suffice:
- </para>
- <para>
-
- <screen>
- profilePath: /usr/local/yaz
- attset: bib1.att
- simple.recordType: text
- simple.database: textbase
- </screen>
+ <chapter id="administration">
+ <title>Administrating &zebra;</title>
+ <!-- ### It's a bit daft that this chapter (which describes half of
+ the configuration-file formats) is separated from
+ "recordmodel-grs.xml" (which describes the other half) by the
+ instructions on running zebraidx and zebrasrv. Some careful
+ re-ordering is required here.
+ -->
- </para>
-
- <para>
- Since the existing records in an index can not be addressed by their
- IDs, it is impossible to delete or modify records when using this method.
- </para>
-
- </sect1>
-
- <sect1 id="file-ids">
- <title>Indexing with File Record IDs</title>
-
- <para>
- If you have a set of files that regularly change over time: Old files
- are deleted, new ones are added, or existing files are modified, you
- can benefit from using the <emphasis>file ID</emphasis>
- indexing methodology.
- Examples of this type of database might include an index of WWW
- resources, or a USENET news spool area.
- Briefly speaking, the file key methodology uses the directory paths
- of the individual records as a unique identifier for each record.
- To perform indexing of a directory with file keys, again, you specify
- the top-level directory after the <literal>update</literal> command.
- The command will recursively traverse the directories and compare
- each one with whatever have been indexed before in that same directory.
- If a file is new (not in the previous version of the directory) it
- is inserted into the registers; if a file was already indexed and
- it has been modified since the last update, the index is also
- modified; if a file has been removed since the last
- visit, it is deleted from the index.
- </para>
-
- <para>
- The resulting system is easy to administrate. To delete a record you
- simply have to delete the corresponding file (say, with the
- <literal>rm</literal> command). And to add records you create new
- files (or directories with files). For your changes to take effect
- in the register you must run <literal>zebraidx update</literal> with
- the same directory root again. This mode of operation requires more
- disk space than simpler indexing methods, but it makes it easier for
- you to keep the index in sync with a frequently changing set of data.
- If you combine this system with the <emphasis>safe update</emphasis>
- facility (see below), you never have to take your server offline for
- maintenance or register updating purposes.
- </para>
-
- <para>
- To enable indexing with pathname IDs, you must specify
- <literal>file</literal> as the value of <literal>recordId</literal>
- in the configuration file. In addition, you should set
- <literal>storeKeys</literal> to <literal>1</literal>, since the Zebra
- indexer must save additional information about the contents of each record
- in order to modify the indices correctly at a later time.
- </para>
-
- <para>
- For example, to update records of group <literal>esdd</literal>
- located below
- <literal>/data1/records/</literal> you should type:
- <screen>
- $ zebraidx -g esdd update /data1/records
- </screen>
- </para>
-
- <para>
- The corresponding configuration file includes:
- <screen>
- esdd.recordId: file
- esdd.recordType: grs.sgml
- esdd.storeKeys: 1
- </screen>
- </para>
-
- <note>
- <para>You cannot start out with a group of records with simple
- indexing (no record IDs as in the previous section) and then later
- enable file record Ids. Zebra must know from the first time that you
- index the group that
- the files should be indexed with file record IDs.
- </para>
- </note>
-
- <para>
- You cannot explicitly delete records when using this method (using the
- <literal>delete</literal> command to <literal>zebraidx</literal>. Instead
- you have to delete the files from the file system (or move them to a
- different location)
- and then run <literal>zebraidx</literal> with the
- <literal>update</literal> command.
- </para>
-</sect1>
-
- <sect1 id="generic-ids">
- <title>Indexing with General Record IDs</title>
-
- <para>
- When using this method you construct an (almost) arbritrary, internal
- record key based on the contents of the record itself and other system
- information. If you have a group of records that explicitly associates
- an ID with each record, this method is convenient. For example, the
- record format may contain a title or a ID-number - unique within the group.
- In either case you specify the Z39.50 attribute set and use-attribute
- location in which this information is stored, and the system looks at
- that field to determine the identity of the record.
- </para>
-
<para>
- As before, the record ID is defined by the <literal>recordId</literal>
- setting in the configuration file. The value of the record ID specification
- consists of one or more tokens separated by whitespace. The resulting
- ID is represented in the index by concatenating the tokens and
- separating them by ASCII value (1).
+ Unlike many simpler retrieval systems, &zebra; supports safe, incremental
+ updates to an existing index.
</para>
-
+
<para>
- There are three kinds of tokens:
+ Normally, when &zebra; modifies the index it reads a number of records
+ that you specify.
+ Depending on your specifications and on the contents of each record
+ one the following events take place for each record:
<variablelist>
-
+
<varlistentry>
- <term>Internal record info</term>
+ <term>Insert</term>
<listitem>
<para>
- The token refers to a key that is
- extracted from the record. The syntax of this token is
- <literal>(</literal> <emphasis>set</emphasis> <literal>,</literal>
- <emphasis>use</emphasis> <literal>)</literal>,
- where <emphasis>set</emphasis> is the
- attribute set name <emphasis>use</emphasis> is the
- name or value of the attribute.
+ The record is indexed as if it never occurred before.
+ Either the &zebra; system doesn't know how to identify the record or
+ &zebra; can identify the record but didn't find it to be already indexed.
</para>
</listitem>
</varlistentry>
<varlistentry>
- <term>System variable</term>
+ <term>Modify</term>
<listitem>
<para>
- The system variables are preceded by
-
- <screen>
- $
- </screen>
- and immediately followed by the system variable name, which
- may one of
- <variablelist>
-
- <varlistentry>
- <term>group</term>
- <listitem>
- <para>
- Group name.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>database</term>
- <listitem>
- <para>
- Current database specified.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>type</term>
- <listitem>
- <para>
- Record type.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
+ The record has already been indexed.
+ In this case either the contents of the record or the location
+ (file) of the record indicates that it has been indexed before.
</para>
</listitem>
</varlistentry>
<varlistentry>
- <term>Constant string</term>
+ <term>Delete</term>
<listitem>
<para>
- A string used as part of the ID — surrounded
- by single- or double quotes.
+ The record is deleted from the index. As in the
+ update-case it must be able to identify the record.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
-
- <para>
- For instance, the sample GILS records that come with the Zebra
- distribution contain a unique ID in the data tagged Control-Identifier.
- The data is mapped to the Bib-1 use attribute Identifier-standard
- (code 1007). To use this field as a record id, specify
- <literal>(bib1,Identifier-standard)</literal> as the value of the
- <literal>recordId</literal> in the configuration file.
- If you have other record types that uses the same field for a
- different purpose, you might add the record type
- (or group or database name) to the record id of the gils
- records as well, to prevent matches with other types of records.
- In this case the recordId might be set like this:
-
- <screen>
- gils.recordId: $type (bib1,Identifier-standard)
- </screen>
-
- </para>
-
- <para>
- (see section <xref linkend="data-model"/>
- for details of how the mapping between elements of your records and
- searchable attributes is established).
- </para>
-
- <para>
- As for the file record ID case described in the previous section,
- updating your system is simply a matter of running
- <literal>zebraidx</literal>
- with the <literal>update</literal> command. However, the update with general
- keys is considerably slower than with file record IDs, since all files
- visited must be (re)read to discover their IDs.
- </para>
-
- <para>
- As you might expect, when using the general record IDs
- method, you can only add or modify existing records with the
- <literal>update</literal> command.
- If you wish to delete records, you must use the,
- <literal>delete</literal> command, with a directory as a parameter.
- This will remove all records that match the files below that root
- directory.
- </para>
-
- </sect1>
-
- <sect1 id="register-location">
- <title>Register Location</title>
-
- <para>
- Normally, the index files that form dictionaries, inverted
- files, record info, etc., are stored in the directory where you run
- <literal>zebraidx</literal>. If you wish to store these, possibly large,
- files somewhere else, you must add the <literal>register</literal>
- entry to the <literal>zebra.cfg</literal> file.
- Furthermore, the Zebra system allows its file
- structures to span multiple file systems, which is useful for
- managing very large databases.
- </para>
-
+
<para>
- The value of the <literal>register</literal> setting is a sequence
- of tokens. Each token takes the form:
-
- <screen>
- <emphasis>dir</emphasis><literal>:</literal><emphasis>size</emphasis>.
- </screen>
-
- The <emphasis>dir</emphasis> specifies a directory in which index files
- will be stored and the <emphasis>size</emphasis> specifies the maximum
- size of all files in that directory. The Zebra indexer system fills
- each directory in the order specified and use the next specified
- directories as needed.
- The <emphasis>size</emphasis> is an integer followed by a qualifier
- code, <literal>M</literal> for megabytes,
- <literal>k</literal> for kilobytes.
+ Please note that in both the modify- and delete- case the &zebra;
+ indexer must be able to generate a unique key that identifies the record
+ in question (more on this below).
</para>
-
+
<para>
- For instance, if you have allocated two disks for your register, and
- the first disk is mounted
- on <literal>/d1</literal> and has 200 Mb of free space and the
- second, mounted on <literal>/d2</literal> has 300 Mb, you could
- put this entry in your configuration file:
-
- <screen>
- register: /d1:200M /d2:300M
- </screen>
-
+ To administrate the &zebra; retrieval system, you run the
+ <literal>zebraidx</literal> program.
+ This program supports a number of options which are preceded by a dash,
+ and a few commands (not preceded by dash).
</para>
-
+
<para>
- Note that Zebra does not verify that the amount of space specified is
- actually available on the directory (file system) specified - it is
- your responsibility to ensure that enough space is available, and that
- other applications do not attempt to use the free space. In a large
- production system, it is recommended that you allocate one or more
- filesystem exclusively to the Zebra register files.
+ Both the &zebra; administrative tool and the &acro.z3950; server share a
+ set of index files and a global configuration file.
+ The name of the configuration file defaults to
+ <literal>zebra.cfg</literal>.
+ The configuration file includes specifications on how to index
+ various kinds of records and where the other configuration files
+ are located. <literal>zebrasrv</literal> and <literal>zebraidx</literal>
+ <emphasis>must</emphasis> be run in the directory where the
+ configuration file lives unless you indicate the location of the
+ configuration file by option <literal>-c</literal>.
</para>
-
- </sect1>
-
- <sect1 id="shadow-registers">
- <title>Safe Updating - Using Shadow Registers</title>
-
- <sect2>
- <title>Description</title>
-
- <para>
- The Zebra server supports <emphasis>updating</emphasis> of the index
- structures. That is, you can add, modify, or remove records from
- databases managed by Zebra without rebuilding the entire index.
- Since this process involves modifying structured files with various
- references between blocks of data in the files, the update process
- is inherently sensitive to system crashes, or to process interruptions:
- Anything but a successfully completed update process will leave the
- register files in an unknown state, and you will essentially have no
- recourse but to re-index everything, or to restore the register files
- from a backup medium.
- Further, while the update process is active, users cannot be
- allowed to access the system, as the contents of the register files
- may change unpredictably.
- </para>
-
- <para>
- You can solve these problems by enabling the shadow register system in
- Zebra.
- During the updating procedure, <literal>zebraidx</literal> will temporarily
- write changes to the involved files in a set of "shadow
- files", without modifying the files that are accessed by the
- active server processes. If the update procedure is interrupted by a
- system crash or a signal, you simply repeat the procedure - the
- register files have not been changed or damaged, and the partially
- written shadow files are automatically deleted before the new updating
- procedure commences.
- </para>
-
+
+ <sect1 id="record-types">
+ <title>Record Types</title>
+
<para>
- At the end of the updating procedure (or in a separate operation, if
- you so desire), the system enters a "commit mode". First,
- any active server processes are forced to access those blocks that
- have been changed from the shadow files rather than from the main
- register files; the unmodified blocks are still accessed at their
- normal location (the shadow files are not a complete copy of the
- register files - they only contain those parts that have actually been
- modified). If the commit process is interrupted at any point during the
- commit process, the server processes will continue to access the
- shadow files until you can repeat the commit procedure and complete
- the writing of data to the main register files. You can perform
- multiple update operations to the registers before you commit the
- changes to the system files, or you can execute the commit operation
- at the end of each update operation. When the commit phase has
- completed successfully, any running server processes are instructed to
- switch their operations to the new, operational register, and the
- temporary shadow files are deleted.
+ Indexing is a per-record process, in which either insert/modify/delete
+ will occur. Before a record is indexed search keys are extracted from
+ whatever might be the layout the original record (sgml,html,text, etc..).
+ The &zebra; system currently supports two fundamental types of records:
+ structured and simple text.
+ To specify a particular extraction process, use either the
+ command line option <literal>-t</literal> or specify a
+ <literal>recordType</literal> setting in the configuration file.
</para>
-
- </sect2>
-
- <sect2>
- <title>How to Use Shadow Register Files</title>
-
+
+ </sect1>
+
+ <sect1 id="zebra-cfg">
+ <title>The &zebra; Configuration File</title>
+
<para>
- The first step is to allocate space on your system for the shadow
- files.
- You do this by adding a <literal>shadow</literal> entry to the
- <literal>zebra.cfg</literal> file.
- The syntax of the <literal>shadow</literal> entry is exactly the
- same as for the <literal>register</literal> entry
- (see section <xref linkend="register-location"/>).
- The location of the shadow area should be
- <emphasis>different</emphasis> from the location of the main register
- area (if you have specified one - remember that if you provide no
- <literal>register</literal> setting, the default register area is the
- working directory of the server and indexing processes).
+ The &zebra; configuration file, read by <literal>zebraidx</literal> and
+ <literal>zebrasrv</literal> defaults to <literal>zebra.cfg</literal>
+ unless specified by <literal>-c</literal> option.
</para>
-
+
<para>
- The following excerpt from a <literal>zebra.cfg</literal> file shows
- one example of a setup that configures both the main register
- location and the shadow file area.
- Note that two directories or partitions have been set aside
- for the shadow file area. You can specify any number of directories
- for each of the file areas, but remember that there should be no
- overlaps between the directories used for the main registers and the
- shadow files, respectively.
+ You can edit the configuration file with a normal text editor.
+ parameter names and values are separated by colons in the file. Lines
+ starting with a hash sign (<literal>#</literal>) are
+ treated as comments.
</para>
+
<para>
-
- <screen>
- register: /d1:500M
-
- shadow: /scratch1:100M /scratch2:200M
- </screen>
-
+ If you manage different sets of records that share common
+ characteristics, you can organize the configuration settings for each
+ type into "groups".
+ When <literal>zebraidx</literal> is run and you wish to address a
+ given group you specify the group name with the <literal>-g</literal>
+ option.
+ In this case settings that have the group name as their prefix
+ will be used by <literal>zebraidx</literal>.
+ If no <literal>-g</literal> option is specified, the settings
+ without prefix are used.
</para>
-
+
<para>
- When shadow files are enabled, an extra command is available at the
- <literal>zebraidx</literal> command line.
- In order to make changes to the system take effect for the
- users, you'll have to submit a "commit" command after a
- (sequence of) update operation(s).
- You can ask the indexer to commit the changes immediately
- after the update operation:
+ In the configuration file, the group name is placed before the option
+ name itself, separated by a dot (.). For instance, to set the record type
+ for group <literal>public</literal> to <literal>grs.sgml</literal>
+ (the &acro.sgml;-like format for structured records) you would write:
</para>
-
+
<para>
-
<screen>
- $ zebraidx update /d1/records update /d2/more-records commit
+ public.recordType: grs.sgml
</screen>
-
</para>
-
+
<para>
- Or you can execute multiple updates before committing the changes:
+ To set the default value of the record type to <literal>text</literal>
+ write:
</para>
-
+
<para>
-
<screen>
- $ zebraidx -g books update /d1/records update /d2/more-records
- $ zebraidx -g fun update /d3/fun-records
- $ zebraidx commit
+ recordType: text
</screen>
-
- </para>
-
- <para>
- If one of the update operations above had been interrupted, the commit
- operation on the last line would fail: <literal>zebraidx</literal>
- will not let you commit changes that would destroy the running register.
- You'll have to rerun all of the update operations since your last
- commit operation, before you can commit the new changes.
</para>
-
- <para>
- Similarly, if the commit operation fails, <literal>zebraidx</literal>
- will not let you start a new update operation before you have
- successfully repeated the commit operation.
- The server processes will keep accessing the shadow files rather
- than the (possibly damaged) blocks of the main register files
- until the commit operation has successfully completed.
