1 <chapter id="record-model">
2 <!-- $Id: recordmodel.xml,v 1.20 2005-01-04 19:08:24 quinn Exp $ -->
3 <title>The Record Model</title>
6 The Zebra system is designed to support a wide range of data management
7 applications. The system can be configured to handle virtually any
8 kind of structured data. Each record in the system is associated with
9 a <emphasis>record schema</emphasis> which lends context to the data
10 elements of the record.
11 Any number of record schemas can coexist in the system.
12 Although it may be wise to use only a single schema within
13 one database, the system poses no such restrictions.
17 The record model described in this chapter applies to the fundamental,
19 record type <literal>grs</literal>, introduced in
20 <xref linkend="record-types"/>.
22 FIXME - Need to describe the simple string-tag model, or at least
28 Records pass through three different states during processing in the
38 When records are accessed by the system, they are represented
39 in their local, or native format. This might be SGML or HTML files,
40 News or Mail archives, MARC records. If the system doesn't already
41 know how to read the type of data you need to store, you can set up an
42 input filter by preparing conversion rules based on regular
43 expressions and possibly augmented by a flexible scripting language
45 The input filter produces as output an internal representation,
53 When records are processed by the system, they are represented
54 in a tree-structure, constructed by tagged data elements hanging off a
55 root node. The tagged elements may contain data or yet more tagged
56 elements in a recursive structure. The system performs various
57 actions on this tree structure (indexing, element selection, schema
65 Before transmitting records to the client, they are first
66 converted from the internal structure to a form suitable for exchange
67 over the network - according to the Z39.50 standard.
75 <sect1 id="local-representation">
76 <title>Local Representation</title>
79 As mentioned earlier, Zebra places few restrictions on the type of
80 data that you can index and manage. Generally, whatever the form of
81 the data, it is parsed by an input filter specific to that format, and
82 turned into an internal structure that Zebra knows how to handle. This
83 process takes place whenever the record is accessed - for indexing and
88 The RecordType parameter in the <literal>zebra.cfg</literal> file, or
89 the <literal>-t</literal> option to the indexer tells Zebra how to
90 process input records.
91 Two basic types of processing are available - raw text and structured
92 data. Raw text is just that, and it is selected by providing the
93 argument <emphasis>text</emphasis> to Zebra. Structured records are
94 all handled internally using the basic mechanisms described in the
96 Zebra can read structured records in many different formats.
97 How this is done is governed by additional parameters after the
98 "grs" keyword, separated by "." characters.
102 Four basic subtypes to the <emphasis>grs</emphasis> type are
109 <term>grs.sgml</term>
112 This is the canonical input format —
113 described below. It is a simple SGML-like syntax.
118 <term>grs.regx.<emphasis>filter</emphasis></term>
121 This enables a user-supplied input
122 filter. The mechanisms of these filters are described below.
127 <term>grs.tcl.<emphasis>filter</emphasis></term>
130 Similar to grs.regx but using Tcl for rules.
135 <term>grs.marc.<emphasis>abstract syntax</emphasis></term>
138 This allows Zebra to read
139 records in the ISO2709 (MARC) encoding standard. In this case, the
140 last parameter <emphasis>abstract syntax</emphasis> names the
141 <literal>.abs</literal> file (see below)
142 which describes the specific MARC structure of the input record as
143 well as the indexing rules.
151 This filter reads XML records. Only one record per file
152 is supported. The filter is only available if Zebra/YAZ
153 is compiled with EXPAT support.
162 <title>Canonical Input Format</title>
165 Although input data can take any form, it is sometimes useful to
166 describe the record processing capabilities of the system in terms of
167 a single, canonical input format that gives access to the full
168 spectrum of structure and flexibility in the system. In Zebra, this
169 canonical format is an "SGML-like" syntax.
173 To use the canonical format specify <literal>grs.sgml</literal> as
178 Consider a record describing an information resource (such a record is
179 sometimes known as a <emphasis>locator record</emphasis>).
