X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;f=doc%2Fadministration.xml;h=dca0506281701ef62e740cbf9d123f62badd5762;hb=3e8db66d56c466a5a269362eb70b4931d9579128;hp=fd1e8f41513e9c9917d014f9500ef9397f681325;hpb=dd8372e3f27c68a0410f13044dd184ccde8ca243;p=idzebra-moved-to-github.git
diff --git a/doc/administration.xml b/doc/administration.xml
index fd1e8f4..dca0506 100644
--- a/doc/administration.xml
+++ b/doc/administration.xml
@@ -1,120 +1,13 @@
-
- Quick Start
-
-
- 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
- test/gils subdirectory of the distribution archive.
- There you will find a configuration
- file named zebra.cfg with the following contents:
-
-
- # Where are the YAZ tables located.
- profilePath: ../../../yaz/tab ../../tab
-
- # Files that describe the attribute sets supported.
- attset: bib1.att
- attset: gils.att
-
-
-
-
- Now, edit the file and set profilePath to the path of the
- YAZ profile tables (sub directory tab of the YAZ
- distribution archive).
-
-
-
- The 48 test records are located in the sub directory
- records. To index these, type:
-
-
- $ ../../index/zebraidx -t grs.sgml update records
-
-
-
-
- In the command above the option -t specified the record
- type — in this case grs.sgml.
- The word update followed
- by a directory root updates all files below that directory node.
-
-
-
- If your indexing command was successful, you are now ready to
- fire up a server. To start a server on port 2100, type:
-
-
- $ ../../index/zebrasrv tcp:@:2100
-
-
-
-
-
- The Zebra index that you have just created has a single database
- named Default.
- 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.
-
-
-
- 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 client subdirectory of the YAZ distribution
- and type:
-
-
-
- $ ./yaz-client tcp:localhost:2100
-
-
-
-
- When the client has connected, you can type:
-
-
-
-
-
- Z> find surficial
- Z> show 1
-
-
-
-
- The default retrieval syntax for the client is USMARC. To try other
- formats for the same record, try:
-
-
-
- Z>format sutrs
- Z>show 1
- Z>format grs-1
- Z>show 1
- Z>elements B
- Z>show 1
-
-
-
-
- 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.
-
-
-
- If you've made it this far, there's a good chance that
- you've got through the compilation OK.
-
-
-
-
+
Administrating Zebra
-
+
+
Unlike many simpler retrieval systems, Zebra supports safe, incremental
updates to an existing index.
@@ -141,9 +34,9 @@
Modify
- 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.
+ 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.
@@ -161,8 +54,8 @@
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).
+ indexer must be able to generate a unique key that identifies the record
+ in question (more on this below).
@@ -174,8 +67,9 @@
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 zebra.cfg.
+ set of index files and a global configuration file.
+ The name of the configuration file defaults to
+ zebra.cfg.
The configuration file includes specifications on how to index
various kinds of records and where the other configuration files
are located. zebrasrv and zebraidx
@@ -191,7 +85,7 @@
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:
+ 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 -t or specify a
@@ -211,8 +105,8 @@
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 (#) are
+ parameter names and values are separated by colons in the file. Lines
+ starting with a hash sign (#) are
treated as comments.
@@ -258,13 +152,18 @@
explained further in the following sections.
+
+
group
- .recordType[.name]
+ .recordType[.name]:
+ type
@@ -282,36 +181,42 @@
- group.recordId
+ group.recordId:
+ record-id-spec
Specifies how the records are to be identified when updated. See
- section .
+ .
- group.database
+ group.database:
+ database
Specifies the Z39.50 database name.
+
- group.storeKeys
+ group.storeKeys:
+ boolean
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
- .
+ should be 0 (default), to save register space.
+
+ See .
- group.storeData
+ group.storeData:
+ boolean
Specifies whether the records should be stored internally
@@ -324,28 +229,28 @@
- register
+
+ register: register-location
Specifies the location of the various register files that Zebra uses
- to represent your databases. See section
- .
+ to represent your databases.
+ See .
- shadow
+ shadow: register-location
Enables the safe update facility of Zebra, and
tells the system where to place the required, temporary files.
- See section
- .
+ See .
- lockDir
+ lockDir: directory
Directory in which various lock files are stored.
@@ -353,16 +258,16 @@
- keyTmpDir
+ keyTmpDir: directory
- Directory in which temporary files used during zebraidx' update
+ Directory in which temporary files used during zebraidx's update
phase are stored.