- </para>
-
+
<para>
- You should be aware that update operations may take slightly longer
- when the shadow register system is enabled, since more file access
- operations are involved. Further, while the disk space required for
- the shadow register data is modest for a small update operation, you
- may prefer to disable the system if you are adding a very large number
- of records to an already very large database (we use the terms
- <emphasis>large</emphasis> and <emphasis>modest</emphasis>
- very loosely here, since every application will have a
- different perception of size).
- To update the system without the use of the the shadow files,
- simply run <literal>zebraidx</literal> with the <literal>-n</literal>
- option (note that you do not have to execute the
- <emphasis>commit</emphasis> command of <literal>zebraidx</literal>
- when you temporarily disable the use of the shadow registers in
- this fashion.
- Note also that, just as when the shadow registers are not enabled,
- server processes will be barred from accessing the main register
- while the update procedure takes place.
+ The available configuration settings are summarized below. They will be
+ explained further in the following sections.
</para>
-
- </sect2>
-
- </sect1>
-
-</chapter>
-
-<chapter id="zebraidx">
- <title>Running the Maintenance Interface (zebraidx)</title>
-
- <para>
- The following is a complete reference to the command line interface to
- the <literal>zebraidx</literal> application.
- </para>
-
- <para>
- Syntax
-
- <screen>
- $ zebraidx [options] command [directory] ...
- </screen>
-
- Options:
- <variablelist>
-
- <varlistentry>
- <term>-t <replaceable>type</replaceable></term>
- <listitem>
- <para>
- Update all files as <replaceable>type</replaceable>. Currently, the
- types supported are <literal>text</literal> and
- <literal>grs</literal><replaceable>.subtype</replaceable>.
- If no <replaceable>subtype</replaceable> is provided for the GRS
- (General Record Structure) type, the canonical input format
- is assumed (see section <xref linkend="local-representation"/>).
- Generally, it is probably advisable to specify the record types
- in the <literal>zebra.cfg</literal> file (see section
- <xref linkend="record-types"/>), to avoid confusion at
- subsequent updates.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-c <replaceable>config-file</replaceable></term>
- <listitem>
- <para>
- Read the configuration file
- <replaceable>config-file</replaceable> instead of
- <literal>zebra.cfg</literal>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-g <replaceable>group</replaceable></term>
- <listitem>
- <para>
- Update the files according to the group
- settings for <replaceable>group</replaceable> (see section
- <xref linkend="configuration-file"/>).
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-d <replaceable>database</replaceable></term>
- <listitem>
- <para>
- The records located should be associated with the database name
- <replaceable>database</replaceable> for access through the Z39.50 server.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-m <replaceable>mbytes</replaceable></term>
- <listitem>
- <para>
- Use <replaceable>mbytes</replaceable> of megabytes before flushing
- keys to background storage. This setting affects performance when
- updating large databases.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-n</term>
- <listitem>
- <para>
- Disable the use of shadow registers for this operation
- (see section <xref linkend="shadow-registers"/>).
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-s</term>
- <listitem>
- <para>
- Show analysis of the indexing process. The maintenance
- program works in a read-only mode and doesn't change the state
- of the index. This options is very useful when you wish to test a
- new profile.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-V</term>
- <listitem>
- <para>
- Show Zebra version.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-v <replaceable>level</replaceable></term>
- <listitem>
- <para>
- Set the log level to <replaceable>level</replaceable>.
- <replaceable>level</replaceable> should be one of
- <literal>none</literal>, <literal>debug</literal>, and
- <literal>all</literal>.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
-
- <para>
- Commands
- <variablelist>
-
- <varlistentry>
- <term>update <replaceable>directory</replaceable></term>
- <listitem>
- <para>
- Update the register with the files contained in
- <replaceable>directory</replaceable>.
- If no directory is provided, a list of files is read from
- <literal>stdin</literal>.
- See section <xref linkend="administration"/>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>delete <replaceable>directory</replaceable></term>
- <listitem>
- <para>
- Remove the records corresponding to the files found under
- <replaceable>directory</replaceable> from the register.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>commit</term>
- <listitem>
- <para>
- Write the changes resulting from the last <literal>update</literal>
- commands to the register. This command is only available if the use of
- shadow register files is enabled (see section
- <xref linkend="shadow-registers"/>).
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
-
-</chapter>
-<chapter id="server">
- <title>The Z39.50 Server</title>
+ <!--
+ FIXME - Didn't Adam make something to have multiple databases in multiple dirs...
+ -->
- <sect1 id="zebrasrv">
- <title>Running the Z39.50 Server (zebrasrv)</title>
-
- <para>
- <emphasis remap="bf">Syntax</emphasis>
-
- <screen>
- zebrasrv [options] [listener-address ...]
- </screen>
-
- </para>
-
- <para>
- <emphasis remap="bf">Options</emphasis>
- <variablelist>
+ <para>
+ <variablelist>
- <varlistentry>
- <term>-a <replaceable>APDU file</replaceable></term>
- <listitem>
- <para>
- Specify a file for dumping PDUs (for diagnostic purposes).
- The special name "-" sends output to <literal>stderr</literal>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-c <replaceable>config-file</replaceable></term>
- <listitem>
- <para>
- Read configuration information from
- <replaceable>config-file</replaceable>.
- The default configuration is <literal>./zebra.cfg</literal>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-S</term>
- <listitem>
- <para>
- Don't fork on connection requests. This can be useful for
- symbolic-level debugging. The server can only accept a single
- connection in this mode.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-s</term>
- <listitem>
- <para>
- Use the SR protocol.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-z</term>
- <listitem>
- <para>
- Use the Z39.50 protocol (default). These two options complement
- eachother. You can use both multiple times on the same command
- line, between listener-specifications (see below). This way, you
- can set up the server to listen for connections in both protocols
- concurrently, on different local ports.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-l <replaceable>logfile</replaceable></term>
- <listitem>
- <para>
- Specify an output file for the diagnostic messages.
- The default is to write this information to <literal>stderr</literal>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-v <replaceable>log-level</replaceable></term>
- <listitem>
- <para>
- The log level. Use a comma-separated list of members of the set
- {fatal,debug,warn,log,all,none}.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-u <replaceable>username</replaceable></term>
- <listitem>
- <para>
- Set user ID. Sets the real UID of the server process to that of the
- given <replaceable>username</replaceable>.
- It's useful if you aren't comfortable with having the
- server run as root, but you need to start it as such to bind a
- privileged port.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-w <replaceable>working-directory</replaceable></term>
- <listitem>
- <para>
- Change working directory.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-i</term>
- <listitem>
- <para>
- Run under the Internet superserver, <literal>inetd</literal>.
- Make sure you use the logfile option <literal>-l</literal> in
- conjunction with this mode and specify the <literal>-l</literal>
- option before any other options.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-t <replaceable>timeout</replaceable></term>
- <listitem>
- <para>
- Set the idle session timeout (default 60 minutes).
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>-k <replaceable>kilobytes</replaceable></term>
- <listitem>
- <para>
- Set the (approximate) maximum size of
- present response messages. Default is 1024 Kb (1 Mb).
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
-
- <para>
- A <replaceable>listener-address</replaceable> consists of a transport
- mode followed by a colon (:) followed by a listener address.
- The transport mode is either <literal>ssl</literal> or
- <literal>tcp</literal>.
- </para>
+ <varlistentry>
+ <term>
+ <emphasis>group</emphasis>
+ .recordType[<emphasis>.name</emphasis>]:
+ <replaceable>type</replaceable>
+ </term>
+ <listitem>
+ <para>
+ Specifies how records with the file extension
+ <emphasis>name</emphasis> should be handled by the indexer.
+ This option may also be specified as a command line option
+ (<literal>-t</literal>). Note that if you do not specify a
+ <emphasis>name</emphasis>, the setting applies to all files.
+ In general, the record type specifier consists of the elements (each
+ element separated by dot), <emphasis>fundamental-type</emphasis>,
+ <emphasis>file-read-type</emphasis> and arguments. Currently, two
+ fundamental types exist, <literal>text</literal> and
+ <literal>grs</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><emphasis>group</emphasis>.recordId:
+ <replaceable>record-id-spec</replaceable></term>
+ <listitem>
+ <para>
+ Specifies how the records are to be identified when updated. See
+ <xref linkend="locating-records"/>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><emphasis>group</emphasis>.database:
+ <replaceable>database</replaceable></term>
+ <listitem>
+ <para>
+ Specifies the &acro.z3950; database name.
+ <!-- FIXME - now we can have multiple databases in one server. -H -->
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><emphasis>group</emphasis>.storeKeys:
+ <replaceable>boolean</replaceable></term>
+ <listitem>
+ <para>
+ Specifies whether key information should be saved for a given
+ group of records. If you plan to update/delete this type of
+ records later this should be specified as 1; otherwise it
+ should be 0 (default), to save register space.
+ <!-- ### this is the first mention of "register" -->
+ See <xref linkend="file-ids"/>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><emphasis>group</emphasis>.storeData:
+ <replaceable>boolean</replaceable></term>
+ <listitem>
+ <para>
+ Specifies whether the records should be stored internally
+ in the &zebra; system files.
+ If you want to maintain the raw records yourself,
+ this option should be false (0).
+ If you want &zebra; to take care of the records for you, it
+ should be true(1).
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <!-- ### probably a better place to define "register" -->
+ <term>register: <replaceable>register-location</replaceable></term>
+ <listitem>
+ <para>
+ Specifies the location of the various register files that &zebra; uses
+ to represent your databases.
+ See <xref linkend="register-location"/>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>shadow: <replaceable>register-location</replaceable></term>
+ <listitem>
+ <para>
+ Enables the <emphasis>safe update</emphasis> facility of &zebra;, and
+ tells the system where to place the required, temporary files.
+ See <xref linkend="shadow-registers"/>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>lockDir: <replaceable>directory</replaceable></term>
+ <listitem>
+ <para>
+ Directory in which various lock files are stored.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>keyTmpDir: <replaceable>directory</replaceable></term>
+ <listitem>
+ <para>
+ Directory in which temporary files used during zebraidx's update
+ phase are stored.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>setTmpDir: <replaceable>directory</replaceable></term>
+ <listitem>
+ <para>
+ Specifies the directory that the server uses for temporary result sets.
+ If not specified <literal>/tmp</literal> will be used.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>profilePath: <replaceable>path</replaceable></term>
+ <listitem>
+ <para>
+ Specifies a path of profile specification files.
+ The path is composed of one or more directories separated by
+ colon. Similar to <literal>PATH</literal> for UNIX systems.
+ </para>
+ </listitem>
+ </varlistentry>
- <para>
- For TCP, an address has the form
- </para>
+ <varlistentry>
+ <term>modulePath: <replaceable>path</replaceable></term>
+ <listitem>
+ <para>
+ Specifies a path of record filter modules.
+ The path is composed of one or more directories separated by
+ colon. Similar to <literal>PATH</literal> for UNIX systems.
+ The 'make install' procedure typically puts modules in
+ <filename>/usr/local/lib/idzebra-2.0/modules</filename>.
+ </para>
+ </listitem>
+ </varlistentry>
- <para>
+ <varlistentry>
+ <term>index: <replaceable>filename</replaceable></term>
+ <listitem>
+ <para>
+ Defines the filename which holds fields structure
+ definitions. If omitted, the file <filename>default.idx</filename>
+ is read.
+ Refer to <xref linkend="default-idx-file"/> for
+ more information.
+ </para>
+ </listitem>
+ </varlistentry>
- <screen>
- hostname | IP-number [: portnumber]
- </screen>
+ <varlistentry>
+ <term>sortmax: <replaceable>integer</replaceable></term>
+ <listitem>
+ <para>
+ Specifies the maximum number of records that will be sorted
+ in a result set. If the result set contains more than
+ <replaceable>integer</replaceable> records, records after the
+ limit will not be sorted. If omitted, the default value is
+ 1,000.
+ </para>
+ </listitem>
+ </varlistentry>
- </para>
+ <varlistentry>
+ <term>staticrank: <replaceable>integer</replaceable></term>
+ <listitem>
+ <para>
+ Enables whether static ranking is to be enabled (1) or
+ disabled (0). If omitted, it is disabled - corresponding
+ to a value of 0.
+ Refer to <xref linkend="administration-ranking-static"/> .
+ </para>
+ </listitem>
+ </varlistentry>
- <para>
- The port number defaults to 210 (standard Z39.50 port).
- </para>
- <para>
- Examples
- </para>
+ <varlistentry>
+ <term>estimatehits: <replaceable>integer</replaceable></term>
+ <listitem>
+ <para>
+ Controls whether &zebra; should calculate approximate hit counts and
+ at which hit count it is to be enabled.
+ A value of 0 disables approximate hit counts.
+ For a positive value approximate hit count is enabled
+ if it is known to be larger than <replaceable>integer</replaceable>.
+ </para>
+ <para>
+ Approximate hit counts can also be triggered by a particular
+ attribute in a query.
+ Refer to <xref linkend="querymodel-zebra-global-attr-limit"/>.
+ </para>
+ </listitem>
+ </varlistentry>
- <para>
+ <varlistentry>
+ <term>attset: <replaceable>filename</replaceable></term>
+ <listitem>
+ <para>
+ Specifies the filename(s) of attribute set files for use in
+ searching. In many configurations <filename>bib1.att</filename>
+ is used, but that is not required. If Classic Explain
+ attributes is to be used for searching,
+ <filename>explain.att</filename> must be given.
+ The path to att-files in general can be given using
+ <literal>profilePath</literal> setting.
+ See also <xref linkend="attset-files"/>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>memMax: <replaceable>size</replaceable></term>
+ <listitem>
+ <para>
+ Specifies <replaceable>size</replaceable> of internal memory
+ to use for the zebraidx program.
+ The amount is given in megabytes - default is 4 (4 MB).
+ The more memory, the faster large updates happen, up to about
+ half the free memory available on the computer.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>tempfiles: <replaceable>Yes/Auto/No</replaceable></term>
+ <listitem>
+ <para>
+ Tells zebra if it should use temporary files when indexing. The
+ default is Auto, in which case zebra uses temporary files only
+ if it would need more that <replaceable>memMax</replaceable>
+ megabytes of memory. This should be good for most uses.
+ </para>
+ </listitem>
+ </varlistentry>
- <screen>
- tcp:dranet.dra.com
+ <varlistentry>
+ <term>root: <replaceable>dir</replaceable></term>
+ <listitem>
+ <para>
+ Specifies a directory base for &zebra;. All relative paths
+ given (in profilePath, register, shadow) are based on this
+ directory. This setting is useful if your &zebra; server
+ is running in a different directory from where
+ <literal>zebra.cfg</literal> is located.
+ </para>
+ </listitem>
+ </varlistentry>
- ssl:secure.lib.com:3000
- </screen>
+ <varlistentry>
+ <term>passwd: <replaceable>file</replaceable></term>
+ <listitem>
+ <para>
+ Specifies a file with description of user accounts for &zebra;.
+ The format is similar to that known to Apache's htpasswd files
+ and UNIX' passwd files. Non-empty lines not beginning with
+ # are considered account lines. There is one account per-line.
+ A line consists of fields separate by a single colon character.
+ First field is username, second is password.
+ </para>
+ </listitem>
+ </varlistentry>
- </para>
+ <varlistentry>
+ <term>passwd.c: <replaceable>file</replaceable></term>
+ <listitem>
+ <para>
+ Specifies a file with description of user accounts for &zebra;.
+ File format is similar to that used by the passwd directive except
+ that the password are encrypted. Use Apache's htpasswd or similar
+ for maintenance.
+ </para>
+ </listitem>
+ </varlistentry>
- <para>
- In both cases, the special hostname "@" is mapped to
- the address INADDR_ANY, which causes the server to listen on any local
- interface. To start the server listening on the registered port for
- Z39.50, and to drop root privileges once the ports are bound, execute
- the server like this (from a root shell):
- </para>
+ <varlistentry>
+ <term>perm.<replaceable>user</replaceable>:
+ <replaceable>permstring</replaceable></term>
+ <listitem>
+ <para>
+ Specifies permissions (privilege) for a user that are allowed
+ to access &zebra; via the passwd system. There are two kinds
+ of permissions currently: read (r) and write(w). By default
+ users not listed in a permission directive are given the read
+ privilege. To specify permissions for a user with no
+ username, or &acro.z3950; anonymous style use
+ <literal>anonymous</literal>. The permstring consists of
+ a sequence of characters. Include character <literal>w</literal>
+ for write/update access, <literal>r</literal> for read access and
+ <literal>a</literal> to allow anonymous access through this account.
+ </para>
+ </listitem>
+ </varlistentry>
- <para>
+ <varlistentry>
+ <term>dbaccess: <replaceable>accessfile</replaceable></term>
+ <listitem>
+ <para>
+ Names a file which lists database subscriptions for individual users.