180 It might contain a field describing the distributor of the
181 information resource, which might in turn be partitioned into
182 various fields providing details about the distributor, like this:
188 <Distributor>
189 <Name> USGS/WRD </Name>
190 <Organization> USGS/WRD </Organization>
191 <Street-Address>
192 U.S. GEOLOGICAL SURVEY, 505 MARQUETTE, NW
193 </Street-Address>
194 <City> ALBUQUERQUE </City>
195 <State> NM </State>
196 <Zip-Code> 87102 </Zip-Code>
197 <Country> USA </Country>
198 <Telephone> (505) 766-5560 </Telephone>
199 </Distributor>
204 <!-- There is no indentation in the example above! -H
207 The indentation used above is used to illustrate how Zebra
208 interprets the mark-up. The indentation, in itself, has no
209 significance to the parser for the canonical input format, which
210 discards superfluous whitespace.
216 The keywords surrounded by <...> are
217 <emphasis>tags</emphasis>, while the sections of text
218 in between are the <emphasis>data elements</emphasis>.
219 A data element is characterized by its location in the tree
220 that is made up by the nested elements.
221 Each element is terminated by a closing tag - beginning
222 with <literal><</literal>/, and containing the same symbolic
223 tag-name as the corresponding opening tag.
224 The general closing tag - <literal></></literal> -
225 terminates the element started by the last opening tag. The
226 structuring of elements is significant.
227 The element <emphasis>Telephone</emphasis>,
228 for instance, may be indexed and presented to the client differently,
229 depending on whether it appears inside the
230 <emphasis>Distributor</emphasis> element, or some other,
231 structured data element such a <emphasis>Supplier</emphasis> element.
235 <title>Record Root</title>
238 The first tag in a record describes the root node of the tree that
239 makes up the total record. In the canonical input format, the root tag
240 should contain the name of the schema that lends context to the
241 elements of the record
242 (see <xref linkend="internal-representation"/>).
243 The following is a GILS record that
244 contains only a single element (strictly speaking, that makes it an
245 illegal GILS record, since the GILS profile includes several mandatory
246 elements - Zebra does not validate the contents of a record against
247 the Z39.50 profile, however - it merely attempts to match up elements
248 of a local representation with the given schema):
255 <title>Zen and the Art of Motorcycle Maintenance</title>
263 <sect3><!-- ### we shouldn't make such a big deal about this -->
264 <title>Variants</title>
267 Zebra allows you to provide individual data elements in a number of
268 <emphasis>variant forms</emphasis>. Examples of variant forms are
269 textual data elements which might appear in different languages, and
270 images which may appear in different formats or layouts.
271 The variant system in Zebra is essentially a representation of
272 the variant mechanism of Z39.50-1995.
276 The following is an example of a title element which occurs in two
284 <var lang lang "eng">
285 Zen and the Art of Motorcycle Maintenance</>
286 <var lang lang "dan">
287 Zen og Kunsten at Vedligeholde en Motorcykel</>
294 The syntax of the <emphasis>variant element</emphasis> is
295 <literal><var class type value></literal>.
296 The available values for the <emphasis>class</emphasis> and
297 <emphasis>type</emphasis> fields are given by the variant set
298 that is associated with the current schema
299 (see <xref linkend="variant-set"/>).
303 Variant elements are terminated by the general end-tag </>, by
304 the variant end-tag </var>, by the appearance of another variant
305 tag with the same <emphasis>class</emphasis> and
306 <emphasis>value</emphasis> settings, or by the
307 appearance of another, normal tag. In other words, the end-tags for
308 the variants used in the example above could have been omitted.