- setTmpDir
+ setTmpDir: directory
Specifies the directory that the server uses for temporary result sets.
@@ -371,15 +276,17 @@
- profilePath
+ profilePath: path
- Specifies the location of profile specification files.
+ Specifies a path of profile specification files.
+ The path is composed of one or more directories separated by
+ colon. Similar to PATH for UNIX systems.
- attset
+ attset: filename
Specifies the filename(s) of attribute set files for use in
@@ -387,19 +294,68 @@
(bib1.att).
The profilePath setting is used to look for
the specified files.
- See section
+ See
+
+
+
+
+ memMax: size
+
+
+ Specifies size 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.
+
+
+
+
+ tempfiles: Yes/Auto/No
+
+
+ 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 memMax
+ megabytes of memory. This should be good for most uses.
+
+
+
+
+
+ root: dir
+
+
+ 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
+ zebra.cfg is located.
+
+
+
@@ -409,14 +365,15 @@
Locating Records
- The default behaviour of the Zebra system is to reference the
+ The default behavior of the Zebra system is to reference the
records from their original location, i.e. where they were found when you
ran zebraidx.
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 zebraidx again, the client
- will receive a diagnostic message.
+ running zebraidx again, the server will return
+ diagnostic number 14 (``System error in presenting records'') to
+ the client.
@@ -461,7 +418,7 @@
- profilePath: /usr/local/yaz
+ profilePath: /usr/local/idzebra/tab
attset: bib1.att
simple.recordType: text
simple.database: textbase
@@ -509,7 +466,7 @@
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 safe update
- facility (see below), you never have to take your server offline for
+ facility (see below), you never have to take your server off-line for
maintenance or register updating purposes.
@@ -519,9 +476,13 @@
in the configuration file. In addition, you should set
storeKeys to 1, 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.
+ in order to modify the indexes correctly at a later time.
+
+
For example, to update records of group esdd
located below
@@ -557,13 +518,14 @@
and then run zebraidx with the
update command.
+
Indexing with General Record IDs
- When using this method you construct an (almost) arbritrary, internal
+ 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
@@ -672,7 +634,7 @@
- (see section
+ (see
for details of how the mapping between elements of your records and
searchable attributes is established).
@@ -726,19 +688,22 @@
each directory in the order specified and use the next specified
directories as needed.
The size is an integer followed by a qualifier
- code, M for megabytes,
+ code,
+ b for bytes,
k for kilobytes.
+ M for megabytes,
+ G for gigabytes.
For instance, if you have allocated two disks for your register, and
the first disk is mounted
- on /d1 and has 200 Mb of free space and the
- second, mounted on /d2 has 300 Mb, you could
+ on /d1 and has 2GB of free space and the
+ second, mounted on /d2 has 3.6 GB, you could
put this entry in your configuration file:
- register: /d1:200M /d2:300M
+ register: /d1:2G /d2:3600M
@@ -749,7 +714,7 @@
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.
+ file system exclusively to the Zebra register files.
@@ -821,7 +786,7 @@
zebra.cfg file.
The syntax of the shadow entry is exactly the
same as for the register entry
- (see section ).
+ (see ).
The location of the shadow area should be
different from the location of the main register
area (if you have specified one - remember that if you provide no
@@ -855,14 +820,13 @@
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:
- $ zebraidx update /d1/records update /d2/more-records commit
+ $ zebraidx update /d1/records
+ $ zebraidx commit
@@ -874,7 +838,7 @@
- $ zebraidx -g books update /d1/records update /d2/more-records
+ $ zebraidx -g books update /d1/records /d2/more-records
$ zebraidx -g fun update /d3/fun-records
$ zebraidx commit
@@ -924,2550 +888,6 @@
-
-
- Running the Maintenance Interface (zebraidx)
-
-
- The following is a complete reference to the command line interface to
- the zebraidx application.
-
-
-
- Syntax
-
-
- $ zebraidx [options] command [directory] ...
-
-
- Options:
-
-
-
- -t type
-
-
- Update all files as type. Currently, the
- types supported are text and
- grs.subtype.
- If no subtype is provided for the GRS
- (General Record Structure) type, the canonical input format
- is assumed (see section ).
- Generally, it is probably advisable to specify the record types
- in the zebra.cfg file (see section
- ), to avoid confusion at
- subsequent updates.