+ The access file should consists of lines of the form
+ <literal>username: dbnames</literal>, where dbnames is a list of
+ database names, separated by '+'. No whitespace is allowed in the
+ database list.
+ </para>
+ </listitem>
+ </varlistentry>
- <screen>
- zebrasrv -u daemon tcp:@
- </screen>
+ <varlistentry>
+ <term>encoding: <replaceable>charsetname</replaceable></term>
+ <listitem>
+ <para>
+ Tells &zebra; to interpret the terms in Z39.50 queries as
+ having been encoded using the specified character
+ encoding. The default is <literal>ISO-8859-1</literal>; one
+ useful alternative is <literal>UTF-8</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
- </para>
+ <varlistentry>
+ <term>storeKeys: <replaceable>value</replaceable></term>
+ <listitem>
+ <para>
+ Specifies whether &zebra; keeps a copy of indexed keys.
+ Use a value of 1 to enable; 0 to disable. If storeKeys setting is
+ omitted, it is enabled. Enabled storeKeys
+ are required for updating and deleting records. Disable only
+ storeKeys to save space and only plan to index data once.
+ </para>
+ </listitem>
+ </varlistentry>
- <para>
- You can replace <literal>daemon</literal> with another user, eg.
- your own account, or a dedicated IR server account.
- </para>
+ <varlistentry>
+ <term>storeData: <replaceable>value</replaceable></term>
+ <listitem>
+ <para>
+ Specifies whether &zebra; keeps a copy of indexed records.
+ Use a value of 1 to enable; 0 to disable. If storeData setting is
+ omitted, it is enabled. A storeData setting of 0 (disabled) makes
+ Zebra fetch records from the original locaction in the file
+ system using filename, file offset and file length. For the
+ DOM and ALVIS filter, the storeData setting is ignored.
+ </para>
+ </listitem>
+ </varlistentry>
- <para>
- The default behavior for <literal>zebrasrv</literal> is to establish
- a single TCP/IP listener, for the Z39.50 protocol, on port 9999.
- </para>
+ </variablelist>
+ </para>
- </sect1>
+ </sect1>
- <sect1 id="protocol-support">
- <title>Z39.50 Protocol Support and Behavior</title>
+ <sect1 id="locating-records">
+ <title>Locating Records</title>
- <sect2>
- <title>Initialization</title>
+ <para>
+ The default behavior of the &zebra; system is to reference the
+ records from their original location, i.e. where they were found when you
+ run <literal>zebraidx</literal>.
+ That is, when a client wishes to retrieve a record
+ following a search operation, the files are accessed from the place
+ where you originally put them - if you remove the files (without
+ running <literal>zebraidx</literal> again, the server will return
+ diagnostic number 14 (``System error in presenting records'') to
+ the client.
+ </para>
<para>
- During initialization, the server will negotiate to version 3 of the
- Z39.50 protocol, and the option bits for Search, Present, Scan,
- NamedResultSets, and concurrentOperations will be set, if requested by
- the client. The maximum PDU size is negotiated down to a maximum of
- 1Mb by default.
+ If your input files are not permanent - for example if you retrieve
+ your records from an outside source, or if they were temporarily
+ mounted on a CD-ROM drive,
+ you may want &zebra; to make an internal copy of them. To do this,
+ you specify 1 (true) in the <literal>storeData</literal> setting. When
+ the &acro.z3950; server retrieves the records they will be read from the
+ internal file structures of the system.
</para>
- </sect2>
+ </sect1>
- <sect2 id="search">
- <title>Search</title>
+ <sect1 id="simple-indexing">
+ <title>Indexing with no Record IDs (Simple Indexing)</title>
<para>
- The supported query type are 1 and 101. All operators are currently
- supported with the restriction that only proximity units of type "word"
- are supported for the proximity operator.
- Queries can be arbitrarily complex.
- Named result sets are supported, and result sets can be used as operands
- without limitations.
- Searches may span multiple databases.
+ If you have a set of records that are not expected to change over time
+ you may can build your database without record IDs.
+ This indexing method uses less space than the other methods and
+ is simple to use.
</para>
<para>
- The server has full support for piggy-backed present requests (see
- also the following section).
+ To use this method, you simply omit the <literal>recordId</literal> entry
+ for the group of files that you index. To add a set of records you use
+ <literal>zebraidx</literal> with the <literal>update</literal> command. The
+ <literal>update</literal> command will always add all of the records that it
+ encounters to the index - whether they have already been indexed or
+ not. If the set of indexed files change, you should delete all of the
+ index files, and build a new index from scratch.
</para>
<para>
- <emphasis>Use</emphasis> attributes are interpreted according to the
- attribute sets which have been loaded in the
- <literal>zebra.cfg</literal> file, and are matched against specific
- fields as specified in the <literal>.abs</literal> file which
- describes the profile of the records which have been loaded.
- If no Use attribute is provided, a default of Bib-1 Any is assumed.
+ Consider a system in which you have a group of text files called
+ <literal>simple</literal>.
+ That group of records should belong to a &acro.z3950; database called
+ <literal>textbase</literal>.
+ The following <literal>zebra.cfg</literal> file will suffice:
</para>
-
<para>
- If a <emphasis>Structure</emphasis> attribute of
- <emphasis>Phrase</emphasis> is used in conjunction with a
- <emphasis>Completeness</emphasis> attribute of
- <emphasis>Complete (Sub)field</emphasis>, the term is matched
- against the contents of the phrase (long word) register, if one
- exists for the given <emphasis>Use</emphasis> attribute.
- A phrase register is created for those fields in the
- <literal>.abs</literal> file that contains a
- <literal>p</literal>-specifier.
- </para>
- <para>
- If <emphasis>Structure</emphasis>=<emphasis>Phrase</emphasis> is
- used in conjunction with <emphasis>Incomplete Field</emphasis> - the
- default value for <emphasis>Completeness</emphasis>, the
- search is directed against the normal word registers, but if the term
- contains multiple words, the term will only match if all of the words
- are found immediately adjacent, and in the given order.
- The word search is performed on those fields that are indexed as
- type <literal>w</literal> in the <literal>.abs</literal> file.
+ <screen>
+ profilePath: /usr/local/idzebra/tab
+ attset: bib1.att
+ simple.recordType: text
+ simple.database: textbase
+ </screen>
+
</para>
<para>
- If the <emphasis>Structure</emphasis> attribute is
- <emphasis>Word List</emphasis>,
- <emphasis>Free-form Text</emphasis>, or
- <emphasis>Document Text</emphasis>, the term is treated as a
- natural-language, relevance-ranked query.
- This search type uses the word register, i.e. those fields
- that are indexed as type <literal>w</literal> in the
- <literal>.abs</literal> file.
+ Since the existing records in an index can not be addressed by their
+ IDs, it is impossible to delete or modify records when using this method.
</para>
+ </sect1>
+
+ <sect1 id="file-ids">
+ <title>Indexing with File Record IDs</title>
+
<para>
- If the <emphasis>Structure</emphasis> attribute is
- <emphasis>Numeric String</emphasis> the term is treated as an integer.
- The search is performed on those fields that are indexed
- as type <literal>n</literal> in the <literal>.abs</literal> file.
+ If you have a set of files that regularly change over time: Old files
+ are deleted, new ones are added, or existing files are modified, you
+ can benefit from using the <emphasis>file ID</emphasis>
+ indexing methodology.
+ Examples of this type of database might include an index of WWW
+ resources, or a USENET news spool area.
+ Briefly speaking, the file key methodology uses the directory paths
+ of the individual records as a unique identifier for each record.
+ To perform indexing of a directory with file keys, again, you specify
+ the top-level directory after the <literal>update</literal> command.
+ The command will recursively traverse the directories and compare
+ each one with whatever have been indexed before in that same directory.
+ If a file is new (not in the previous version of the directory) it
+ is inserted into the registers; if a file was already indexed and
+ it has been modified since the last update, the index is also
+ modified; if a file has been removed since the last
+ visit, it is deleted from the index.
</para>
<para>
- If the <emphasis>Structure</emphasis> attribute is
- <emphasis>URx</emphasis> the term is treated as a URX (URL) entity.
- The search is performed on those fields that are indexed as type
- <literal>u</literal> in the <literal>.abs</literal> file.
+ The resulting system is easy to administrate. To delete a record you
+ simply have to delete the corresponding file (say, with the
+ <literal>rm</literal> command). And to add records you create new
+ files (or directories with files). For your changes to take effect
+ in the register you must run <literal>zebraidx update</literal> with
+ the same directory root again. This mode of operation requires more
+ disk space than simpler indexing methods, but it makes it easier for
+ you to keep the index in sync with a frequently changing set of data.
+ If you combine this system with the <emphasis>safe update</emphasis>
+ facility (see below), you never have to take your server off-line for
+ maintenance or register updating purposes.
</para>
<para>
- If the <emphasis>Structure</emphasis> attribute is
- <emphasis>Local Number</emphasis> the term is treated as
- native Zebra Record Identifier.
+ To enable indexing with pathname IDs, you must specify
+ <literal>file</literal> as the value of <literal>recordId</literal>
+ in the configuration file. In addition, you should set
+ <literal>storeKeys</literal> to <literal>1</literal>, since the &zebra;
+ indexer must save additional information about the contents of each record
+ in order to modify the indexes correctly at a later time.
</para>
+ <!--
+ FIXME - There must be a simpler way to do this with Adams string tags -H
+ -->
+
<para>
- If the <emphasis>Relation</emphasis> attribute is
- <emphasis>Equals</emphasis> (default), the term is matched
- in a normal fashion (modulo truncation and processing of
- individual words, if required).
- If <emphasis>Relation</emphasis> is <emphasis>Less Than</emphasis>,
- <emphasis>Less Than or Equal</emphasis>,
- <emphasis>Greater than</emphasis>, or <emphasis>Greater than or
- Equal</emphasis>, the term is assumed to be numerical, and a
- standard regular expression is constructed to match the given
- expression.
- If <emphasis>Relation</emphasis> is <emphasis>Relevance</emphasis>,
- the standard natural-language query processor is invoked.
+ For example, to update records of group <literal>esdd</literal>
+ located below
+ <literal>/data1/records/</literal> you should type:
+ <screen>
+ $ zebraidx -g esdd update /data1/records
+ </screen>
</para>
<para>
- For the <emphasis>Truncation</emphasis> attribute,
- <emphasis>No Truncation</emphasis> is the default.
- <emphasis>Left Truncation</emphasis> is not supported.
- <emphasis>Process #</emphasis> is supported, as is
- <emphasis>Regxp-1</emphasis>.
- <emphasis>Regxp-2</emphasis> enables the fault-tolerant (fuzzy)
- search. As a default, a single error (deletion, insertion,
- replacement) is accepted when terms are matched against the register
- contents.
+ The corresponding configuration file includes:
+ <screen>
+ esdd.recordId: file
+ esdd.recordType: grs.sgml
+ esdd.storeKeys: 1
+ </screen>
</para>
- <sect3>
- <title>Regular expressions</title>
-
- <para>
- Each term in a query is interpreted as a regular expression if
- the truncation value is either <emphasis>Regxp-1</emphasis> (102)
- or <emphasis>Regxp-2</emphasis> (103).
- Both query types follow the same syntax with the operands:
- <variablelist>
-
- <varlistentry>
- <term>x</term>
- <listitem>
- <para>
- Matches the character <emphasis>x</emphasis>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>.</term>
- <listitem>
- <para>
- Matches any character.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>[</literal>..<literal>]</literal></term>
- <listitem>
- <para>
- Matches the set of characters specified;
- such as <literal>[abc]</literal> or <literal>[a-c]</literal>.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- and the operators:
- <variablelist>
-
- <varlistentry>
- <term>x*</term>
- <listitem>
- <para>
- Matches <emphasis>x</emphasis> zero or more times. Priority: high.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>x+</term>
- <listitem>
- <para>
- Matches <emphasis>x</emphasis> one or more times. Priority: high.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>x?</term>
- <listitem>
- <para>
- Matches <emphasis>x</emphasis> once or twice. Priority: high.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>xy</term>
- <listitem>
- <para>
- Matches <emphasis>x</emphasis>, then <emphasis>y</emphasis>.
- Priority: medium.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>x|y</term>
- <listitem>
- <para>
- Matches either <emphasis>x</emphasis> or <emphasis>y</emphasis>.
- Priority: low.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- The order of evaluation may be changed by using parentheses.
- </para>
-
- <para>
- If the first character of the <emphasis>Regxp-2</emphasis> query
- is a plus character (<literal>+</literal>) it marks the
- beginning of a section with non-standard specifiers.
- The next plus character marks the end of the section.
- Currently Zebra only supports one specifier, the error tolerance,
- which consists one digit.
+ <note>
+ <para>You cannot start out with a group of records with simple
+ indexing (no record IDs as in the previous section) and then later
+ enable file record Ids. &zebra; must know from the first time that you
+ index the group that
+ the files should be indexed with file record IDs.
</para>
+ </note>
- <para>
- Since the plus operator is normally a suffix operator the addition to
- the query syntax doesn't violate the syntax for standard regular
- expressions.
- </para>
+ <para>
+ You cannot explicitly delete records when using this method (using the
+ <literal>delete</literal> command to <literal>zebraidx</literal>. Instead
+ you have to delete the files from the file system (or move them to a
+ different location)
+ and then run <literal>zebraidx</literal> with the
+ <literal>update</literal> command.
+ </para>
+ <!-- ### what happens if a file contains multiple records? -->
+ </sect1>
- </sect3>
+ <sect1 id="generic-ids">
+ <title>Indexing with General Record IDs</title>
- <sect3>
- <title>Query examples</title>
+ <para>
+ When using this method you construct an (almost) arbitrary, internal
+ record key based on the contents of the record itself and other system
+ information. If you have a group of records that explicitly associates
+ an ID with each record, this method is convenient. For example, the
+ record format may contain a title or a ID-number - unique within the group.
+ In either case you specify the &acro.z3950; attribute set and use-attribute
+ location in which this information is stored, and the system looks at
+ that field to determine the identity of the record.
+ </para>
- <para>
- Phrase search for <emphasis>information retrieval</emphasis> in
- the title-register:
- <screen>
- @attr 1=4 "information retrieval"
- </screen>
- </para>
+ <para>
+ As before, the record ID is defined by the <literal>recordId</literal>
+ setting in the configuration file. The value of the record ID specification
+ consists of one or more tokens separated by whitespace. The resulting
+ ID is represented in the index by concatenating the tokens and
+ separating them by ASCII value (1).
+ </para>
- <para>
- Ranked search for the same thing:
- <screen>
- @attr 1=4 @attr 2=102 "Information retrieval"
- </screen>
- </para>
+ <para>
+ There are three kinds of tokens:
+ <variablelist>
- <para>
- Phrase search with a regular expression:
- <screen>
- @attr 1=4 @attr 5=102 "informat.* retrieval"
- </screen>
- </para>
+ <varlistentry>
+ <term>Internal record info</term>
+ <listitem>
+ <para>
+ The token refers to a key that is
+ extracted from the record. The syntax of this token is
+ <literal>(</literal> <emphasis>set</emphasis> <literal>,</literal>
+ <emphasis>use</emphasis> <literal>)</literal>,
+ where <emphasis>set</emphasis> is the
+ attribute set name <emphasis>use</emphasis> is the
+ name or value of the attribute.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>System variable</term>
+ <listitem>
+ <para>
+ The system variables are preceded by
+
+ <screen>
+ $
+ </screen>
+ and immediately followed by the system variable name, which
+ may one of
+ <variablelist>
+
+ <varlistentry>
+ <term>group</term>
+ <listitem>
+ <para>
+ Group name.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>database</term>
+ <listitem>
+ <para>
+ Current database specified.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>type</term>
+ <listitem>
+ <para>
+ Record type.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Constant string</term>
+ <listitem>
+ <para>
+ A string used as part of the ID — surrounded
+ by single- or double quotes.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
- <para>
- Ranked search with a regular expression:
- <screen>
- @attr 1=4 @attr 5=102 @attr 2=102 "informat.* retrieval"
- </screen>
- </para>
+ <para>
+ For instance, the sample GILS records that come with the &zebra;
+ distribution contain a unique ID in the data tagged Control-Identifier.
+ The data is mapped to the &acro.bib1; use attribute Identifier-standard
+ (code 1007). To use this field as a record id, specify
+ <literal>(bib1,Identifier-standard)</literal> as the value of the
+ <literal>recordId</literal> in the configuration file.
+ If you have other record types that uses the same field for a
+ different purpose, you might add the record type
+ (or group or database name) to the record id of the gils
+ records as well, to prevent matches with other types of records.