312 Variant elements can be nested. The element
319 <var lang lang "eng"><var body iana "text/plain">
320 Zen and the Art of Motorcycle Maintenance
327 Associates two variant components to the variant list for the title
332 Given the nesting rules described above, we could write
339 <var body iana "text/plain>
340 <var lang lang "eng">
341 Zen and the Art of Motorcycle Maintenance
342 <var lang lang "dan">
343 Zen og Kunsten at Vedligeholde en Motorcykel
350 The title element above comes in two variants. Both have the IANA body
351 type "text/plain", but one is in English, and the other in
352 Danish. The client, using the element selection mechanism of Z39.50,
353 can retrieve information about the available variant forms of data
354 elements, or it can select specific variants based on the requirements
363 <title>Input Filters</title>
366 In order to handle general input formats, Zebra allows the
367 operator to define filters which read individual records in their
368 native format and produce an internal representation that the system
373 Input filters are ASCII files, generally with the suffix
374 <literal>.flt</literal>.
375 The system looks for the files in the directories given in the
376 <emphasis>profilePath</emphasis> setting in the
377 <literal>zebra.cfg</literal> files.
378 The record type for the filter is
379 <literal>grs.regx.</literal><emphasis>filter-filename</emphasis>
380 (fundamental type <literal>grs</literal>, file read
381 type <literal>regx</literal>, argument
382 <emphasis>filter-filename</emphasis>).
386 Generally, an input filter consists of a sequence of rules, where each
387 rule consists of a sequence of expressions, followed by an action. The
388 expressions are evaluated against the contents of the input record,
389 and the actions normally contribute to the generation of an internal
390 representation of the record.
394 An expression can be either of the following:
404 The action associated with this expression is evaluated
405 exactly once in the lifetime of the application, before any records
406 are read. It can be used in conjunction with an action that
407 initializes tables or other resources that are used in the processing
416 Matches the beginning of the record. It can be used to
417 initialize variables, etc. Typically, the
418 <emphasis>BEGIN</emphasis> rule is also used
419 to establish the root node of the record.
427 Matches the end of the record - when all of the contents
428 of the record has been processed.
433 <term>/pattern/</term>
436 Matches a string of characters from the input record.
444 This keyword may only be used between two patterns.
445 It matches everything between (not including) those patterns.
453 The expression associated with this pattern is evaluated
454 once, before the application terminates. It can be used to release
455 system resources - typically ones allocated in the
456 <emphasis>INIT</emphasis> step.
464 An action is surrounded by curly braces ({...}), and
465 consists of a sequence of statements. Statements may be separated
466 by newlines or semicolons (;).
467 Within actions, the strings that matched the expressions
468 immediately preceding the action can be referred to as
473 The available statements are:
480 <term>begin <replaceable>type [parameter ... ]</replaceable></term>
484 data element. The <replaceable>type</replaceable> is one of
492 Begin a new record. The following parameter should be the
493 name of the schema that describes the structure of the record, eg.
494 <literal>gils</literal> or <literal>wais</literal> (see below).
495 The <literal>begin record</literal> call should precede
496 any other use of the <replaceable>begin</replaceable> statement.
504 Begin a new tagged element. The parameter is the
505 name of the tag. If the tag is not matched anywhere in the tagsets
506 referenced by the current schema, it is treated as a local string
515 Begin a new node in a variant tree. The parameters are
516 <replaceable>class type value</replaceable>.
525 <term>data <replaceable>parameter</replaceable></term>
528 Create a data element. The concatenated arguments make
529 up the value of the data element.
530 The option <literal>-text</literal> signals that
531 the layout (whitespace) of the data should be retained for
533 The option <literal>-element</literal>
534 <replaceable>tag</replaceable> wraps the data up in
535 the <replaceable>tag</replaceable>.
536 The use of the <literal>-element</literal> option is equivalent to
537 preceding the command with a <replaceable>begin
538 element</replaceable> command, and following
539 it with the <replaceable>end</replaceable> command.
544 <term>end <replaceable>[type]</replaceable></term>
547 Close a tagged element. If no parameter is given,
548 the last element on the stack is terminated.
549 The first parameter, if any, is a type name, similar
550 to the <replaceable>begin</replaceable> statement.
551 For the <replaceable>element</replaceable> type, a tag
552 name can be provided to terminate a specific tag.