-
-
-
-
- -c config-file
-
-
- Read the configuration file
- config-file instead of
- zebra.cfg.
-
-
-
-
- -g group
-
-
- Update the files according to the group
- settings for group (see section
- ).
-
-
-
-
- -d database
-
-
- The records located should be associated with the database name
- database for access through the Z39.50 server.
-
-
-
-
- -m mbytes
-
-
- Use mbytes of megabytes before flushing
- keys to background storage. This setting affects performance when
- updating large databases.
-
-
-
-
- -n
-
-
- Disable the use of shadow registers for this operation
- (see section ).
-
-
-
-
- -s
-
-
- 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.
-
-
-
-
- -V
-
-
- Show Zebra version.
-
-
-
-
- -v level
-
-
- Set the log level to level.
- level should be one of
- none, debug, and
- all.
-
-
-
-
-
-
-
- Commands
-
-
-
- update directory
-
-
- Update the register with the files contained in
- directory.
- If no directory is provided, a list of files is read from
- stdin.
- See section .
-
-
-
-
- delete directory
-
-
- Remove the records corresponding to the files found under
- directory from the register.
-
-
-
-
- commit
-
-
- Write the changes resulting from the last update
- commands to the register. This command is only available if the use of
- shadow register files is enabled (see section
- ).
-
-
-
-
-
-
-
-
-
- The Z39.50 Server
-
-
- Running the Z39.50 Server (zebrasrv)
-
-
- Syntax
-
-
- zebrasrv [options] [listener-address ...]
-
-
-
-
-
- Options
-
-
-
- -a APDU file
-
-
- Specify a file for dumping PDUs (for diagnostic purposes).
- The special name "-" sends output to stderr.
-
-
-
-
- -c config-file
-
-
- Read configuration information from
- config-file.
- The default configuration is ./zebra.cfg.
-
-
-
-
- -S
-
-
- 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.
-
-
-
-
- -s
-
-
- Use the SR protocol.
-
-
-
-
- -z
-
-
- 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.
-
-
-
-
- -l logfile
-
-
- Specify an output file for the diagnostic messages.
- The default is to write this information to stderr.
-
-
-
-
- -v log-level
-
-
- The log level. Use a comma-separated list of members of the set
- {fatal,debug,warn,log,all,none}.
-
-
-
-
- -u username
-
-
- Set user ID. Sets the real UID of the server process to that of the
- given username.
- 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.
-
-
-
-
- -w working-directory
-
-
- Change working directory.
-
-
-
-
- -i
-
-
- Run under the Internet superserver, inetd.
- Make sure you use the logfile option -l in
- conjunction with this mode and specify the -l
- option before any other options.
-
-
-
-
- -t timeout
-
-
- Set the idle session timeout (default 60 minutes).
-
-
-
-
- -k kilobytes
-
-
- Set the (approximate) maximum size of
- present response messages. Default is 1024 Kb (1 Mb).
-
-
-
-
-
-
-
- A listener-address consists of a transport
- mode followed by a colon (:) followed by a listener address.
- The transport mode is either ssl or
- tcp.
-
-
-
- For TCP, an address has the form
-
-
-
-
-
- hostname | IP-number [: portnumber]
-
-
-
-
-
- The port number defaults to 210 (standard Z39.50 port).
-
-
-
- Examples
-
-
-
-
-
- tcp:dranet.dra.com
-
- ssl:secure.lib.com:3000
-
-
-
-
-
- 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):
-
-
-
-
-
- zebrasrv -u daemon tcp:@
-
-
-
-
-
- You can replace daemon with another user, eg.
- your own account, or a dedicated IR server account.
-
-
-
- The default behavior for zebrasrv is to establish
- a single TCP/IP listener, for the Z39.50 protocol, on port 9999.
-
-
-
-
-
- Z39.50 Protocol Support and Behavior
-
-
- Initialization
-
-
- 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.
-
-
-
-
-
- Search
-
-
- 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.
-
-
-
- The server has full support for piggy-backed present requests (see
- also the following section).
-
-
-
- Use attributes are interpreted according to the
- attribute sets which have been loaded in the
- zebra.cfg file, and are matched against specific
- fields as specified in the .abs 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.
-
-
-
- If a Structure attribute of
- Phrase is used in conjunction with a
- Completeness attribute of
- Complete (Sub)field, the term is matched
- against the contents of the phrase (long word) register, if one
- exists for the given Use attribute.
- A phrase register is created for those fields in the
- .abs file that contains a
- p-specifier.