+ In this case the recordId might be set like this:
- <para>
- In the GILS schema (<literal>gils.abs</literal>), the
- west-bounding-coordinate is indexed as type <literal>n</literal>,
- and is therefore searched by specifying
- <emphasis>structure</emphasis>=<emphasis>Numeric String</emphasis>.
- To match all those records with west-bounding-coordinate greater
- than -114 we use the following query:
- <screen>
- @attr 4=109 @attr 2=5 @attr gils 1=2038 -114
- </screen>
- </para>
- </sect3>
- </sect2>
+ <screen>
+ gils.recordId: $type (bib1,Identifier-standard)
+ </screen>
- <sect2>
- <title>Present</title>
- <para>
- The present facility is supported in a standard fashion. The requested
- record syntax is matched against the ones supported by the profile of
- each record retrieved. If no record syntax is given, SUTRS is the
- default. The requested element set name, again, is matched against any
- provided by the relevant record profiles.
- </para>
- </sect2>
- <sect2>
- <title>Scan</title>
- <para>
- The attribute combinations provided with the termListAndStartPoint are
- processed in the same way as operands in a query (see above).
- Currently, only the term and the globalOccurrences are returned with
- the termInfo structure.
</para>
- </sect2>
- <sect2>
- <title>Sort</title>
<para>
- Z39.50 specifies three diffent types of sort criterias.
- Of these Zebra supports the attribute specification type in which
- case the use attribute specifies the "Sort register".
- Sort registers are created for those fields that are of type "sort" in
- the default.idx file.
- The corresponding character mapping file in default.idx specifies the
- ordinal of each character used in the actual sort.
+ (see <xref linkend="grs"/>
+ for details of how the mapping between elements of your records and
+ searchable attributes is established).
</para>
<para>
- Z39.50 allows the client to specify sorting on one or more input
- result sets and one output result set.
- Zebra supports sorting on one result set only which may or may not
- be the same as the output result set.
+ As for the file record ID case described in the previous section,
+ updating your system is simply a matter of running
+ <literal>zebraidx</literal>
+ with the <literal>update</literal> command. However, the update with general
+ keys is considerably slower than with file record IDs, since all files
+ visited must be (re)read to discover their IDs.
</para>
- </sect2>
- <sect2>
- <title>Close</title>
+
<para>
- If a Close PDU is received, the server will respond with a Close PDU
- with reason=FINISHED, no matter which protocol version was negotiated
- during initialization. If the protocol version is 3 or more, the
- server will generate a Close PDU under certain circumstances,
- including a session timeout (60 minutes by default), and certain kinds of
- protocol errors. Once a Close PDU has been sent, the protocol
- association is considered broken, and the transport connection will be
- closed immediately upon receipt of further data, or following a short
- timeout.
+ As you might expect, when using the general record IDs
+ method, you can only add or modify existing records with the
+ <literal>update</literal> command.
+ If you wish to delete records, you must use the,
+ <literal>delete</literal> command, with a directory as a parameter.
+ This will remove all records that match the files below that root
+ directory.
</para>
- </sect2>
- </sect1>
-</chapter>
-
-<chapter id="record-model">
- <title>The Record Model</title>
-
- <para>
- The Zebra system is designed to support a wide range of data management
- applications. The system can be configured to handle virtually any
- kind of structured data. Each record in the system is associated with
- a <emphasis>record schema</emphasis> which lends context to the data
- elements of the record.
- Any number of record schema can coexist in the system.
- Although it may be wise to use only a single schema within
- one database, the system poses no such restrictions.
- </para>
-
- <para>
- The record model described in this chapter applies to the fundamental,
- structured
- record type <literal>grs</literal> as introduced in
- section <xref linkend="record-types"/>.
- </para>
-
- <para>
- Records pass through three different states during processing in the
- system.
- </para>
-
- <para>
-
- <itemizedlist>
- <listitem>
-
- <para>
- When records are accessed by the system, they are represented
- in their local, or native format. This might be SGML or HTML files,
- News or Mail archives, MARC records. If the system doesn't already
- know how to read the type of data you need to store, you can set up an
- input filter by preparing conversion rules based on regular
- expressions and possibly augmented by a flexible scripting language
- (Tcl).
- The input filter produces as output an internal representation:
-
- </para>
- </listitem>
- <listitem>
-
- <para>
- When records are processed by the system, they are represented
- in a tree-structure, constructed by tagged data elements hanging off a
- root node. The tagged elements may contain data or yet more tagged
- elements in a recursive structure. The system performs various
- actions on this tree structure (indexing, element selection, schema
- mapping, etc.),
-
- </para>
- </listitem>
- <listitem>
-
- <para>
- Before transmitting records to the client, they are first
- converted from the internal structure to a form suitable for exchange
- over the network - according to the Z39.50 standard.
- </para>
- </listitem>
-
- </itemizedlist>
-
- </para>
-
- <sect1 id="local-representation">
- <title>Local Representation</title>
-
- <para>
- As mentioned earlier, Zebra places few restrictions on the type of
- data that you can index and manage. Generally, whatever the form of
- the data, it is parsed by an input filter specific to that format, and
- turned into an internal structure that Zebra knows how to handle. This
- process takes place whenever the record is accessed - for indexing and
- retrieval.
- </para>
-
- <para>
- The RecordType parameter in the <literal>zebra.cfg</literal> file, or
- the <literal>-t</literal> option to the indexer tells Zebra how to
- process input records.
- Two basic types of processing are available - raw text and structured
- data. Raw text is just that, and it is selected by providing the
- argument <emphasis>text</emphasis> to Zebra. Structured records are
- all handled internally using the basic mechanisms described in the
- subsequent sections.
- Zebra can read structured records in many different formats.
- How this is done is governed by additional parameters after the
- "grs" keyboard, separated by "." characters.
- </para>
-
- <para>
- Three basic subtypes to the <emphasis>grs</emphasis> type are
- currently available:
- </para>
- <para>
- <variablelist>
- <varlistentry>
- <term>grs.sgml</term>
- <listitem>
- <para>
- This is the canonical input format —
- described below. It is a simple SGML-like syntax.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>grs.regx.<emphasis>filter</emphasis></term>
- <listitem>
- <para>
- This enables a user-supplied input
- filter. The mechanisms of these filters are described below.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>grs.marc.<emphasis>abstract syntax</emphasis></term>
- <listitem>
- <para>
- This allows Zebra to read
- records in the ISO2709 (MARC) encoding standard. In this case, the
- last paramemeter <emphasis>abstract syntax</emphasis> names the
- <literal>.abs</literal> file (see below)
- which describes the specific MARC structure of the input record as
- well as the indexing rules.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
+ </sect1>
- <sect2>
- <title>Canonical Input Format</title>
+ <sect1 id="register-location">
+ <title>Register Location</title>
<para>
- Although input data can take any form, it is sometimes useful to
- describe the record processing capabilities of the system in terms of
- a single, canonical input format that gives access to the full
- spectrum of structure and flexibility in the system. In Zebra, this
- canonical format is an "SGML-like" syntax.
+ Normally, the index files that form dictionaries, inverted
+ files, record info, etc., are stored in the directory where you run
+ <literal>zebraidx</literal>. If you wish to store these, possibly large,
+ files somewhere else, you must add the <literal>register</literal>
+ entry to the <literal>zebra.cfg</literal> file.
+ Furthermore, the &zebra; system allows its file
+ structures to span multiple file systems, which is useful for
+ managing very large databases.
</para>
<para>
- To use the canonical format specify <literal>grs.sgml</literal> as
- the record type.
- </para>
+ The value of the <literal>register</literal> setting is a sequence
+ of tokens. Each token takes the form:
- <para>
- Consider a record describing an information resource (such a record is
- sometimes known as a <emphasis>locator record</emphasis>).
- It might contain a field describing the distributor of the
- information resource, which might in turn be partitioned into
- various fields providing details about the distributor, like this:
+ <emphasis>dir</emphasis><literal>:</literal><emphasis>size</emphasis>
+
+ The <emphasis>dir</emphasis> specifies a directory in which index files
+ will be stored and the <emphasis>size</emphasis> specifies the maximum
+ size of all files in that directory. The &zebra; indexer system fills
+ each directory in the order specified and use the next specified
+ directories as needed.
+ The <emphasis>size</emphasis> is an integer followed by a qualifier
+ code,
+ <literal>b</literal> for bytes,
+ <literal>k</literal> for kilobytes.
+ <literal>M</literal> for megabytes,
+ <literal>G</literal> for gigabytes.
+ Specifying a negative value disables the checking (it still needs the unit,
+ use <literal>-1b</literal>).
</para>
<para>
+ For instance, if you have allocated three disks for your register, and
+ the first disk is mounted
+ on <literal>/d1</literal> and has 2GB of free space, the
+ second, mounted on <literal>/d2</literal> has 3.6 GB, and the third,
+ on which you have more space than you bother to worry about, mounted on
+ <literal>/d3</literal> you could put this entry in your configuration file:
<screen>
- <Distributor>
- <Name> USGS/WRD </Name>
- <Organization> USGS/WRD </Organization>
- <Street-Address>
- U.S. GEOLOGICAL SURVEY, 505 MARQUETTE, NW
- </Street-Address>
- <City> ALBUQUERQUE </City>
- <State> NM </State>
- <Zip-Code> 87102 </Zip-Code>
- <Country> USA </Country>
- <Telephone> (505) 766-5560 </Telephone>
- </Distributor>
+ register: /d1:2G /d2:3600M /d3:-1b
</screen>
-
</para>
- <note>
<para>
- The indentation used above is used to illustrate how Zebra
- interprets the markup. The indentation, in itself, has no
- significance to the parser for the canonical input format, which
- discards superfluous whitespace.
- </para>
- </note>
- <para>
- The keywords surrounded by <...> are
- <emphasis>tags</emphasis>, while the sections of text
- in between are the <emphasis>data elements</emphasis>.
- A data element is characterized by its location in the tree
- that is made up by the nested elements.
- Each element is terminated by a closing tag - beginning
- with <literal><</literal>/, and containing the same symbolic
- tag-name as the corresponding opening tag.
- The general closing tag - <literal><</literal>>/ -
- terminates the element started by the last opening tag. The
- structuring of elements is significant.
- The element <emphasis>Telephone</emphasis>,
- for instance, may be indexed and presented to the client differently,
- depending on whether it appears inside the
- <emphasis>Distributor</emphasis> element, or some other,
- structured data element such a <emphasis>Supplier</emphasis> element.
+ Note that &zebra; does not verify that the amount of space specified is
+ actually available on the directory (file system) specified - it is
+ your responsibility to ensure that enough space is available, and that
+ other applications do not attempt to use the free space. In a large
+ production system, it is recommended that you allocate one or more
+ file system exclusively to the &zebra; register files.
</para>
- <sect3>
- <title>Record Root</title>
+ </sect1>
+
+ <sect1 id="shadow-registers">
+ <title>Safe Updating - Using Shadow Registers</title>
+
+ <sect2 id="shadow-registers-description">
+ <title>Description</title>
<para>
- The first tag in a record describes the root node of the tree that
- makes up the total record. In the canonical input format, the root tag
- should contain the name of the schema that lends context to the
- elements of the record (see section
- <xref linkend="internal-representation"/>).
- The following is a GILS record that
- contains only a single element (strictly speaking, that makes it an
- illegal GILS record, since the GILS profile includes several mandatory
- elements - Zebra does not validate the contents of a record against
- the Z39.50 profile, however - it merely attempts to match up elements
- of a local representation with the given schema):
+ The &zebra; server supports <emphasis>updating</emphasis> of the index
+ structures. That is, you can add, modify, or remove records from
+ databases managed by &zebra; without rebuilding the entire index.
+ Since this process involves modifying structured files with various
+ references between blocks of data in the files, the update process
+ is inherently sensitive to system crashes, or to process interruptions:
+ Anything but a successfully completed update process will leave the
+ register files in an unknown state, and you will essentially have no
+ recourse but to re-index everything, or to restore the register files
+ from a backup medium.
+ Further, while the update process is active, users cannot be
+ allowed to access the system, as the contents of the register files
+ may change unpredictably.
</para>
<para>
+ You can solve these problems by enabling the shadow register system in
+ &zebra;.
+ During the updating procedure, <literal>zebraidx</literal> will temporarily
+ write changes to the involved files in a set of "shadow
+ files", without modifying the files that are accessed by the
+ active server processes. If the update procedure is interrupted by a
+ system crash or a signal, you simply repeat the procedure - the
+ register files have not been changed or damaged, and the partially
+ written shadow files are automatically deleted before the new updating
+ procedure commences.
+ </para>
- <screen>
- <gils>
- <title>Zen and the Art of Motorcycle Maintenance</title>
- </gils>
- </screen>
-
+ <para>
+ At the end of the updating procedure (or in a separate operation, if
+ you so desire), the system enters a "commit mode". First,
+ any active server processes are forced to access those blocks that
+ have been changed from the shadow files rather than from the main
+ register files; the unmodified blocks are still accessed at their
+ normal location (the shadow files are not a complete copy of the
+ register files - they only contain those parts that have actually been
+ modified). If the commit process is interrupted at any point during the
+ commit process, the server processes will continue to access the
+ shadow files until you can repeat the commit procedure and complete
+ the writing of data to the main register files. You can perform
+ multiple update operations to the registers before you commit the
+ changes to the system files, or you can execute the commit operation
+ at the end of each update operation. When the commit phase has
+ completed successfully, any running server processes are instructed to
+ switch their operations to the new, operational register, and the
+ temporary shadow files are deleted.
</para>
- </sect3>
+ </sect2>
- <sect3>
- <title>Variants</title>
+ <sect2 id="shadow-registers-how-to-use">
+ <title>How to Use Shadow Register Files</title>
<para>
- Zebra allows you to provide individual data elements in a number of
- <emphasis>variant forms</emphasis>. Examples of variant forms are
- textual data elements which might appear in different languages, and
- images which may appear in different formats or layouts.
- The variant system in Zebra is essentially a representation of
- the variant mechanism of Z39.50-1995.
+ The first step is to allocate space on your system for the shadow
+ files.
+ You do this by adding a <literal>shadow</literal> entry to the
+ <literal>zebra.cfg</literal> file.
+ The syntax of the <literal>shadow</literal> entry is exactly the
+ same as for the <literal>register</literal> entry
+ (see <xref linkend="register-location"/>).
+ The location of the shadow area should be
+ <emphasis>different</emphasis> from the location of the main register
+ area (if you have specified one - remember that if you provide no
+ <literal>register</literal> setting, the default register area is the
+ working directory of the server and indexing processes).
</para>
<para>
- The following is an example of a title element which occurs in two
- different languages.
+ The following excerpt from a <literal>zebra.cfg</literal> file shows
+ one example of a setup that configures both the main register
+ location and the shadow file area.
+ Note that two directories or partitions have been set aside
+ for the shadow file area. You can specify any number of directories
+ for each of the file areas, but remember that there should be no
+ overlaps between the directories used for the main registers and the
+ shadow files, respectively.
</para>
-
<para>
<screen>
- <title>
- <var lang lang "eng">
- Zen and the Art of Motorcycle Maintenance</>
- <var lang lang "dan">
- Zen og Kunsten at Vedligeholde en Motorcykel</>
- </title>
+ register: /d1:500M
+ shadow: /scratch1:100M /scratch2:200M
</screen>
</para>
<para>
- The syntax of the <emphasis>variant element</emphasis> is
- <literal><var class type value></literal>.
- The available values for the <emphasis>class</emphasis> and
- <emphasis>type</emphasis> fields are given by the variant set
- that is associated with the current schema
- (see section <xref linkend="variant-set"/>).
- </para>
-
- <para>
- Variant elements are terminated by the general end-tag </>, by
- the variant end-tag </var>, by the appearance of another variant
- tag with the same <emphasis>class</emphasis> and
- <emphasis>value</emphasis> settings, or by the
- appearance of another, normal tag. In other words, the end-tags for
- the variants used in the example above could have been saved.
- </para>
-
- <para>
- Variant elements can be nested. The element
+ When shadow files are enabled, an extra command is available at the
+ <literal>zebraidx</literal> command line.
+ In order to make changes to the system take effect for the
+ users, you'll have to submit a "commit" command after a
+ (sequence of) update operation(s).
</para>
<para>
<screen>
- <title>
- <var lang lang "eng"><var body iana "text/plain">
- Zen and the Art of Motorcycle Maintenance
- </title>
+ $ zebraidx update /d1/records
+ $ zebraidx commit
</screen>
</para>
<para>
- Associates two variant components to the variant list for the title
- element.