558 <term>unread <replaceable>no</replaceable></term>
561 Move the input pointer to the offset of first character that
562 match rule given by <replaceable>no</replaceable>.
563 The first rule from left-to-right is numbered zero,
564 the second rule is named 1 and so on.
573 The following input filter reads a Usenet news file, producing a
574 record in the WAIS schema. Note that the body of a news posting is
575 separated from the list of headers by a blank line (or rather a
576 sequence of two newline characters.
582 BEGIN { begin record wais }
584 /^From:/ BODY /$/ { data -element name $1 }
585 /^Subject:/ BODY /$/ { data -element title $1 }
586 /^Date:/ BODY /$/ { data -element lastModified $1 }
588 begin element bodyOfDisplay
589 begin variant body iana "text/plain"
598 If Zebra is compiled with support for Tcl enabled, the statements
599 described above are supplemented with a complete
600 scripting environment, including control structures (conditional
601 expressions and loop constructs), and powerful string manipulation
602 mechanisms for modifying the elements of a record.
609 <sect1 id="internal-representation">
610 <title>Internal Representation</title>
613 When records are manipulated by the system, they're represented in a
614 tree-structure, with data elements at the leaf nodes, and tags or
615 variant components at the non-leaf nodes. The root-node identifies the
616 schema that lends context to the tagging and structuring of the
617 record. Imagine a simple record, consisting of a 'title' element and
625 TITLE "Zen and the Art of Motorcycle Maintenance"
626 AUTHOR "Robert Pirsig"
632 A slightly more complex record would have the author element consist
633 of two elements, a surname and a first name:
640 TITLE "Zen and the Art of Motorcycle Maintenance"
649 The root of the record will refer to the record schema that describes
650 the structuring of this particular record. The schema defines the
651 element tags (TITLE, FIRST-NAME, etc.) that may occur in the record, as
652 well as the structuring (SURNAME should appear below AUTHOR, etc.). In
653 addition, the schema establishes element set names that are used by
654 the client to request a subset of the elements of a given record. The
655 schema may also establish rules for converting the record to a
656 different schema, by stating, for each element, a mapping to a
661 <title>Tagged Elements</title>
664 A data element is characterized by its tag, and its position in the
665 structure of the record. For instance, while the tag "telephone
666 number" may be used different places in a record, we may need to
667 distinguish between these occurrences, both for searching and
668 presentation purposes. For instance, while the phone numbers for the
669 "customer" and the "service provider" are both
670 representatives for the same type of resource (a telephone number), it
671 is essential that they be kept separate. The record schema provides
672 the structure of the record, and names each data element (defined by
673 the sequence of tags - the tag path - by which the element can be
674 reached from the root of the record).
680 <title>Variants</title>
683 The children of a tag node may be either more tag nodes, a data node
684 (possibly accompanied by tag nodes),
685 or a tree of variant nodes. The children of variant nodes are either
686 more variant nodes or a data node (possibly accompanied by more
687 variant nodes). Each leaf node, which is normally a
688 data node, corresponds to a <emphasis>variant form</emphasis> of the
689 tagged element identified by the tag which parents the variant tree.
690 The following title element occurs in two different languages:
696 VARIANT LANG=ENG "War and Peace"
698 VARIANT LANG=DAN "Krig og Fred"
704 Which of the two elements are transmitted to the client by the server
705 depends on the specifications provided by the client, if any.
709 In practice, each variant node is associated with a triple of class,
710 type, value, corresponding to the variant mechanism of Z39.50.
716 <title>Data Elements</title>
719 Data nodes have no children (they are always leaf nodes in the record
724 FIXME! Documentation needs extension here about types of nodes - numerical,
725 textual, etc., plus the various types of inclusion notes.
733 <sect1 id="data-model">
734 <title>Configuring Your Data Model</title>
737 The following sections describe the configuration files that govern
738 the internal management of data records. The system searches for the files
739 in the directories specified by the <emphasis>profilePath</emphasis>
740 setting in the <literal>zebra.cfg</literal> file.