-
-
-
- If Structure=Phrase is
- used in conjunction with Incomplete Field - the
- default value for Completeness, 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 w in the .abs file.
-
-
-
- If the Structure attribute is
- Word List,
- Free-form Text, or
- Document Text, 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 w in the
- .abs file.
-
-
-
- If the Structure attribute is
- Numeric String the term is treated as an integer.
- The search is performed on those fields that are indexed
- as type n in the .abs file.
-
-
-
- If the Structure attribute is
- URx the term is treated as a URX (URL) entity.
- The search is performed on those fields that are indexed as type
- u in the .abs file.
-
-
-
- If the Structure attribute is
- Local Number the term is treated as
- native Zebra Record Identifier.
-
-
-
- If the Relation attribute is
- Equals (default), the term is matched
- in a normal fashion (modulo truncation and processing of
- individual words, if required).
- If Relation is Less Than,
- Less Than or Equal,
- Greater than, or Greater than or
- Equal, the term is assumed to be numerical, and a
- standard regular expression is constructed to match the given
- expression.
- If Relation is Relevance,
- the standard natural-language query processor is invoked.
-
-
-
- For the Truncation attribute,
- No Truncation is the default.
- Left Truncation is not supported.
- Process # is supported, as is
- Regxp-1.
- Regxp-2 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.
-
-
-
- Regular expressions
-
-
- Each term in a query is interpreted as a regular expression if
- the truncation value is either Regxp-1 (102)
- or Regxp-2 (103).
- Both query types follow the same syntax with the operands:
-
-
-
- x
-
-
- Matches the character x.
-
-
-
-
- .
-
-
- Matches any character.
-
-
-
-
- [..]
-
-
- Matches the set of characters specified;
- such as [abc] or [a-c].
-
-
-
-
- and the operators:
-
-
-
- x*
-
-
- Matches x zero or more times. Priority: high.
-
-
-
-
- x+
-
-
- Matches x one or more times. Priority: high.
-
-
-
-
- x?
-
-
- Matches x once or twice. Priority: high.
-
-
-
-
- xy
-
-
- Matches x, then y.
- Priority: medium.
-
-
-
-
- x|y
-
-
- Matches either x or y.
- Priority: low.
-
-
-
-
- The order of evaluation may be changed by using parentheses.
-
-
-
- If the first character of the Regxp-2 query
- is a plus character (+) 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.
-
-
-
- Since the plus operator is normally a suffix operator the addition to
- the query syntax doesn't violate the syntax for standard regular
- expressions.
-
-
-
-
-
- Query examples
-
-
- Phrase search for information retrieval in
- the title-register:
-
- @attr 1=4 "information retrieval"
-
-
-
-
- Ranked search for the same thing:
-
- @attr 1=4 @attr 2=102 "Information retrieval"
-
-
-
-
- Phrase search with a regular expression:
-
- @attr 1=4 @attr 5=102 "informat.* retrieval"
-
-
-
-
- Ranked search with a regular expression:
-
- @attr 1=4 @attr 5=102 @attr 2=102 "informat.* retrieval"
-
-
-
-
- In the GILS schema (gils.abs), the
- west-bounding-coordinate is indexed as type n,
- and is therefore searched by specifying
- structure=Numeric String.
- To match all those records with west-bounding-coordinate greater
- than -114 we use the following query:
-
- @attr 4=109 @attr 2=5 @attr gils 1=2038 -114
-
-
-
-
-
-
- Present
-
- 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.
-
-
-
- Scan
-
- 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.
-
-
-
- Sort
-
-
- 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.
-
-
-
- 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.
-
-
-
- Close
-
- 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.
-
-
-
-
-
-
- The Record Model
-
-
- 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 record schema 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.
-
-
-
- The record model described in this chapter applies to the fundamental,
- structured
- record type grs as introduced in
- section .
-
-
-
- Records pass through three different states during processing in the
- system.
-
-
-
-
-
-
-
-
- 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:
-
-
-
-
-
-
- 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.),
-
-
-
-
-
-
- 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.
-
-
-
-
-
-
-
-
- Local Representation
-
-
- 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.
-
-
-
- The RecordType parameter in the zebra.cfg file, or
- the -t 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 text 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.
-
-
-
- Three basic subtypes to the grs type are
- currently available:
-
-
-
-
-
- grs.sgml
-
-
- This is the canonical input format —
- described below. It is a simple SGML-like syntax.