- </para>
-
- <para>
- Given the nesting rules described above, we could write
+ Or you can execute multiple updates before committing the changes:
</para>
<para>
<screen>
- <title>
- <var body iana "text/plain>
- <var lang lang "eng">
- Zen and the Art of Motorcycle Maintenance
- <var lang lang "dan">
- Zen og Kunsten at Vedligeholde en Motorcykel
- </title>
+ $ zebraidx -g books update /d1/records /d2/more-records
+ $ zebraidx -g fun update /d3/fun-records
+ $ zebraidx commit
</screen>
</para>
<para>
- The title element above comes in two variants. Both have the IANA body
- type "text/plain", but one is in English, and the other in
- Danish. The client, using the element selection mechanism of Z39.50,
- can retrieve information about the available variant forms of data
- elements, or it can select specific variants based on the requirements
- of the end-user.
+ If one of the update operations above had been interrupted, the commit
+ operation on the last line would fail: <literal>zebraidx</literal>
+ will not let you commit changes that would destroy the running register.
+ You'll have to rerun all of the update operations since your last
+ commit operation, before you can commit the new changes.
</para>
- </sect3>
+ <para>
+ Similarly, if the commit operation fails, <literal>zebraidx</literal>
+ will not let you start a new update operation before you have
+ successfully repeated the commit operation.
+ The server processes will keep accessing the shadow files rather
+ than the (possibly damaged) blocks of the main register files
+ until the commit operation has successfully completed.
+ </para>
- </sect2>
+ <para>
+ You should be aware that update operations may take slightly longer
+ when the shadow register system is enabled, since more file access
+ operations are involved. Further, while the disk space required for
+ the shadow register data is modest for a small update operation, you
+ may prefer to disable the system if you are adding a very large number
+ of records to an already very large database (we use the terms
+ <emphasis>large</emphasis> and <emphasis>modest</emphasis>
+ very loosely here, since every application will have a
+ different perception of size).
+ To update the system without the use of the the shadow files,
+ simply run <literal>zebraidx</literal> with the <literal>-n</literal>
+ option (note that you do not have to execute the
+ <emphasis>commit</emphasis> command of <literal>zebraidx</literal>
+ when you temporarily disable the use of the shadow registers in
+ this fashion.
+ Note also that, just as when the shadow registers are not enabled,
+ server processes will be barred from accessing the main register
+ while the update procedure takes place.
+ </para>
- <sect2>
- <title>Input Filters</title>
+ </sect2>
- <para>
- In order to handle general input formats, Zebra allows the
- operator to define filters which read individual records in their
- native format and produce an internal representation that the system
- can work with.
- </para>
+ </sect1>
- <para>
- Input filters are ASCII files, generally with the suffix
- <literal>.flt</literal>.
- The system looks for the files in the directories given in the
- <emphasis>profilePath</emphasis> setting in the
- <literal>zebra.cfg</literal> files.
- The record type for the filter is
- <literal>grs.regx.</literal><emphasis>filter-filename</emphasis>
- (fundamental type <literal>grs</literal>, file read
- type <literal>regx</literal>, argument
- <emphasis>filter-filename</emphasis>).
- </para>
-
- <para>
- Generally, an input filter consists of a sequence of rules, where each
- rule consists of a sequence of expressions, followed by an action. The
- expressions are evaluated against the contents of the input record,
- and the actions normally contribute to the generation of an internal
- representation of the record.
- </para>
-
- <para>
- An expression can be either of the following:
- </para>
- <para>
- <variablelist>
+ <sect1 id="administration-ranking">
+ <title>Relevance Ranking and Sorting of Result Sets</title>
- <varlistentry>
- <term>INIT</term>
- <listitem>
- <para>
- The action associated with this expression is evaluated
- exactly once in the lifetime of the application, before any records
- are read. It can be used in conjunction with an action that
- initializes tables or other resources that are used in the processing
- of input records.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>BEGIN</term>
- <listitem>
- <para>
- Matches the beginning of the record. It can be used to
- initialize variables, etc. Typically, the
- <emphasis>BEGIN</emphasis> rule is also used
- to establish the root node of the record.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>END</term>
- <listitem>
- <para>
- Matches the end of the record - when all of the contents
- of the record has been processed.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>/pattern/</term>
- <listitem>
- <para>
- Matches a string of characters from the input record.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>BODY</term>
- <listitem>
- <para>
- This keyword may only be used between two patterns.
- It matches everything between (not including) those patterns.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>FINISH</term>
- <listitem>
- <para>
- The expression asssociated with this pattern is evaluated
- once, before the application terminates. It can be used to release
- system resources - typically ones allocated in the
- <emphasis>INIT</emphasis> step.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
+ <sect2 id="administration-overview">
+ <title>Overview</title>
+ <para>
+ The default ordering of a result set is left up to the server,
+ which inside &zebra; means sorting in ascending document ID order.
+ This is not always the order humans want to browse the sometimes
+ quite large hit sets. Ranking and sorting comes to the rescue.
+ </para>
- <para>
- An action is surrounded by curly braces ({...}), and
- consists of a sequence of statements. Statements may be separated
- by newlines or semicolons (;).
- Within actions, the strings that matched the expressions
- immediately preceding the action can be referred to as
- $0, $1, $2, etc.
- </para>
+ <para>
+ In cases where a good presentation ordering can be computed at
+ indexing time, we can use a fixed <literal>static ranking</literal>
+ scheme, which is provided for the <literal>alvis</literal>
+ indexing filter. This defines a fixed ordering of hit lists,
+ independently of the query issued.
+ </para>
- <para>
- The available statements are:
- </para>
+ <para>
+ There are cases, however, where relevance of hit set documents is
+ highly dependent on the query processed.
+ Simply put, <literal>dynamic relevance ranking</literal>
+ sorts a set of retrieved records such that those most likely to be
+ relevant to your request are retrieved first.
+ Internally, &zebra; retrieves all documents that satisfy your
+ query, and re-orders the hit list to arrange them based on
+ a measurement of similarity between your query and the content of
+ each record.
+ </para>
- <para>
- <variablelist>
+ <para>
+ Finally, there are situations where hit sets of documents should be
+ <literal>sorted</literal> during query time according to the
+ lexicographical ordering of certain sort indexes created at
+ indexing time.
+ </para>
+ </sect2>
- <varlistentry>
- <term>begin <emphasis>type [parameter ... ]</emphasis></term>
- <listitem>
- <para>
- Begin a new
- data element. The type is one of the following:
- <variablelist>
-
- <varlistentry>
- <term>record</term>
- <listitem>
- <para>
- Begin a new record. The followingparameter should be the
- name of the schema that describes the structure of the record, eg.
- <literal>gils</literal> or <literal>wais</literal> (see below).
- The <literal>begin record</literal> call should precede
- any other use of the <emphasis>begin</emphasis> statement.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>element</term>
- <listitem>
- <para>
- Begin a new tagged element. The parameter is the
- name of the tag. If the tag is not matched anywhere in the tagsets
- referenced by the current schema, it is treated as a local string
- tag.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>variant</term>
- <listitem>
- <para>
- Begin a new node in a variant tree. The parameters are
- <emphasis>class type value</emphasis>.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>data</term>
- <listitem>
- <para>
- Create a data element. The concatenated arguments make
- up the value of the data element.
- The option <literal>-text</literal> signals that
- the layout (whitespace) of the data should be retained for
- transmission.
- The option <literal>-element</literal>
- <emphasis>tag</emphasis> wraps the data up in
- the <emphasis>tag</emphasis>.
- The use of the <literal>-element</literal> option is equivalent to
- preceding the command with a <emphasis>begin
- element</emphasis> command, and following
- it with the <emphasis>end</emphasis> command.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>end <emphasis>[type]</emphasis></term>
- <listitem>
- <para>
- Close a tagged element. If no parameter is given,
- the last element on the stack is terminated.
- The first parameter, if any, is a type name, similar
- to the <emphasis>begin</emphasis> statement.
- For the <emphasis>element</emphasis> type, a tag
- name can be provided to terminate a specific tag.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
- <para>
- The following input filter reads a Usenet news file, producing a
- record in the WAIS schema. Note that the body of a news posting is
- separated from the list of headers by a blank line (or rather a
- sequence of two newline characters.
- </para>
+ <sect2 id="administration-ranking-static">
+ <title>Static Ranking</title>
- <para>
+ <para>
+ &zebra; uses internally inverted indexes to look up term frequencies
+ in documents. Multiple queries from different indexes can be
+ combined by the binary boolean operations <literal>AND</literal>,
+ <literal>OR</literal> and/or <literal>NOT</literal> (which
+ is in fact a binary <literal>AND NOT</literal> operation).
+ To ensure fast query execution
+ speed, all indexes have to be sorted in the same order.
+ </para>
+ <para>
+ The indexes are normally sorted according to document
+ <literal>ID</literal> in
+ ascending order, and any query which does not invoke a special
+ re-ranking function will therefore retrieve the result set in
+ document
+ <literal>ID</literal>
+ order.
+ </para>
+ <para>
+ If one defines the
+ <screen>
+ staticrank: 1
+ </screen>
+ directive in the main core &zebra; configuration file, the internal document
+ keys used for ordering are augmented by a preceding integer, which
+ contains the static rank of a given document, and the index lists
+ are ordered
+ first by ascending static rank,
+ then by ascending document <literal>ID</literal>.
+ Zero
+ is the ``best'' rank, as it occurs at the
+ beginning of the list; higher numbers represent worse scores.
+ </para>
+ <para>
+ The experimental <literal>alvis</literal> filter provides a
+ directive to fetch static rank information out of the indexed &acro.xml;
+ records, thus making <emphasis>all</emphasis> hit sets ordered
+ after <emphasis>ascending</emphasis> static
+ rank, and for those doc's which have the same static rank, ordered
+ after <emphasis>ascending</emphasis> doc <literal>ID</literal>.
+ See <xref linkend="record-model-alvisxslt"/> for the gory details.
+ </para>
+ </sect2>
- <screen>
- BEGIN { begin record wais }
-
- /^From:/ BODY /$/ { data -element name $1 }
- /^Subject:/ BODY /$/ { data -element title $1 }
- /^Date:/ BODY /$/ { data -element lastModified $1 }
- /\n\n/ BODY END {
- begin element bodyOfDisplay
- begin variant body iana "text/plain"
- data -text $1
- end record
- }
- </screen>
- </para>
+ <sect2 id="administration-ranking-dynamic">
+ <title>Dynamic Ranking</title>
+ <para>
+ In order to fiddle with the static rank order, it is necessary to
+ invoke additional re-ranking/re-ordering using dynamic
+ ranking or score functions. These functions return positive
+ integer scores, where <emphasis>highest</emphasis> score is
+ ``best'';
+ hit sets are sorted according to <emphasis>descending</emphasis>
+ scores (in contrary
+ to the index lists which are sorted according to
+ ascending rank number and document ID).
+ </para>
+ <para>
+ Dynamic ranking is enabled by a directive like one of the
+ following in the zebra configuration file (use only one of these a time!):
+ <screen>
+ rank: rank-1 # default TDF-IDF like
+ rank: rank-static # dummy do-nothing
+ </screen>
+ </para>
- <para>
- If Zebra is compiled with support for Tcl (Tool Command Language)
- enabled, the statements described above are supplemented with a complete
- scripting environment, including control structures (conditional
- expressions and loop constructs), and powerful string manipulation
- mechanisms for modifying the elements of a record. Tcl is a popular
- scripting environment, with several tutorials available both online
- and in hardcopy.
- </para>
+ <para>
+ Dynamic ranking is done at query time rather than
+ indexing time (this is why we
+ call it ``dynamic ranking'' in the first place ...)
+ It is invoked by adding
+ the &acro.bib1; relation attribute with
+ value ``relevance'' to the &acro.pqf; query (that is,
+ <literal>@attr 2=102</literal>, see also
+ <ulink url="&url.z39.50;bib1.html">
+ The &acro.bib1; Attribute Set Semantics</ulink>, also in
+ <ulink url="&url.z39.50.attset.bib1;">HTML</ulink>).
+ To find all articles with the word <literal>Eoraptor</literal> in
+ the title, and present them relevance ranked, issue the &acro.pqf; query:
+ <screen>
+ @attr 2=102 @attr 1=4 Eoraptor
+ </screen>
+ </para>
- <para>
- <emphasis>NOTE: Tcl support is not currently available, but will be
- included with one of the next alpha or beta releases.</emphasis>
- </para>
+ <sect3 id="administration-ranking-dynamic-rank1">
+ <title>Dynamically ranking using &acro.pqf; queries with the 'rank-1'
+ algorithm</title>
- <para>
- <emphasis>NOTE: Variant support is not currently available in the input
- filter, but will be included with one of the next alpha or beta
- releases.</emphasis>
- </para>
+ <para>
+ The default <literal>rank-1</literal> ranking module implements a
+ TF/IDF (Term Frequecy over Inverse Document Frequency) like
+ algorithm. In contrast to the usual definition of TF/IDF
+ algorithms, which only considers searching in one full-text
+ index, this one works on multiple indexes at the same time.
+ More precisely,
+ &zebra; does boolean queries and searches in specific addressed
+ indexes (there are inverted indexes pointing from terms in the
+ dictionary to documents and term positions inside documents).
+ It works like this:
+ <variablelist>
+ <varlistentry>
+ <term>Query Components</term>
+ <listitem>
+ <para>
+ First, the boolean query is dismantled into its principal components,
+ i.e. atomic queries where one term is looked up in one index.
+ For example, the query
+ <screen>
+ @attr 2=102 @and @attr 1=1010 Utah @attr 1=1018 Springer
+ </screen>
+ is a boolean AND between the atomic parts
+ <screen>
+ @attr 2=102 @attr 1=1010 Utah
+ </screen>
+ and
+ <screen>
+ @attr 2=102 @attr 1=1018 Springer
+ </screen>
+ which gets processed each for itself.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Atomic hit lists</term>
+ <listitem>
+ <para>
+ Second, for each atomic query, the hit list of documents is
+ computed.
+ </para>
+ <para>
+ In this example, two hit lists for each index
+ <literal>@attr 1=1010</literal> and
+ <literal>@attr 1=1018</literal> are computed.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Atomic scores</term>
+ <listitem>
+ <para>
+ Third, each document in the hit list is assigned a score (_if_ ranking
+ is enabled and requested in the query) using a TF/IDF scheme.
+ </para>
+ <para>
+ In this example, both atomic parts of the query assign the magic
+ <literal>@attr 2=102</literal> relevance attribute, and are
+ to be used in the relevance ranking functions.
+ </para>
+ <para>
+ It is possible to apply dynamic ranking on only parts of the
+ &acro.pqf; query:
+ <screen>
+ @and @attr 2=102 @attr 1=1010 Utah @attr 1=1018 Springer
+ </screen>
+ searches for all documents which have the term 'Utah' on the
+ body of text, and which have the term 'Springer' in the publisher
+ field, and sort them in the order of the relevance ranking made on
+ the body-of-text index only.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Hit list merging</term>
+ <listitem>
+ <para>
+ Fourth, the atomic hit lists are merged according to the boolean
+ conditions to a final hit list of documents to be returned.
+ </para>
+ <para>
+ This step is always performed, independently of the fact that
+ dynamic ranking is enabled or not.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Document score computation</term>
+ <listitem>
+ <para>
+ Fifth, the total score of a document is computed as a linear
+ combination of the atomic scores of the atomic hit lists
+ </para>
+ <para>
+ Ranking weights may be used to pass a value to a ranking
+ algorithm, using the non-standard &acro.bib1; attribute type 9.
+ This allows one branch of a query to use one value while
+ another branch uses a different one. For example, we can search
+ for <literal>utah</literal> in the
+ <literal>@attr 1=4</literal> index with weight 30, as
+ well as in the <literal>@attr 1=1010</literal> index with weight 20:
+ <screen>
+ @attr 2=102 @or @attr 9=30 @attr 1=4 utah @attr 9=20 @attr 1=1010 city
+ </screen>
+ </para>
+ <para>
+ The default weight is
+ sqrt(1000) ~ 34 , as the &acro.z3950; standard prescribes that the top score
+ is 1000 and the bottom score is 0, encoded in integers.
+ </para>
+ <warning>
+ <para>
+ The ranking-weight feature is experimental. It may change in future
+ releases of zebra.
+ </para>
+ </warning>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Re-sorting of hit list</term>
+ <listitem>
+ <para>
+ Finally, the final hit list is re-ordered according to scores.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
- </sect2>
+ </para>
- </sect1>
- <sect1 id="internal-representation">
- <title>Internal Representation</title>
+ <para>
+ The <literal>rank-1</literal> algorithm
+ does not use the static rank
+ information in the list keys, and will produce the same ordering
+ with or without static ranking enabled.