744 <title>The Abstract Syntax</title>
747 The abstract syntax definition (also known as an Abstract Record
748 Structure, or ARS) is the focal point of the
749 record schema description. For a given schema, the ABS file may state any
750 or all of the following:
754 FIXME - Need a diagram here, or a simple explanation how it all hangs together -H
763 The object identifier of the Z39.50 schema associated
764 with the ARS, so that it can be referred to by the client.
770 The attribute set (which can possibly be a compound of multiple
771 sets) which applies in the profile. This is used when indexing and
772 searching the records belonging to the given profile.
778 The tag set (again, this can consist of several different sets).
779 This is used when reading the records from a file, to recognize the
780 different tags, and when transmitting the record to the client -
781 mapping the tags to their numerical representation, if they are
788 The variant set which is used in the profile. This provides a
789 vocabulary for specifying the <emphasis>forms</emphasis> of
790 data that appear inside the records.
796 Element set names, which are a shorthand way for the client to
797 ask for a subset of the data elements contained in a record. Element
798 set names, in the retrieval module, are mapped to <emphasis>element
799 specifications</emphasis>, which contain information equivalent to the
800 <emphasis>Espec-1</emphasis> syntax of Z39.50.
806 Map tables, which may specify mappings to
807 <emphasis>other</emphasis> database profiles, if desired.
813 Possibly, a set of rules describing the mapping of elements to a
821 A list of element descriptions (this is the actual ARS of the
822 schema, in Z39.50 terms), which lists the ways in which the various
823 tags can be used and organized hierarchically.
832 Several of the entries above simply refer to other files, which
833 describe the given objects.
839 <title>The Configuration Files</title>
842 This section describes the syntax and use of the various tables which
843 are used by the retrieval module.
847 The number of different file types may appear daunting at first, but
848 each type corresponds fairly clearly to a single aspect of the Z39.50
849 retrieval facilities. Further, the average database administrator,
850 who is simply reusing an existing profile for which tables already
851 exist, shouldn't have to worry too much about the contents of these tables.
855 Generally, the files are simple ASCII files, which can be maintained
856 using any text editor. Blank lines, and lines beginning with a (#) are
857 ignored. Any characters on a line followed by a (#) are also ignored.
858 All other lines contain <emphasis>directives</emphasis>, which provide
859 some setting or value to the system.
860 Generally, settings are characterized by a single
861 keyword, identifying the setting, followed by a number of parameters.
862 Some settings are repeatable (r), while others may occur only once in a
863 file. Some settings are optional (o), while others again are
869 <sect2 id="abs-file">
870 <title>The Abstract Syntax (.abs) Files</title>
873 The name of this file type is slightly misleading in Z39.50 terms,
874 since, apart from the actual abstract syntax of the profile, it also
875 includes most of the other definitions that go into a database
880 When a record in the canonical, SGML-like format is read from a file
881 or from the database, the first tag of the file should reference the
882 profile that governs the layout of the record. If the first tag of the
883 record is, say, <literal><gils></literal>, the system will look
884 for the profile definition in the file <literal>gils.abs</literal>.
885 Profile definitions are cached, so they only have to be read once
886 during the lifespan of the current process.
890 When writing your own input filters, the
891 <emphasis>record-begin</emphasis> command
892 introduces the profile, and should always be called first thing when
893 introducing a new record.
897 The file may contain the following directives:
904 <term>name <replaceable>symbolic-name</replaceable></term>
907 (m) This provides a shorthand name or
908 description for the profile. Mostly useful for diagnostic purposes.
913 <term>reference <replaceable>OID-name</replaceable></term>
916 (m) The reference name of the OID for the profile.
917 The reference names can be found in the <emphasis>util</emphasis>
923 <term>attset <replaceable>filename</replaceable></term>
926 (m) The attribute set that is used for
927 indexing and searching records belonging to this profile.
932 <term>tagset <replaceable>filename</replaceable></term>
935 (o) The tag set (if any) that describe
936 that fields of the records.
941 <term>varset <replaceable>filename</replaceable></term>
944 (o) The variant set used in the profile.