-
-
-
-
- grs.regx.filter
-
-
- This enables a user-supplied input
- filter. The mechanisms of these filters are described below.
-
-
-
-
- grs.marc.abstract syntax
-
-
- This allows Zebra to read
- records in the ISO2709 (MARC) encoding standard. In this case, the
- last paramemeter abstract syntax names the
- .abs file (see below)
- which describes the specific MARC structure of the input record as
- well as the indexing rules.
-
-
-
-
-
-
-
- Canonical Input Format
-
-
- 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.
-
-
-
- To use the canonical format specify grs.sgml as
- the record type.
-
-
-
- Consider a record describing an information resource (such a record is
- sometimes known as a locator record).
- 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:
-
-
-
-
-
- <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>
-
-
-
-
-
-
- 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.
-
-
-
- The keywords surrounded by <...> are
- tags, while the sections of text
- in between are the data elements.
- 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 </, and containing the same symbolic
- tag-name as the corresponding opening tag.
- The general closing tag - <>/ -
- terminates the element started by the last opening tag. The
- structuring of elements is significant.
- The element Telephone,
- for instance, may be indexed and presented to the client differently,
- depending on whether it appears inside the
- Distributor element, or some other,
- structured data element such a Supplier element.
-
-
-
- Record Root
-
-
- 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
- ).
- 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):
-
-
-
-
-
- <gils>
- <title>Zen and the Art of Motorcycle Maintenance</title>
- </gils>
-
-
-
-
-
-
-
- Variants
-
-
- Zebra allows you to provide individual data elements in a number of
- variant forms. 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 following is an example of a title element which occurs in two
- different languages.
-
-
-
-
-
- <title>
- <var lang lang "eng">
- Zen and the Art of Motorcycle Maintenance</>
- <var lang lang "dan">
- Zen og Kunsten at Vedligeholde en Motorcykel</>
- </title>
-
-
-
-
-
- The syntax of the variant element is
- <var class type value>.
- The available values for the class and
- type fields are given by the variant set
- that is associated with the current schema
- (see section ).
-
-
-
- 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 class and
- value 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.
-
-
-
- Variant elements can be nested. The element
-
-
-
-
-
- <title>
- <var lang lang "eng"><var body iana "text/plain">
- Zen and the Art of Motorcycle Maintenance
- </title>
-
-
-
-
-
- Associates two variant components to the variant list for the title
- element.
-
-
-
- Given the nesting rules described above, we could write
-
-
-
-
-
- <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>
-
-
-
-
-
- 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.
-
-
-
-
-
-
-
- Input Filters
-
-
- 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.
-
-
-
- Input filters are ASCII files, generally with the suffix
- .flt.
- The system looks for the files in the directories given in the
- profilePath setting in the
- zebra.cfg files.
- The record type for the filter is
- grs.regx.filter-filename
- (fundamental type grs, file read
- type regx, argument
- filter-filename).
-
-
-
- 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.
-
-
-
- An expression can be either of the following:
-
-
-
-
-
-
- INIT
-
-
- 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.
-
-
-
-
- BEGIN
-
-
- Matches the beginning of the record. It can be used to
- initialize variables, etc. Typically, the
- BEGIN rule is also used
- to establish the root node of the record.
-
-
-
-
- END
-
-
- Matches the end of the record - when all of the contents
- of the record has been processed.
-
-
-
-
- /pattern/
-
-
- Matches a string of characters from the input record.
-
-
-
-
- BODY
-
-
- This keyword may only be used between two patterns.
- It matches everything between (not including) those patterns.
-
-
-
-
- FINISH
-
-
- 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
- INIT step.
-
-
-
-
-
-
-
- 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, $2, etc.
-
-
-
- The available statements are:
-
-
-
-
-
-
- begin type [parameter ... ]
-
-
- Begin a new
- data element. The type is one of the following:
-
-
-
- record
-
-
- Begin a new record. The followingparameter should be the
- name of the schema that describes the structure of the record, eg.
- gils or wais (see below).
- The begin record call should precede
- any other use of the begin statement.
-
-
-
-
- element
-
-
- Begin a new tagged element. The parameter is the
- name of the tag. If the tag is not matched anywhere in the tagsets
- referenced by the current schema, it is treated as a local string
- tag.
-
-
-
-
- variant
-
-
- Begin a new node in a variant tree. The parameters are
- class type value.