+ </para>
- <para>
- When records are manipulated by the system, they're represented in a
- tree-structure, with data elements at the leaf nodes, and tags or
- variant components at the non-leaf nodes. The root-node identifies the
- schema that lends context to the tagging and structuring of the
- record. Imagine a simple record, consisting of a 'title' element and
- an 'author' element:
- </para>
- <para>
+ <!--
+ <sect3 id="administration-ranking-dynamic-rank1">
+ <title>Dynamically ranking &acro.pqf; queries with the 'rank-static'
+ algorithm</title>
+ <para>
+ The dummy <literal>rank-static</literal> reranking/scoring
+ function returns just
+ <literal>score = max int - staticrank</literal>
+ in order to preserve the static ordering of hit sets that would
+ have been produced had it not been invoked.
+ Obviously, to combine static and dynamic ranking usefully,
+ it is necessary
+ to make a new ranking
+ function; this is left
+ as an exercise for the reader.
+ </para>
+ </sect3>
+ -->
- <screen>
- TITLE "Zen and the Art of Motorcycle Maintenance"
- ROOT
- AUTHOR "Robert Pirsig"
- </screen>
+ <warning>
+ <para>
+ <literal>Dynamic ranking</literal> is not compatible
+ with <literal>estimated hit sizes</literal>, as all documents in
+ a hit set must be accessed to compute the correct placing in a
+ ranking sorted list. Therefore the use attribute setting
+ <literal>@attr 2=102</literal> clashes with
+ <literal>@attr 9=integer</literal>.
+ </para>
+ </warning>
+
+ <!--
+ we might want to add ranking like this:
+ UNPUBLISHED:
+ Simple BM25 Extension to Multiple Weighted Fields
+ Stephen Robertson, Hugo Zaragoza and Michael Taylor
+ Microsoft Research
+ ser@microsoft.com
+ hugoz@microsoft.com
+ mitaylor2microsoft.com
+ -->
+
+ </sect3>
+
+ <sect3 id="administration-ranking-dynamic-cql">
+ <title>Dynamically ranking &acro.cql; queries</title>
+ <para>
+ Dynamic ranking can be enabled during sever side &acro.cql;
+ query expansion by adding <literal>@attr 2=102</literal>
+ chunks to the &acro.cql; config file. For example
+ <screen>
+ relationModifier.relevant = 2=102
+ </screen>
+ invokes dynamic ranking each time a &acro.cql; query of the form
+ <screen>
+ Z> querytype cql
+ Z> f alvis.text =/relevant house
+ </screen>
+ is issued. Dynamic ranking can also be automatically used on
+ specific &acro.cql; indexes by (for example) setting
+ <screen>
+ index.alvis.text = 1=text 2=102
+ </screen>
+ which then invokes dynamic ranking each time a &acro.cql; query of the form
+ <screen>
+ Z> querytype cql
+ Z> f alvis.text = house
+ </screen>
+ is issued.
+ </para>
- </para>
+ </sect3>
- <para>
- A slightly more complex record would have the author element consist
- of two elements, a surname and a first name:
- </para>
+ </sect2>
- <para>
- <screen>
- TITLE "Zen and the Art of Motorcycle Maintenance"
- ROOT
- FIRST-NAME "Robert"
- AUTHOR
- SURNAME "Pirsig"
- </screen>
-
- </para>
+ <sect2 id="administration-ranking-sorting">
+ <title>Sorting</title>
+ <para>
+ &zebra; sorts efficiently using special sorting indexes
+ (type=<literal>s</literal>; so each sortable index must be known
+ at indexing time, specified in the configuration of record
+ indexing. For example, to enable sorting according to the &acro.bib1;
+ <literal>Date/time-added-to-db</literal> field, one could add the line
+ <screen>
+ xelm /*/@created Date/time-added-to-db:s
+ </screen>
+ to any <literal>.abs</literal> record-indexing configuration file.
+ Similarly, one could add an indexing element of the form
+ <screen><![CDATA[
+ <z:index name="date-modified" type="s">
+ <xsl:value-of select="some/xpath"/>
+ </z:index>
+ ]]></screen>
+ to any <literal>alvis</literal>-filter indexing stylesheet.
+ </para>
+ <para>
+ Indexing can be specified at searching time using a query term
+ carrying the non-standard
+ &acro.bib1; attribute-type <literal>7</literal>. This removes the
+ need to send a &acro.z3950; <literal>Sort Request</literal>
+ separately, and can dramatically improve latency when the client
+ and server are on separate networks.
+ The sorting part of the query is separate from the rest of the
+ query - the actual search specification - and must be combined
+ with it using OR.
+ </para>
+ <para>
+ A sorting subquery needs two attributes: an index (such as a
+ &acro.bib1; type-1 attribute) specifying which index to sort on, and a
+ type-7 attribute whose value is be <literal>1</literal> for
+ ascending sorting, or <literal>2</literal> for descending. The
+ term associated with the sorting attribute is the priority of
+ the sort key, where <literal>0</literal> specifies the primary
+ sort key, <literal>1</literal> the secondary sort key, and so
+ on.
+ </para>
+ <para>For example, a search for water, sort by title (ascending),
+ is expressed by the &acro.pqf; query
+ <screen>
+ @or @attr 1=1016 water @attr 7=1 @attr 1=4 0
+ </screen>
+ whereas a search for water, sort by title ascending,
+ then date descending would be
+ <screen>
+ @or @or @attr 1=1016 water @attr 7=1 @attr 1=4 0 @attr 7=2 @attr 1=30 1
+ </screen>
+ </para>
+ <para>
+ Notice the fundamental differences between <literal>dynamic
+ ranking</literal> and <literal>sorting</literal>: there can be
+ only one ranking function defined and configured; but multiple
+ sorting indexes can be specified dynamically at search
+ time. Ranking does not need to use specific indexes, so
+ dynamic ranking can be enabled and disabled without
+ re-indexing; whereas, sorting indexes need to be
+ defined before indexing.
+ </para>
- <para>
- The root of the record will refer to the record schema that describes
- the structuring of this particular record. The schema defines the
- element tags (TITLE, FIRST-NAME, etc.) that may occur in the record, as
- well as the structuring (SURNAME should appear below AUTHOR, etc.). In
- addition, the schema establishes element set names that are used by
- the client to request a subset of the elements of a given record. The
- schema may also establish rules for converting the record to a
- different schema, by stating, for each element, a mapping to a
- different tag path.
- </para>
+ </sect2>
- <sect2>
- <title>Tagged Elements</title>
- <para>
- A data element is characterized by its tag, and its position in the
- structure of the record. For instance, while the tag "telephone
- number" may be used different places in a record, we may need to
- distinguish between these occurrences, both for searching and
- presentation purposes. For instance, while the phone numbers for the
- "customer" and the "service provider" are both
- representatives for the same type of resource (a telephone number), it
- is essential that they be kept separate. The record schema provides
- the structure of the record, and names each data element (defined by
- the sequence of tags - the tag path - by which the element can be
- reached from the root of the record).
- </para>
+ </sect1>
- </sect2>
+ <sect1 id="administration-extended-services">
+ <title>Extended Services: Remote Insert, Update and Delete</title>
- <sect2>
- <title>Variants</title>
+ <note>
+ <para>
+ Extended services are only supported when accessing the &zebra;
+ server using the <ulink url="&url.z39.50;">&acro.z3950;</ulink>
+ protocol. The <ulink url="&url.sru;">&acro.sru;</ulink> protocol does
+ not support extended services.
+ </para>
+ </note>
<para>
- The children of a tag node may be either more tag nodes, a data node
- (possibly accompanied by tag nodes),
- or a tree of variant nodes. The children of variant nodes are either
- more variant nodes or a data node (possibly accompanied by more
- variant nodes). Each leaf node, which is normally a
- data node, corresponds to a <emphasis>variant form</emphasis> of the
- tagged element identified by the tag which parents the variant tree.
- The following title element occurs in two different languages:
+ The extended services are not enabled by default in zebra - due to the
+ fact that they modify the system. &zebra; can be configured
+ to allow anybody to
+ search, and to allow only updates for a particular admin user
+ in the main zebra configuration file <filename>zebra.cfg</filename>.
+ For user <literal>admin</literal>, you could use:
+ <screen>
+ perm.anonymous: r
+ perm.admin: rw
+ passwd: passwordfile
+ </screen>
+ And in the password file
+ <filename>passwordfile</filename>, you have to specify users and
+ encrypted passwords as colon separated strings.
+ Use a tool like <filename>htpasswd</filename>
+ to maintain the encrypted passwords.
+ <screen>
+ admin:secret
+ </screen>
+ It is essential to configure &zebra; to store records internally,
+ and to support
+ modifications and deletion of records:
+ <screen>
+ storeData: 1
+ storeKeys: 1
+ </screen>
+ The general record type should be set to any record filter which
+ is able to parse &acro.xml; records, you may use any of the two
+ declarations (but not both simultaneously!)
+ <screen>
+ recordType: dom.filter_dom_conf.xml
+ # recordType: grs.xml
+ </screen>
+ Notice the difference to the specific instructions
+ <screen>
+ recordType.xml: dom.filter_dom_conf.xml
+ # recordType.xml: grs.xml
+ </screen>
+ which only work when indexing XML files from the filesystem using
+ the <literal>*.xml</literal> naming convention.
</para>
-
<para>
-
+ To enable transaction safe shadow indexing,
+ which is extra important for this kind of operation, set
<screen>
- VARIANT LANG=ENG "War and Peace"
- TITLE
- VARIANT LANG=DAN "Krig og Fred"
+ shadow: directoryname: size (e.g. 1000M)
</screen>
-
+ See <xref linkend="zebra-cfg"/> for additional information on
+ these configuration options.
</para>
+ <note>
+ <para>
+ It is not possible to carry information about record types or
+ similar to &zebra; when using extended services, due to
+ limitations of the <ulink url="&url.z39.50;">&acro.z3950;</ulink>
+ protocol. Therefore, indexing filters can not be chosen on a
+ per-record basis. One and only one general &acro.xml; indexing filter
+ must be defined.
+ <!-- but because it is represented as an OID, we would need some
+ form of proprietary mapping scheme between record type strings and
+ OIDs. -->
+ <!--
+ However, as a minimum, it would be extremely useful to enable
+ people to use &acro.marc21;, assuming grs.marcxml.marc21 as a record
+ type.
+ -->
+ </para>
+ </note>
- <para>
- Which of the two elements are transmitted to the client by the server
- depends on the specifications provided by the client, if any.
- </para>
- <para>
- In practice, each variant node is associated with a triple of class,
- type, value, corresponding to the variant mechanism of Z39.50.
- </para>
+ <sect2 id="administration-extended-services-z3950">
+ <title>Extended services in the &acro.z3950; protocol</title>
- </sect2>
+ <para>
+ The <ulink url="&url.z39.50;">&acro.z3950;</ulink> standard allows
+ servers to accept special binary <emphasis>extended services</emphasis>
+ protocol packages, which may be used to insert, update and delete
+ records into servers. These carry control and update
+ information to the servers, which are encoded in seven package fields:
+ </para>
- <sect2>
- <title>Data Elements</title>
+ <table id="administration-extended-services-z3950-table" frame="top">
+ <title>Extended services &acro.z3950; Package Fields</title>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Parameter</entry>
+ <entry>Value</entry>
+ <entry>Notes</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><literal>type</literal></entry>
+ <entry><literal>'update'</literal></entry>
+ <entry>Must be set to trigger extended services</entry>
+ </row>
+ <row>
+ <entry><literal>action</literal></entry>
+ <entry><literal>string</literal></entry>
+ <entry>
+ Extended service action type with
+ one of four possible values: <literal>recordInsert</literal>,
+ <literal>recordReplace</literal>,
+ <literal>recordDelete</literal>,
+ and <literal>specialUpdate</literal>
+ </entry>
+ </row>
+ <row>
+ <entry><literal>record</literal></entry>
+ <entry><literal>&acro.xml; string</literal></entry>
+ <entry>An &acro.xml; formatted string containing the record</entry>
+ </row>
+ <row>
+ <entry><literal>syntax</literal></entry>
+ <entry><literal>'xml'</literal></entry>
+ <entry>XML/SUTRS/MARC. GRS-1 not supported.
+ The default filter (record type) as given by recordType in
+ zebra.cfg is used to parse the record.</entry>
+ </row>
+ <row>
+ <entry><literal>recordIdOpaque</literal></entry>
+ <entry><literal>string</literal></entry>
+ <entry>
+ Optional client-supplied, opaque record
+ identifier used under insert operations.
+ </entry>
+ </row>
+ <row>
+ <entry><literal>recordIdNumber </literal></entry>
+ <entry><literal>positive number</literal></entry>
+ <entry>&zebra;'s internal system number,
+ not allowed for <literal>recordInsert</literal> or
+ <literal>specialUpdate</literal> actions which result in fresh
+ record inserts.
+ </entry>
+ </row>
+ <row>
+ <entry><literal>databaseName</literal></entry>
+ <entry><literal>database identifier</literal></entry>
+ <entry>
+ The name of the database to which the extended services should be
+ applied.
+ </entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
- <para>
- Data nodes have no children (they are always leaf nodes in the record
- tree).
- </para>
- <note>
<para>
- Documentation needs extension here about types of nodes - numerical,
- textual, etc., plus the various types of inclusion notes.
+ The <literal>action</literal> parameter can be any of
+ <literal>recordInsert</literal> (will fail if the record already exists),
+ <literal>recordReplace</literal> (will fail if the record does not exist),
+ <literal>recordDelete</literal> (will fail if the record does not
+ exist), and
+ <literal>specialUpdate</literal> (will insert or update the record
+ as needed, record deletion is not possible).
</para>
- </note>
-
- </sect2>
- </sect1>
+ <para>
+ During all actions, the
+ usual rules for internal record ID generation apply, unless an
+ optional <literal>recordIdNumber</literal> &zebra; internal ID or a
+ <literal>recordIdOpaque</literal> string identifier is assigned.
+ The default ID generation is
+ configured using the <literal>recordId:</literal> from
+ <filename>zebra.cfg</filename>.
+ See <xref linkend="zebra-cfg"/>.
+ </para>
- <sect1 id="data-model">
- <title>Configuring Your Data Model</title>
+ <para>
+ Setting of the <literal>recordIdNumber</literal> parameter,
+ which must be an existing &zebra; internal system ID number, is not
+ allowed during any <literal>recordInsert</literal> or
+ <literal>specialUpdate</literal> action resulting in fresh record
+ inserts.
+ </para>
- <para>
- The following sections describe the configuration files that govern
- the internal management of data records. The system searches for the files
- in the directories specified by the <emphasis>profilePath</emphasis>
- setting in the <literal>zebra.cfg</literal> file.
- </para>
+ <para>
+ When retrieving existing
+ records indexed with &acro.grs1; indexing filters, the &zebra; internal
+ ID number is returned in the field
+ <literal>/*/id:idzebra/localnumber</literal> in the namespace
+ <literal>xmlns:id="http://www.indexdata.dk/zebra/"</literal>,
+ where it can be picked up for later record updates or deletes.
+ </para>
- <sect2>
- <title>The Abstract Syntax</title>
+ <para>
+ A new element set for retrieval of internal record
+ data has been added, which can be used to access minimal records
+ containing only the <literal>recordIdNumber</literal> &zebra;
+ internal ID, or the <literal>recordIdOpaque</literal> string
+ identifier. This works for any indexing filter used.
+ See <xref linkend="special-retrieval"/>.
+ </para>
- <para>
- The abstract syntax definition (also known as an Abstract Record
- Structure, or ARS) is the focal point of the
- record schema description. For a given schema, the ABS file may state any
- or all of the following:
- </para>
+ <para>
+ The <literal>recordIdOpaque</literal> string parameter
+ is an client-supplied, opaque record
+ identifier, which may be used under
+ insert, update and delete operations. The
+ client software is responsible for assigning these to
+ records. This identifier will
+ replace zebra's own automagic identifier generation with a unique
+ mapping from <literal>recordIdOpaque</literal> to the
+ &zebra; internal <literal>recordIdNumber</literal>.
+ <emphasis>The opaque <literal>recordIdOpaque</literal> string
+ identifiers
+ are not visible in retrieval records, nor are
+ searchable, so the value of this parameter is
+ questionable. It serves mostly as a convenient mapping from
+ application domain string identifiers to &zebra; internal ID's.