949 <term>maptab <replaceable>filename</replaceable></term>
952 (o,r) This points to a
953 conversion table that might be used if the client asks for the record
954 in a different schema from the native one.
959 <term>marc <replaceable>filename</replaceable></term>
962 (o) Points to a file containing parameters
963 for representing the record contents in the ISO2709 syntax.
964 Read the description of the MARC representation facility below.
969 <term>esetname <replaceable>name filename</replaceable></term>
973 given element set name with an element selection file. If an (@) is
974 given in place of the filename, this corresponds to a null mapping for
975 the given element set name.
980 <term>any <replaceable>tags</replaceable></term>
983 (o) This directive specifies a list of attributes
984 which should be appended to the attribute list given for each
985 element. The effect is to make every single element in the abstract
986 syntax searchable by way of the given attributes. This directive
987 provides an efficient way of supporting free-text searching across all
988 elements. However, it does increase the size of the index
989 significantly. The attributes can be qualified with a structure, as in
990 the <replaceable>elm</replaceable> directive below.
995 <term>elm <replaceable>path name attributes</replaceable></term>
998 (o,r) Adds an element to the abstract record syntax of the schema.
999 The <replaceable>path</replaceable> follows the
1000 syntax which is suggested by the Z39.50 document - that is, a sequence
1001 of tags separated by slashes (/). Each tag is given as a
1002 comma-separated pair of tag type and -value surrounded by parenthesis.
1003 The <replaceable>name</replaceable> is the name of the element, and
1004 the <replaceable>attributes</replaceable>
1005 specifies which attributes to use when indexing the element in a
1006 comma-separated list.
1007 A ! in place of the attribute name is equivalent to
1008 specifying an attribute name identical to the element name.
1009 A - in place of the attribute name
1010 specifies that no indexing is to take place for the given element.
1011 The attributes can be qualified with <replaceable>field
1012 types</replaceable> to specify which
1013 character set should govern the indexing procedure for that field.
1014 The same data element may be indexed into several different
1015 fields, using different character set definitions.
1016 See the <xref linkend="field-structure-and-character-sets"/>.
1017 The default field type is <literal>w</literal> for
1018 <emphasis>word</emphasis>.
1024 <term>xelm <replaceable>xpath attributes</replaceable></term>
1027 Specifies indexing for record nodes given by
1028 <replaceable>xpath</replaceable>. Unlike directive
1029 elm, this directive allows you to index attribute
1030 contents. The <replaceable>xpath</replaceable> uses
1031 a syntax similar to XPath. The <replaceable>attributes</replaceable>
1032 have same syntax and meaning as directive elm, except that operator
1033 ! refers to the nodes selected by <replaceable>xpath</replaceable>.
1035 xelm / !:w default index
1036 xelm // !:w additional index
1037 xelm /gils/title/@att myatt:w index attribute @att in myatt
1038 xelm title/@att myatt:w same meaning.
1044 <term>melm <replaceable>field$subfield</replaceable></term>
1047 This directive is specifically for MARC-formatted records,
1048 ingested either in the form of MARCXML documents, or in the
1049 ISO2709/Z39.2 format using the grs.marcxml input filter. You can
1050 specify indexing rules for any subfield, or you can leave off the
1051 <replaceable>$subfield</replaceable> part and specify default rules
1052 for all subfields of the given field (note: default rules should come
1053 after any subfield-specific rules in the configuration file).
1058 <term>encoding <replaceable>encodingname</replaceable></term>
1061 This directive specifies character encoding for external records.
1062 For records such as XML that specifies encoding within the
1063 file via a header this directive is ignored.
1064 If neither this directive is given, nor an encoding is set
1065 within external records, ISO-8859-1 encoding is assumed.
1070 <term>xpath <literal>enable</literal>/<literal>disable</literal></term>
1073 If this directive is followed by <literal>enable</literal>,
1074 then extra indexing is performed to allow for XPath-like queries.