-
-
-
-
-
-
-
-
- data
-
-
- Create a data element. The concatenated arguments make
- up the value of the data element.
- The option -text signals that
- the layout (whitespace) of the data should be retained for
- transmission.
- The option -element
- tag wraps the data up in
- the tag.
- The use of the -element option is equivalent to
- preceding the command with a begin
- element command, and following
- it with the end command.
-
-
-
-
- end [type]
-
-
- Close a tagged element. If no parameter is given,
- the last element on the stack is terminated.
- The first parameter, if any, is a type name, similar
- to the begin statement.
- For the element type, a tag
- name can be provided to terminate a specific tag.
-
-
-
-
-
-
-
- The following input filter reads a Usenet news file, producing a
- record in the WAIS schema. Note that the body of a news posting is
- separated from the list of headers by a blank line (or rather a
- sequence of two newline characters.
-
-
-
-
-
- BEGIN { begin record wais }
-
- /^From:/ BODY /$/ { 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
- }
-
-
-
-
-
- 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.
-
-
-
- NOTE: Tcl support is not currently available, but will be
- included with one of the next alpha or beta releases.
-
-
-
- NOTE: Variant support is not currently available in the input
- filter, but will be included with one of the next alpha or beta
- releases.
-
-
-
-
-
-
-
- Internal Representation
-
-
- 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:
-
-
-
-
-
- TITLE "Zen and the Art of Motorcycle Maintenance"
- ROOT
- AUTHOR "Robert Pirsig"
-
-
-
-
-
- A slightly more complex record would have the author element consist
- of two elements, a surname and a first name:
-
-
-
-
-
- TITLE "Zen and the Art of Motorcycle Maintenance"
- ROOT
- FIRST-NAME "Robert"
- AUTHOR
- SURNAME "Pirsig"
-
-
-
-
-
- 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.
-
-
-
- Tagged Elements
-
-
- 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).
-
-
-
-
-
- Variants
-
-
- 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 variant form of the
- tagged element identified by the tag which parents the variant tree.
- The following title element occurs in two different languages:
-
-
-
-
-
- VARIANT LANG=ENG "War and Peace"
- TITLE
- VARIANT LANG=DAN "Krig og Fred"
-
-
-
-
-
- Which of the two elements are transmitted to the client by the server
- depends on the specifications provided by the client, if any.
-
-
-
- In practice, each variant node is associated with a triple of class,
- type, value, corresponding to the variant mechanism of Z39.50.
-
-
-
-
-
- Data Elements
-
-
- Data nodes have no children (they are always leaf nodes in the record
- tree).
-
-
-
-
- Documentation needs extension here about types of nodes - numerical,
- textual, etc., plus the various types of inclusion notes.
-
-
-
-
-
-
-
-
- Configuring Your Data Model
-
-
- 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 profilePath
- setting in the zebra.cfg file.
-
-
-
- The Abstract Syntax
-
-
- 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:
-
-
-
-
-
-
-
-
- The object identifier of the Z39.50 schema associated
- with the ARS, so that it can be referred to by the client.
-
-
-
-
-
- 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.
-
-
-
-
-
- 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.
-
-
-
-
-
- The variant set which is used in the profile. This provides a
- vocabulary for specifying the forms of data that appear inside
- the records.
-
-
-
-
-
- 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 element
- specifications, which contain information equivalent to the
- Espec-1 syntax of Z39.50.
-
-
-
-
-
- Map tables, which may specify mappings to
- other database profiles, if desired.
-
-
-
-
-
- Possibly, a set of rules describing the mapping of elements to a
- MARC representation.
-
-
-
-
-
-
- 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.
-
-
-
-
-
-
-
-
- Several of the entries above simply refer to other files, which
- describe the given objects.
-
-
-
-
-
- The Configuration Files
-
-
- This section describes the syntax and use of the various tables which
- are used by the retrieval module.
-
-
-
- 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.
-
-
-
- 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 directives, 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).
-
-
-
-
-
- The Abstract Syntax (.abs) Files
-
-
- 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.
-
-
-
- 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, <gils>, the system will look
- for the profile definition in the file gils.abs.
- Profile definitions are cached, so they only have to be read once
- during the lifespan of the current process.
-
-
-
- When writing your own input filters, the
- record-begin command
- introduces the profile, and should always be called first thing when
- introducing a new record.
-
-
-
- The file may contain the following directives:
-
-
-
-
-
-
- name symbolic-name
-
-
- (m) This provides a shorthand name or
- description for the profile. Mostly useful for diagnostic purposes.