+ </emphasis>
+ </para>
+ </sect2>
- <para>
- <itemizedlist>
- <listitem>
+ <sect2 id="administration-extended-services-yaz-client">
+ <title>Extended services from yaz-client</title>
- <para>
- The object identifier of the Z39.50 schema associated
- with the ARS, so that it can be referred to by the client.
- </para>
- </listitem>
+ <para>
+ We can now start a yaz-client admin session and create a database:
+ <screen>
+ <![CDATA[
+ $ yaz-client localhost:9999 -u admin/secret
+ Z> adm-create
+ ]]>
+ </screen>
+ Now the <literal>Default</literal> database was created,
+ we can insert an &acro.xml; file (esdd0006.grs
+ from example/gils/records) and index it:
+ <screen>
+ <![CDATA[
+ Z> update insert id1234 esdd0006.grs
+ ]]>
+ </screen>
+ The 3rd parameter - <literal>id1234</literal> here -
+ is the <literal>recordIdOpaque</literal> package field.
+ </para>
+ <para>
+ Actually, we should have a way to specify "no opaque record id" for
+ yaz-client's update command.. We'll fix that.
+ </para>
+ <para>
+ The newly inserted record can be searched as usual:
+ <screen>
+ <![CDATA[
+ Z> f utah
+ Sent searchRequest.
+ Received SearchResponse.
+ Search was a success.
+ Number of hits: 1, setno 1
+ SearchResult-1: term=utah cnt=1
+ records returned: 0
+ Elapsed: 0.014179
+ ]]>
+ </screen>
+ </para>
+ <para>
+ Let's delete the beast, using the same
+ <literal>recordIdOpaque</literal> string parameter:
+ <screen>
+ <![CDATA[
+ Z> update delete id1234
+ No last record (update ignored)
+ Z> update delete 1 esdd0006.grs
+ Got extended services response
+ Status: done
+ Elapsed: 0.072441
+ Z> f utah
+ Sent searchRequest.
+ Received SearchResponse.
+ Search was a success.
+ Number of hits: 0, setno 2
+ SearchResult-1: term=utah cnt=0
+ records returned: 0
+ Elapsed: 0.013610
+ ]]>
+ </screen>
+ </para>
+ <para>
+ If shadow register is enabled in your
+ <filename>zebra.cfg</filename>,
+ you must run the adm-commit command
+ <screen>
+ <![CDATA[
+ Z> adm-commit
+ ]]>
+ </screen>
+ after each update session in order write your changes from the
+ shadow to the life register space.
+ </para>
+ </sect2>
- <listitem>
- <para>
- The attribute set (which can possibly be a compound of multiple
- sets) which applies in the profile. This is used when indexing and
- searching the records belonging to the given profile.
- </para>
- </listitem>
- <listitem>
- <para>
- The Tag set (again, this can consist of several different sets).
- This is used when reading the records from a file, to recognize the
- different tags, and when transmitting the record to the client -
- mapping the tags to their numerical representation, if they are
- known.
- </para>
- </listitem>
+ <sect2 id="administration-extended-services-yaz-php">
+ <title>Extended services from yaz-php</title>
+
+ <para>
+ Extended services are also available from the &yaz; &acro.php; client layer. An
+ example of an &yaz;-&acro.php; extended service transaction is given here:
+ <screen>
+ <![CDATA[
+ $record = '<record><title>A fine specimen of a record</title></record>';
+
+ $options = array('action' => 'recordInsert',
+ 'syntax' => 'xml',
+ 'record' => $record,
+ 'databaseName' => 'mydatabase'
+ );
+
+ yaz_es($yaz, 'update', $options);
+ yaz_es($yaz, 'commit', array());
+ yaz_wait();
+
+ if ($error = yaz_error($yaz))
+ echo "$error";
+ ]]>
+ </screen>
+ </para>
+ </sect2>
+
+ <sect2 id="administration-extended-services-debugging">
+ <title>Extended services debugging guide</title>
+ <para>
+ When debugging ES over PHP we recommend the following order of tests:
+ </para>
+ <itemizedlist>
<listitem>
<para>
- The variant set which is used in the profile. This provides a
- vocabulary for specifying the <emphasis>forms</emphasis> of data that appear inside
- the records.
+ Make sure you have a nice record on your filesystem, which you can
+ index from the filesystem by use of the zebraidx command.
+ Do it exactly as you planned, using one of the GRS-1 filters,
+ or the DOMXML filter.
+ When this works, proceed.
</para>
</listitem>
-
<listitem>
<para>
- Element set names, which are a shorthand way for the client to
- ask for a subset of the data elements contained in a record. Element
- set names, in the retrieval module, are mapped to <emphasis>element
- specifications</emphasis>, which contain information equivalent to the
- <emphasis>Espec-1</emphasis> syntax of Z39.50.
+ Check that your server setup is OK before you even coded one single
+ line PHP using ES.
+ Take the same record form the file system, and send as ES via
+ <literal>yaz-client</literal> like described in
+ <xref linkend="administration-extended-services-yaz-client"/>,
+ and
+ remember the <literal>-a</literal> option which tells you what
+ goes over the wire! Notice also the section on permissions:
+ try
+ <screen>
+ perm.anonymous: rw
+ </screen>
+ in <literal>zebra.cfg</literal> to make sure you do not run into
+ permission problems (but never expose such an insecure setup on the
+ internet!!!). Then, make sure to set the general
+ <literal>recordType</literal> instruction, pointing correctly
+ to the GRS-1 filters,
+ or the DOMXML filters.
</para>
</listitem>
-
<listitem>
<para>
- Map tables, which may specify mappings to
- <emphasis>other</emphasis> database profiles, if desired.
+ If you insist on using the <literal>sysno</literal> in the
+ <literal>recordIdNumber</literal> setting,
+ please make sure you do only updates and deletes. Zebra's internal
+ system number is not allowed for
+ <literal>recordInsert</literal> or
+ <literal>specialUpdate</literal> actions
+ which result in fresh record inserts.
</para>
</listitem>
-
<listitem>
<para>
- Possibly, a set of rules describing the mapping of elements to a
- MARC representation.
-
+ If <literal>shadow register</literal> is enabled in your
+ <literal>zebra.cfg</literal>, you must remember running the
+ <screen>
+ Z> adm-commit
+ </screen>
+ command as well.
</para>
</listitem>
-
- <listitem>
+ <listitem>
<para>
- A list of element descriptions (this is the actual ARS of the
- schema, in Z39.50 terms), which lists the ways in which the various
- tags can be used and organized hierarchically.
+ If this works, then proceed to do the same thing in your PHP script.
</para>
</listitem>
-
</itemizedlist>
- </para>
-
- <para>
- Several of the entries above simply refer to other files, which
- describe the given objects.
- </para>
-
- </sect2>
-
- <sect2>
- <title>The Configuration Files</title>
-
- <para>
- This section describes the syntax and use of the various tables which
- are used by the retrieval module.
- </para>
-
- <para>
- The number of different file types may appear daunting at first, but
- each type corresponds fairly clearly to a single aspect of the Z39.50
- retrieval facilities. Further, the average database administrator,
- who is simply reusing an existing profile for which tables already
- exist, shouldn't have to worry too much about the contents of these tables.
- </para>
-
- <para>
- Generally, the files are simple ASCII files, which can be maintained
- using any text editor. Blank lines, and lines beginning with a (#) are
- ignored. Any characters on a line followed by a (#) are also ignored.
- All other lines contain <emphasis>directives</emphasis>, which provide
- some setting or value to the system.
- Generally, settings are characterized by a single
- keyword, identifying the setting, followed by a number of parameters.
- Some settings are repeatable (r), while others may occur only once in a
- file. Some settings are optional (o), whicle others again are
- mandatory (m).
- </para>
-
- </sect2>
-
- <sect2>
- <title>The Abstract Syntax (.abs) Files</title>
-
- <para>
- The name of this file type is slightly misleading in Z39.50 terms,
- since, apart from the actual abstract syntax of the profile, it also
- includes most of the other definitions that go into a database
- profile.
- </para>
-
- <para>
- When a record in the canonical, SGML-like format is read from a file
- or from the database, the first tag of the file should reference the
- profile that governs the layout of the record. If the first tag of the
- record is, say, <literal><gils></literal>, the system will look
- for the profile definition in the file <literal>gils.abs</literal>.
- Profile definitions are cached, so they only have to be read once
- during the lifespan of the current process.
- </para>
-
- <para>
- When writing your own input filters, the
- <emphasis>record-begin</emphasis> command
- introduces the profile, and should always be called first thing when
- introducing a new record.
- </para>
-
- <para>
- The file may contain the following directives:
- </para>
-
- <para>
- <variablelist>
-
- <varlistentry>
- <term>name <emphasis>symbolic-name</emphasis></term>
- <listitem>
- <para>
- (m) This provides a shorthand name or
- description for the profile. Mostly useful for diagnostic purposes.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>reference <emphasis>OID-name</emphasis></term>
- <listitem>
- <para>
- (m) The reference name of the OID for the profile.
- The reference names can be found in the <emphasis>util</emphasis>
- module of <emphasis>YAZ</emphasis>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>attset <emphasis>filename</emphasis></term>
- <listitem>
- <para>
- (m) The attribute set that is used for
- indexing and searching records belonging to this profile.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>tagset <emphasis>filename</emphasis></term>
- <listitem>
- <para>
- (o) The tag set (if any) that describe
- that fields of the records.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>varset <emphasis>filename</emphasis></term>
- <listitem>
- <para>
- (o) The variant set used in the profile.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>maptab <emphasis>filename</emphasis></term>
- <listitem>
- <para>
- (o,r) This points to a
- conversion table that might be used if the client asks for the record
- in a different schema from the native one.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>marc <emphasis>filename</emphasis></term>
- <listitem>
- <para>
- (o) Points to a file containing parameters
- for representing the record contents in the ISO2709 syntax. Read the
- description of the MARC representation facility below.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>esetname <emphasis>name filename</emphasis></term>
- <listitem>
- <para>
- (o,r) Associates the
- given element set name with an element selection file. If an (@) is
- given in place of the filename, this corresponds to a null mapping for
- the given element set name.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>any <emphasis>tags</emphasis></term>
- <listitem>
- <para>
- (o) This directive specifies a list of attributes
- which should be appended to the attribute list given for each
- element. The effect is to make every single element in the abstract
- syntax searchable by way of the given attributes. This directive
- provides an efficient way of supporting free-text searching across all
- elements. However, it does increase the size of the index
- significantly. The attributes can be qualified with a structure, as in
- the <emphasis>elm</emphasis> directive below.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>elm <emphasis>path name attributes</emphasis></term>
- <listitem>
- <para>
- (o,r) Adds an element to the abstract record syntax of the schema.
- The <emphasis>path</emphasis> follows the
- syntax which is suggested by the Z39.50 document - that is, a sequence
- of tags separated by slashes (/). Each tag is given as a
- comma-separated pair of tag type and -value surrounded by parenthesis.
- The <emphasis>name</emphasis> is the name of the element, and
- the <emphasis>attributes</emphasis>
- specifies which attributes to use when indexing the element in a
- comma-separated list.
- A ! in place of the attribute name is equivalent to
- specifying an attribute name identical to the element name.
- A - in place of the attribute name
- specifies that no indexing is to take place for the given element.
- The attributes can be qualified with <emphasis>field
- types</emphasis> to specify which
- character set should govern the indexing procedure for that field.
- The same data element may be indexed into several different
- fields, using different character set definitions.
- See the section <xref linkend="field-structure-and-character-sets"/>.
- The default field type is "w" for <emphasis>word</emphasis>.
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- <note>
- <para>
- The mechanism for controlling indexing is not adequate for
- complex databases, and will probably be moved into a separate
- configuration table eventually.
- </para>
- </note>
-
- <para>
- The following is an excerpt from the abstract syntax file for the GILS
- profile.
- </para>
-
- <para>
-
- <screen>
- name gils
- reference GILS-schema
- attset gils.att
- tagset gils.tag
- varset var1.var
-
- maptab gils-usmarc.map
-
- # Element set names
-
- esetname VARIANT gils-variant.est # for WAIS-compliance
- esetname B gils-b.est
- esetname G gils-g.est
- esetname F @
-
- elm (1,10) rank -
- elm (1,12) url -
- elm (1,14) localControlNumber Local-number
- elm (1,16) dateOfLastModification Date/time-last-modified
- elm (2,1) title w:!,p:!
- elm (4,1) controlIdentifier Identifier-standard
- elm (2,6) abstract Abstract
- elm (4,51) purpose !
- elm (4,52) originator -
- elm (4,53) accessConstraints !
- elm (4,54) useConstraints !
- elm (4,70) availability -
- elm (4,70)/(4,90) distributor -
- elm (4,70)/(4,90)/(2,7) distributorName !
- elm (4,70)/(4,90)/(2,10 distributorOrganization !
- elm (4,70)/(4,90)/(4,2) distributorStreetAddress !
- elm (4,70)/(4,90)/(4,3) distributorCity !
- </screen>
-
- </para>
-
- </sect2>
-
- <sect2 id="attset-files">
- <title>The Attribute Set (.att) Files</title>
-
- <para>
- This file type describes the <emphasis>Use</emphasis> elements of
- an attribute set.
- It contains the following directives.
- </para>
-
- <para>
- <variablelist>
- <varlistentry>
- <term>name <emphasis>symbolic-name</emphasis></term>
- <listitem>
- <para>
- (m) This provides a shorthand name or
- description for the attribute set.
- Mostly useful for diagnostic purposes.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>reference <emphasis>OID-name</emphasis></term>
- <listitem>
- <para>
- (m) The reference name of the OID for
- the attribute set.
- The reference names can be found in the <emphasis>util</emphasis>
- module of <emphasis>YAZ</emphasis>.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>include <emphasis>filename</emphasis></term>
- <listitem>
- <para>
- (o,r) This directive is used to
- include another attribute set as a part of the current one. This is
- used when a new attribute set is defined as an extension to another
- set. For instance, many new attribute sets are defined as extensions
- to the <emphasis>bib-1</emphasis> set.
- This is an important feature of the retrieval
- system of Z39.50, as it ensures the highest possible level of
- interoperability, as those access points of your database which are
- derived from the external set (say, bib-1) can be used even by clients
- who are unaware of the new set.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>att
- <emphasis>att-value att-name [local-value]</emphasis></term>
- <listitem>
- <para>
- (o,r) This
- repeatable directive introduces a new attribute to the set. The
- attribute value is stored in the index (unless a
- <emphasis>local-value</emphasis> is
- given, in which case this is stored). The name is used to refer to the
- attribute from the <emphasis>abstract syntax</emphasis>.
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- <para>
- This is an excerpt from the GILS attribute set definition.
- Notice how the file describing the <emphasis>bib-1</emphasis>
- attribute set is referenced.
- </para>
-
- <para>
-
- <screen>
- name gils
- reference GILS-attset
- include bib1.att
-
- att 2001 distributorName
- att 2002 indextermsControlled
- att 2003 purpose
- att 2004 accessConstraints
- att 2005 useConstraints
- </screen>
-
- </para>
-
- </sect2>
-
- <sect2>
- <title>The Tag Set (.tag) Files</title>
-
- <para>
- This file type defines the tagset of the profile, possibly by
- referencing other tag sets (most tag sets, for instance, will include
- tagsetG and tagsetM from the Z39.50 specification. The file may
- contain the following directives.
- </para>
-
- <para>
- <variablelist>
-
- <varlistentry>
- <term>name <emphasis>symbolic-name</emphasis></term>
- <listitem>
- <para>
- (m) This provides a shorthand name or
- description for the tag set. Mostly useful for diagnostic purposes.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>reference <emphasis>OID-name</emphasis></term>
- <listitem>
- <para>
- (o) The reference name of the OID for the tag set.
- The reference names can be found in the <emphasis>util</emphasis>
- module of <emphasis>YAZ</emphasis>.
- The directive is optional, since not all tag sets
- are registered outside of their schema.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>type <emphasis>integer</emphasis></term>
- <listitem>
- <para>
- (m) The type number of the tagset within the schema
- profile (note: this specification really should belong to the .abs
- file. This will be fixed in a future release).
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>include <emphasis>filename</emphasis></term>
- <listitem>
- <para>
- (o,r) This directive is used
- to include the definitions of other tag sets into the current one.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>tag <emphasis>number names type</emphasis></term>
- <listitem>
- <para>
- (o,r) Introduces a new tag to the set.
- The <emphasis>number</emphasis> is the tag number as used
- in the protocol (there is currently no mechanism for
- specifying string tags at this point, but this would be quick
- work to add).