1075 If this directive is not specified - equivalent to
1076 <literal>disable</literal> - no extra XPath-indexing is performed.
1083 <term>systag <replaceable>systemtag</replaceable> <replaceable>element</replaceable></term>
1086 This directive maps system information to an element during
1087 retrieval. This information is dynamically created. The
1088 following system tags are defined
1094 Size of record in bytes. By default this
1095 is mapped to element <literal>size</literal>.
1104 Score/rank of record. By default this
1105 is mapped to element <literal>rank</literal>.
1106 If no score was calculated for the record (non-ranked
1107 searched) search this directive is ignored.
1116 Zebra's system number (record ID) for the
1117 record. By default this is mapped to element
1118 <literal>localControlNumber</literal>.
1123 If you do not want a particular system tag to be applied,
1124 then set the resulting element to something undefined in the
1125 abs file (such as <literal>none</literal>).
1131 <!-- Mike's version -->
1135 <replaceable>systemTag</replaceable>
1136 <replaceable>actualTag</replaceable>
1140 Specifies what information, if any, Zebra should
1141 automatically include in retrieval records for the
1142 ``system fields'' that it supports.
1143 <replaceable>systemTag</replaceable> may
1144 be any of the following:
1147 <term><literal>rank</literal></term>
1149 An integer indicating the relevance-ranking score
1150 assigned to the record.
1154 <term><literal>sysno</literal></term>
1156 An automatically generated identifier for the record,
1157 unique within this database. It is represented by the
1158 <literal><localControlNumber></literal> element in
1159 XML and the <literal>(1,14)</literal> tag in GRS-1.
1163 <term><literal>size</literal></term>
1165 The size, in bytes, of the retrieved record.
1171 The <replaceable>actualTag</replaceable> parameter may be
1172 <literal>none</literal> to indicate that the named element
1173 should be omitted from retrieval records.
1182 The mechanism for controlling indexing is not adequate for
1183 complex databases, and will probably be moved into a separate
1184 configuration table eventually.
1189 The following is an excerpt from the abstract syntax file for the GILS
1197 reference GILS-schema
1202 maptab gils-usmarc.map
1206 esetname VARIANT gils-variant.est # for WAIS-compliance
1207 esetname B gils-b.est
1208 esetname G gils-g.est
1213 elm (1,14) localControlNumber Local-number
1214 elm (1,16) dateOfLastModification Date/time-last-modified
1215 elm (2,1) title w:!,p:!
1216 elm (4,1) controlIdentifier Identifier-standard
1217 elm (2,6) abstract Abstract
1218 elm (4,51) purpose !
1219 elm (4,52) originator -
1220 elm (4,53) accessConstraints !
1221 elm (4,54) useConstraints !
1222 elm (4,70) availability -
1223 elm (4,70)/(4,90) distributor -
1224 elm (4,70)/(4,90)/(2,7) distributorName !
1225 elm (4,70)/(4,90)/(2,10) distributorOrganization !
1226 elm (4,70)/(4,90)/(4,2) distributorStreetAddress !
1227 elm (4,70)/(4,90)/(4,3) distributorCity !
1234 <sect2 id="attset-files">
1235 <title>The Attribute Set (.att) Files</title>
1238 This file type describes the <replaceable>Use</replaceable> elements of
1240 It contains the following directives.
1246 <term>name <replaceable>symbolic-name</replaceable></term>
1249 (m) This provides a shorthand name or
1250 description for the attribute set.
1251 Mostly useful for diagnostic purposes.
1253 </listitem></varlistentry>
1255 <term>reference <replaceable>OID-name</replaceable></term>
1258 (m) The reference name of the OID for
1260 The reference names can be found in the <replaceable>util</replaceable>
1261 module of <replaceable>YAZ</replaceable>.
1263 </listitem></varlistentry>
1265 <term>include <replaceable>filename</replaceable></term>
1268 (o,r) This directive is used to
1269 include another attribute set as a part of the current one. This is
1270 used when a new attribute set is defined as an extension to another
1271 set. For instance, many new attribute sets are defined as extensions
1272 to the <replaceable>bib-1</replaceable> set.