-
-
-
-
- reference OID-name
-
-
- (m) The reference name of the OID for the profile.
- The reference names can be found in the util
- module of YAZ.
-
-
-
-
- attset filename
-
-
- (m) The attribute set that is used for
- indexing and searching records belonging to this profile.
-
-
-
-
- tagset filename
-
-
- (o) The tag set (if any) that describe
- that fields of the records.
-
-
-
-
- varset filename
-
-
- (o) The variant set used in the profile.
-
-
-
-
- maptab filename
-
-
- (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.
-
-
-
- marc filename
-
-
- (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.
-
-
-
- esetname name filename
-
-
- (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.
-
-
-
- any tags
-
-
- (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 elm directive below.
-
-
-
- elm path name attributes
-
-
- (o,r) Adds an element to the abstract record syntax of the schema.
- The path 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 name is the name of the element, and
- the attributes
- 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 field
- types 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 .
- The default field type is "w" for word.
-
-
-
-
-
-
-
- The mechanism for controlling indexing is not adequate for
- complex databases, and will probably be moved into a separate
- configuration table eventually.
-
-
-
-
- The following is an excerpt from the abstract syntax file for the GILS
- profile.
-
-
-
-
-
- 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 !
-
-
-
-
-
-
-
- The Attribute Set (.att) Files
-
-
- This file type describes the Use elements of
- an attribute set.
- It contains the following directives.
-
-
-
-
-
- name symbolic-name
-
-
- (m) This provides a shorthand name or
- description for the attribute set.
- Mostly useful for diagnostic purposes.
-
-
-
- reference OID-name
-
-
- (m) The reference name of the OID for
- the attribute set.
- The reference names can be found in the util
- module of YAZ.
-
-
-
- include filename
-
-
- (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 bib-1 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.
-
-
-
- att
- att-value att-name [local-value]
-
-
- (o,r) This
- repeatable directive introduces a new attribute to the set. The
- attribute value is stored in the index (unless a
- local-value is
- given, in which case this is stored). The name is used to refer to the
- attribute from the abstract syntax.
-
-
-
-
-
-
- This is an excerpt from the GILS attribute set definition.
- Notice how the file describing the bib-1
- attribute set is referenced.
-
-
-
-
-
- name gils
- reference GILS-attset
- include bib1.att
-
- att 2001 distributorName
- att 2002 indextermsControlled
- att 2003 purpose
- att 2004 accessConstraints
- att 2005 useConstraints
-
-
-
-
-
-
-
- The Tag Set (.tag) Files
-
-
- 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.
-
-
-
-
-
-
- name symbolic-name
-
-
- (m) This provides a shorthand name or
- description for the tag set. Mostly useful for diagnostic purposes.
-
-
-
- reference OID-name
-
-
- (o) The reference name of the OID for the tag set.
- The reference names can be found in the util
- module of YAZ.
- The directive is optional, since not all tag sets
- are registered outside of their schema.
-
-
-
- type integer
-
-
- (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).
-
-
-
- include filename
-
-
- (o,r) This directive is used
- to include the definitions of other tag sets into the current one.
-
-
-
- tag number names type
-
-
- (o,r) Introduces a new tag to the set.
- The number 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 names 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 type is th recommended datatype of
- the tag.
- It should be one of the following:
-
-
-
-
- structured
-
-
-
-
-
- string
-
-
-
-
-
- numeric
-
-
-
-
-
- bool
-
-
-
-
-
- oid
-
-
-
-
-
- generalizedtime
-
-
-
-
-
- intunit
-
-
-
-
-
- int
-
-
-
-
-
- octetstring
-
-
-
-
-
- null
-
-
-
-
-
-
-
-
-
-
-
- The following is an excerpt from the TagsetG definition file.
-
-
-
-
- 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
-
-
-
-
-
-
- The Variant Set (.var) Files
-
-
- The variant set file is a straightforward representation of the
- variant set definitions associated with the protocol. At present, only
- the Variant-1 set is known.
-
-
-
- These are the directives allowed in the file.
-
-
-
-
-
-
- name symbolic-name
-
-
- (m) This provides a shorthand name or
- description for the variant set. Mostly useful for diagnostic purposes.
-
-
-
- reference OID-name
-
-
- (o) The reference name of the OID for
- the variant set, if one is required. The reference names can be found
- in the util module of YAZ.