- The <emphasis>names</emphasis> parameter is a list of names
- by which the tag should be recognized in the input file format.
- The names should be separated by slashes (/).
- The <emphasis>type</emphasis> is th recommended datatype of
- the tag.
- It should be one of the following:
-
- <itemizedlist>
- <listitem>
- <para>
- structured
- </para>
- </listitem>
-
- <listitem>
- <para>
- string
- </para>
- </listitem>
-
- <listitem>
- <para>
- numeric
- </para>
- </listitem>
-
- <listitem>
- <para>
- bool
- </para>
- </listitem>
-
- <listitem>
- <para>
- oid
- </para>
- </listitem>
-
- <listitem>
- <para>
- generalizedtime
- </para>
- </listitem>
-
- <listitem>
- <para>
- intunit
- </para>
- </listitem>
-
- <listitem>
- <para>
- int
- </para>
- </listitem>
-
- <listitem>
- <para>
- octetstring
- </para>
- </listitem>
-
- <listitem>
- <para>
- null
- </para>
- </listitem>
-
- </itemizedlist>
-
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- <para>
- The following is an excerpt from the TagsetG definition file.
- </para>
-
- <para>
- <screen>
- name tagsetg
- reference TagsetG
- type 2
-
- tag 1 title string
- tag 2 author string
- tag 3 publicationPlace string
- tag 4 publicationDate string
- tag 5 documentId string
- tag 6 abstract string
- tag 7 name string
- tag 8 date generalizedtime
- tag 9 bodyOfDisplay string
- tag 10 organization string
- </screen>
- </para>
-
- </sect2>
-
- <sect2 id="variant-set">
- <title>The Variant Set (.var) Files</title>
-
- <para>
- The variant set file is a straightforward representation of the
- variant set definitions associated with the protocol. At present, only
- the <emphasis>Variant-1</emphasis> set is known.
- </para>
-
- <para>
- These are the directives allowed in the file.
- </para>
-
- <para>
- <variablelist>
-
- <varlistentry>
- <term>name <emphasis>symbolic-name</emphasis></term>
- <listitem>
- <para>
- (m) This provides a shorthand name or
- description for the variant set. Mostly useful for diagnostic purposes.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>reference <emphasis>OID-name</emphasis></term>
- <listitem>
- <para>
- (o) The reference name of the OID for
- the variant set, if one is required. The reference names can be found
- in the <emphasis>util</emphasis> module of <emphasis>YAZ</emphasis>.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>class <emphasis>integer class-name</emphasis></term>
- <listitem>
- <para>
- (m,r) Introduces a new
- class to the variant set.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>type <emphasis>integer type-name datatype</emphasis></term>
- <listitem>
- <para>
- (m,r) Addes a
- new type to the current class (the one introduced by the most recent
- <emphasis>class</emphasis> directive).
- The type names belong to the same name space as the one used
- in the tag set definition file.
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- <para>
- The following is an excerpt from the file describing the variant set
- <emphasis>Variant-1</emphasis>.
- </para>
-
- <para>
-
- <screen>
- name variant-1
- reference Variant-1
-
- class 1 variantId
-
- type 1 variantId octetstring
-
- class 2 body
-
- type 1 iana string
- type 2 z39.50 string
- type 3 other string
- </screen>
-
- </para>
-
- </sect2>
-
- <sect2>
- <title>The Element Set (.est) Files</title>
-
- <para>
- The element set specification files describe a selection of a subset
- of the elements of a database record. The element selection mechanism
- is equivalent to the one supplied by the <emphasis>Espec-1</emphasis>
- syntax of the Z39.50 specification.
- In fact, the internal representation of an element set
- specification is identical to the <emphasis>Espec-1</emphasis> structure,
- and we'll refer you to the description of that structure for most of
- the detailed semantics of the directives below.
- </para>
-
- <note>
- <para>
- Not all of the Espec-1 functionality has been implemented yet.
- The fields that are mentioned below all work as expected, unless
- otherwise is noted.
- </para>
- </note>
-
- <para>
- The directives available in the element set file are as follows:
- </para>
-
- <para>
- <variablelist>
- <varlistentry>
- <term>defaultVariantSetId <emphasis>OID-name</emphasis></term>
- <listitem>
- <para>
- (o) If variants are used in
- the following, this should provide the name of the variantset used
- (it's not currently possible to specify a different set in the
- individual variant request). In almost all cases (certainly all
- profiles known to us), the name
- <literal>Variant-1</literal> should be given here.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>defaultVariantRequest <emphasis>variant-request</emphasis></term>
- <listitem>
- <para>
- (o) This directive
- provides a default variant request for
- use when the individual element requests (see below) do not contain a
- variant request. Variant requests consist of a blank-separated list of
- variant components. A variant compont is a comma-separated,
- parenthesized triple of variant class, type, and value (the two former
- values being represented as integers). The value can currently only be
- entered as a string (this will change to depend on the definition of
- the variant in question). The special value (@) is interpreted as a
- null value, however.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>simpleElement
- <emphasis>path ['variant' variant-request]</emphasis></term>
- <listitem>
- <para>
- (o,r) This corresponds to a simple element request
- in <emphasis>Espec-1</emphasis>.
- The path consists of a sequence of tag-selectors, where each of
- these can consist of either:
- </para>
-
- <para>
- <itemizedlist>
- <listitem>
- <para>
- A simple tag, consisting of a comma-separated type-value pair in
- parenthesis, possibly followed by a colon (:) followed by an
- occurrences-specification (see below). The tag-value can be a number
- or a string. If the first character is an apostrophe ('), this
- forces the value to be interpreted as a string, even if it
- appears to be numerical.
- </para>
- </listitem>
-
- <listitem>
- <para>
- A WildThing, represented as a question mark (?), possibly
- followed by a colon (:) followed by an occurrences
- specification (see below).
- </para>
- </listitem>
-
- <listitem>
- <para>
- A WildPath, represented as an asterisk (*). Note that the last
- element of the path should not be a wildPath (wildpaths don't
- work in this version).
- </para>
- </listitem>
-
- </itemizedlist>
-
- </para>
-
- <para>
- The occurrences-specification can be either the string
- <literal>all</literal>, the string <literal>last</literal>, or
- an explicit value-range. The value-range is represented as
- an integer (the starting point), possibly followed by a
- plus (+) and a second integer (the number of elements, default
- being one).
- </para>
-
- <para>
- The variant-request has the same syntax as the defaultVariantRequest
- above. Note that it may sometimes be useful to give an empty variant
- request, simply to disable the default for a specific set of fields
- (we aren't certain if this is proper <emphasis>Espec-1</emphasis>,
- but it works in this implementation).
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- <para>
- The following is an example of an element specification belonging to
- the GILS profile.
- </para>
-
- <para>
-
- <screen>
- simpleelement (1,10)
- simpleelement (1,12)
- simpleelement (2,1)
- simpleelement (1,14)
- simpleelement (4,1)
- simpleelement (4,52)
- </screen>
-
- </para>
-
- </sect2>
-
- <sect2 id="schema-mapping">
- <title>The Schema Mapping (.map) Files</title>
-
- <para>
- Sometimes, the client might want to receive a database record in
- a schema that differs from the native schema of the record. For
- instance, a client might only know how to process WAIS records, while
- the database record is represented in a more specific schema, such as
- GILS. In this module, a mapping of data to one of the MARC formats is
- also thought of as a schema mapping (mapping the elements of the
- record into fields consistent with the given MARC specification, prior
- to actually converting the data to the ISO2709). This use of the
- object identifier for USMARC as a schema identifier represents an
- overloading of the OID which might not be entirely proper. However,
- it represents the dual role of schema and record syntax which
- is assumed by the MARC family in Z39.50.
- </para>
-
- <para>
- <emphasis>NOTE: The schema-mapping functions are so far limited to a
- straightforward mapping of elements. This should be extended with
- mechanisms for conversions of the element contents, and conditional
- mappings of elements based on the record contents.</emphasis>
- </para>
-
- <para>
- These are the directives of the schema mapping file format:
- </para>
-
- <para>
- <variablelist>
-
- <varlistentry>
- <term>targetName <emphasis>name</emphasis></term>
- <listitem>
- <para>
- (m) A symbolic name for the target schema
- of the table. Useful mostly for diagnostic purposes.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>targetRef <emphasis>OID-name</emphasis></term>
- <listitem>
- <para>
- (m) An OID name for the target schema.
- This is used, for instance, by a server receiving a request to present
- a record in a different schema from the native one.
- The name, again, is found in the <emphasis>oid</emphasis>
- module of <emphasis>YAZ</emphasis>.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>map <emphasis>element-name target-path</emphasis></term>
- <listitem>
- <para>
- (o,r) Adds
- an element mapping rule to the table.
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- </sect2>
-
- <sect2>
- <title>The MARC (ISO2709) Representation (.mar) Files</title>
- <para>
- This file provides rules for representing a record in the ISO2709
- format. The rules pertain mostly to the values of the constant-length
- header of the record.
- </para>
-
- <para>
- <emphasis>NOTE: This will be described better. We're in the process of
- re-evaluating and most likely changing the way that MARC records are
- handled by the system.</emphasis>
- </para>
-
- </sect2>
-
- <sect2 id="field-structure-and-character-sets">
- <title>Field Structure and Character Sets
- </title>
-
- <para>
- In order to provide a flexible approach to national character set
- handling, Zebra allows the administrator to configure the set up the
- system to handle any 8-bit character set — including sets that
- require multi-octet diacritics or other multi-octet characters. The
- definition of a character set includes a specification of the
- permissible values, their sort order (this affects the display in the
- SCAN function), and relationships between upper- and lowercase
- characters. Finally, the definition includes the specification of
- space characters for the set.
- </para>
-
- <para>
- The operator can define different character sets for different fields,
- typical examples being standard text fields, numerical fields, and
- special-purpose fields such as WWW-style linkages (URx).
- </para>
-
- <para>
- The field types, and hence character sets, are associated with data
- elements by the .abs files (see above).
- The file <literal>default.idx</literal>
- provides the association between field type codes (as used in the .abs
- files) and the character map files (with the .chr suffix). The format
- of the .idx file is as follows
- </para>
+ </sect2>
- <para>
- <variablelist>
-
- <varlistentry>
- <term>index <emphasis>field type code</emphasis></term>
- <listitem>
- <para>
- This directive introduces a new search index code.
- The argument is a one-character code to be used in the
- .abs files to select this particular index type. An index, roughly,
- corresponds to a particular structure attribute during search. Refer
- to section <xref linkend="search"/>.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>sort <emphasis>field code type</emphasis></term>
- <listitem>
- <para>
- This directive introduces a
- sort index. The argument is a one-character code to be used in the
- .abs fie to select this particular index type. The corresponding
- use attribute must be used in the sort request to refer to this
- particular sort index. The corresponding character map (see below)
- is used in the sort process.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>completeness <emphasis>boolean</emphasis></term>
- <listitem>
- <para>
- This directive enables or disables complete field indexing.
- The value of the <emphasis>boolean</emphasis> should be 0
- (disable) or 1. If completeness is enabled, the index entry will
- contain the complete contents of the field (up to a limit), with words
- (non-space characters) separated by single space characters
- (normalized to " " on display). When completeness is
- disabled, each word is indexed as a separate entry. Complete subfield
- indexing is most useful for fields which are typically browsed (eg.
- titles, authors, or subjects), or instances where a match on a
- complete subfield is essential (eg. exact title searching). For fields
- where completeness is disabled, the search engine will interpret a
- search containing space characters as a word proximity search.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>charmap <emphasis>filename</emphasis></term>
- <listitem>
- <para>
- This is the filename of the character
- map to be used for this index for field type.
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- <para>
- The contents of the character map files are structured as follows:
- </para>
-
- <para>
- <variablelist>
-
- <varlistentry>
- <term>lowercase <emphasis>value-set</emphasis></term>
- <listitem>
- <para>
- This directive introduces the basic value set of the field type.
- The format is an ordered list (without spaces) of the
- characters which may occur in "words" of the given type.
- The order of the entries in the list determines the
- sort order of the index. In addition to single characters, the
- following combinations are legal:
- </para>
-
- <para>
-
- <itemizedlist>
- <listitem>
- <para>
- Backslashes may be used to introduce three-digit octal, or
- two-digit hex representations of single characters
- (preceded by <literal>x</literal>).
- In addition, the combinations
- \\, \\r, \\n, \\t, \\s (space — remember that real
- space-characters may ot occur in the value definition), and
- \\ are recognised, with their usual interpretation.
- </para>
- </listitem>
-
- <listitem>
- <para>
- Curly braces {} may be used to enclose ranges of single
- characters (possibly using the escape convention described in the
- preceding point), eg. {a-z} to entroduce the
- standard range of ASCII characters.
- Note that the interpretation of such a range depends on
- the concrete representation in your local, physical character set.
- </para>
- </listitem>
-
- <listitem>
- <para>
- paranthesises () may be used to enclose multi-byte characters -
- eg. diacritics or special national combinations (eg. Spanish
- "ll"). When found in the input stream (or a search term),
- these characters are viewed and sorted as a single character, with a
- sorting value depending on the position of the group in the value
- statement.
- </para>
- </listitem>
-
- </itemizedlist>
-
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>uppercase <emphasis>value-set</emphasis></term>
- <listitem>
- <para>
- This directive introduces the
- upper-case equivalencis to the value set (if any). The number and
- order of the entries in the list should be the same as in the
- <literal>lowercase</literal> directive.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>space <emphasis>value-set</emphasis></term>
- <listitem>
- <para>
- This directive introduces the character
- which separate words in the input stream. Depending on the
- completeness mode of the field in question, these characters either
- terminate an index entry, or delimit individual "words" in
- the input stream. The order of the elements is not significant —
- otherwise the representation is the same as for the
- <literal>uppercase</literal> and <literal>lowercase</literal>
- directives.
- </para>
- </listitem></varlistentry>
- <varlistentry>
- <term>map <emphasis>value-set</emphasis>
- <emphasis>target</emphasis></term>
- <listitem>
- <para>
- This directive introduces a
- mapping between each of the members of the value-set on the left to
- the character on the right. The character on the right must occur in
- the value set (the <literal>lowercase</literal> directive) of
- the character set, but
- it may be a paranthesis-enclosed multi-octet character. This directive
- may be used to map diacritics to their base characters, or to map
- HTML-style character-representations to their natural form, etc.
- </para>
- </listitem></varlistentry>
- </variablelist>
- </para>
-
- </sect2>
-
- </sect1>
-
- <sect1 id="formats">
- <title>Exchange Formats</title>
-
- <para>
- Converting records from the internal structure to en exchange format
- is largely an automatic process. Currently, the following exchange
- formats are supported:
- </para>
-
- <para>
- <itemizedlist>
- <listitem>
- <para>
- GRS-1. The internal representation is based on GRS-1, so the
- conversion here is straightforward. The system will create
- applied variant and supported variant lists as required, if a record
- contains variant information.
- </para>
- </listitem>
-
- <listitem>
- <para>
- SUTRS. Again, the mapping is fairly straighforward. Indentation
- is used to show the hierarchical structure of the record. All
- "GRS" type records support both the GRS-1 and SUTRS
- representations.
- </para>
- </listitem>
-
- <listitem>
- <para>
- ISO2709-based formats (USMARC, etc.). Only records with a
- two-level structure (corresponding to fields and subfields) can be
- directly mapped to ISO2709. For records with a different structuring
- (eg., GILS), the representation in a structure like USMARC involves a
- schema-mapping (see section <xref linkend="schema-mapping"/>), to an
- "implied" USMARC schema (implied,
- because there is no formal schema which specifies the use of the
- USMARC fields outside of ISO2709). The resultant, two-level record is
- then mapped directly from the internal representation to ISO2709. See
- the GILS schema definition files for a detailed example of this
- approach.
- </para>
- </listitem>
-
- <listitem>
- <para>
- Explain. This representation is only available for records
- belonging to the Explain schema.
- </para>
- </listitem>
-
- <listitem>
- <para>
- Summary. This ASN-1 based structure is only available for records
- belonging to the Summary schema - or schema which provide a mapping
- to this schema (see the description of the schema mapping facility
- above).
- </para>
- </listitem>
-
- <listitem>
- <para>
- SOIF. Support for this syntax is experimental, and is currently
- keyed to a private Index Data OID (1.2.840.10003.5.1000.81.2). All
- abstract syntaxes can be mapped to the SOIF format, although nested
- elements are represented by concatenation of the tag names at each
- level.
- </para>
- </listitem>
-
- </itemizedlist>
-
- </para>
+ </sect1>
- </sect1>
+ </chapter>
-</chapter>
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