-
-
-
- class integer class-name
-
-
- (m,r) Introduces a new
- class to the variant set.
-
-
-
- type integer type-name datatype
-
-
- (m,r) Addes a
- new type to the current class (the one introduced by the most recent
- class directive).
- The type names belong to the same name space as the one used
- in the tag set definition file.
-
-
-
-
-
-
- The following is an excerpt from the file describing the variant set
- Variant-1.
-
-
-
-
-
- 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
-
-
-
-
-
-
-
- The Element Set (.est) Files
-
-
- 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 Espec-1
- syntax of the Z39.50 specification.
- In fact, the internal representation of an element set
- specification is identical to the Espec-1 structure,
- and we'll refer you to the description of that structure for most of
- the detailed semantics of the directives below.
-
-
-
-
- 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.
-
-
-
-
- The directives available in the element set file are as follows:
-
-
-
-
-
- defaultVariantSetId OID-name
-
-
- (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
- Variant-1 should be given here.
-
-
-
- defaultVariantRequest variant-request
-
-
- (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.
-
-
-
- simpleElement
- path ['variant' variant-request]
-
-
- (o,r) This corresponds to a simple element request
- in Espec-1.
- The path consists of a sequence of tag-selectors, where each of
- these can consist of either:
-
-
-
-
-
-
- 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.
-
-
-
-
-
- A WildThing, represented as a question mark (?), possibly
- followed by a colon (:) followed by an occurrences
- specification (see below).
-
-
-
-
-
- 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).
-
-
-
-
-
-
-
-
- The occurrences-specification can be either the string
- all, the string last, 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).
-
-
-
- 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 Espec-1,
- but it works in this implementation).
-
-
-
-
-
-
- The following is an example of an element specification belonging to
- the GILS profile.
-
-
-
-
-
- simpleelement (1,10)
- simpleelement (1,12)
- simpleelement (2,1)
- simpleelement (1,14)
- simpleelement (4,1)
- simpleelement (4,52)
-
-
-
-
-
-
-
- The Schema Mapping (.map) Files
-
-
- 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.
-
-
-
- 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.
-
-
-
- These are the directives of the schema mapping file format:
-
-
-
-
-
-
- targetName name
-
-
- (m) A symbolic name for the target schema
- of the table. Useful mostly for diagnostic purposes.
-
-
-
- targetRef OID-name
-
-
- (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 oid
- module of YAZ.
-
-
-
- map element-name target-path
-
-
- (o,r) Adds
- an element mapping rule to the table.
-
-
-
-
-
-
-
-
- The MARC (ISO2709) Representation (.mar) Files
-
-
- 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.
-
-
-
- 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.
-
-
-
-
-
- Field Structure and Character Sets
-
-
-
- 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.
-
-
-
- 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).
-
-
-
- The field types, and hence character sets, are associated with data
- elements by the .abs files (see above).
- The file default.idx
- 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
-
-
-
-
-
-
- index field type code
-
-
- 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 .
-
-
-
- sort field code type
-
-
- 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.
-
-
-
- completeness boolean
-
-
- This directive enables or disables complete field indexing.
- The value of the boolean 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.
-
-
-
- charmap filename
-
-
- This is the filename of the character
- map to be used for this index for field type.
-
-
-
-
-
-
- The contents of the character map files are structured as follows:
-
-
-
-
-
-
- lowercase value-set
-
-
- 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:
-
-
-
-
-
-
-
- Backslashes may be used to introduce three-digit octal, or
- two-digit hex representations of single characters
- (preceded by x).
- 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.
-
-
-
-
-
- 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.
-
-
-
-
-
- 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.
-
-
-
-
-
-
-
-
- uppercase value-set
-
-
- 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
- lowercase directive.
-
-
-
- space value-set
-
-
- 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
- uppercase and lowercase
- directives.
-
-
-
- map value-set
- target
-
-
- 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 lowercase 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.
-
-
-
-
-
-
-
-
-
-
- Exchange Formats
-
-
- Converting records from the internal structure to en exchange format
- is largely an automatic process. Currently, the following exchange
- formats are supported:
-
-
-
-
-
-
- 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.
-
-
-
-
-
- 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.
-
-
-
-
-
- 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 ), 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.
-
-
-
-
-
- Explain. This representation is only available for records
- belonging to the Explain schema.
-
-
-
-
-
- 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).
-
-
-
-
-
- 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.
-
-
-
-
-
-
-
-
-
-