1273 This is an important feature of the retrieval
1274 system of Z39.50, as it ensures the highest possible level of
1275 interoperability, as those access points of your database which are
1276 derived from the external set (say, bib-1) can be used even by clients
1277 who are unaware of the new set.
1279 </listitem></varlistentry>
1282 <replaceable>att-value att-name [local-value]</replaceable></term>
1286 repeatable directive introduces a new attribute to the set. The
1287 attribute value is stored in the index (unless a
1288 <replaceable>local-value</replaceable> is
1289 given, in which case this is stored). The name is used to refer to the
1290 attribute from the <replaceable>abstract syntax</replaceable>.
1292 </listitem></varlistentry>
1297 This is an excerpt from the GILS attribute set definition.
1298 Notice how the file describing the <emphasis>bib-1</emphasis>
1299 attribute set is referenced.
1306 reference GILS-attset
1309 att 2001 distributorName
1310 att 2002 indextermsControlled
1312 att 2004 accessConstraints
1313 att 2005 useConstraints
1321 <title>The Tag Set (.tag) Files</title>
1324 This file type defines the tagset of the profile, possibly by
1325 referencing other tag sets (most tag sets, for instance, will include
1326 tagsetG and tagsetM from the Z39.50 specification. The file may
1327 contain the following directives.
1334 <term>name <emphasis>symbolic-name</emphasis></term>
1337 (m) This provides a shorthand name or
1338 description for the tag set. Mostly useful for diagnostic purposes.
1340 </listitem></varlistentry>
1342 <term>reference <emphasis>OID-name</emphasis></term>
1345 (o) The reference name of the OID for the tag set.
1346 The reference names can be found in the <emphasis>util</emphasis>
1347 module of <emphasis>YAZ</emphasis>.
1348 The directive is optional, since not all tag sets
1349 are registered outside of their schema.
1351 </listitem></varlistentry>
1353 <term>type <emphasis>integer</emphasis></term>
1356 (m) The type number of the tagset within the schema
1357 profile (note: this specification really should belong to the .abs
1358 file. This will be fixed in a future release).
1360 </listitem></varlistentry>
1362 <term>include <emphasis>filename</emphasis></term>
1365 (o,r) This directive is used
1366 to include the definitions of other tag sets into the current one.
1368 </listitem></varlistentry>
1370 <term>tag <emphasis>number names type</emphasis></term>
1373 (o,r) Introduces a new tag to the set.
1374 The <emphasis>number</emphasis> is the tag number as used
1375 in the protocol (there is currently no mechanism for
1376 specifying string tags at this point, but this would be quick
1378 The <emphasis>names</emphasis> parameter is a list of names
1379 by which the tag should be recognized in the input file format.
1380 The names should be separated by slashes (/).
1381 The <emphasis>type</emphasis> is the recommended data type of
1383 It should be one of the following:
1449 </listitem></varlistentry>
1454 The following is an excerpt from the TagsetG definition file.
1465 tag 3 publicationPlace string
1466 tag 4 publicationDate string
1467 tag 5 documentId string
1468 tag 6 abstract string
1470 tag 8 date generalizedtime
1471 tag 9 bodyOfDisplay string
1472 tag 10 organization string
1478 <sect2 id="variant-set">
1479 <title>The Variant Set (.var) Files</title>
1482 The variant set file is a straightforward representation of the
1483 variant set definitions associated with the protocol. At present, only
1484 the <emphasis>Variant-1</emphasis> set is known.
1488 These are the directives allowed in the file.
1495 <term>name <emphasis>symbolic-name</emphasis></term>
1498 (m) This provides a shorthand name or
1499 description for the variant set. Mostly useful for diagnostic purposes.
1501 </listitem></varlistentry>
1503 <term>reference <emphasis>OID-name</emphasis></term>
1506 (o) The reference name of the OID for
1507 the variant set, if one is required. The reference names can be found
1508 in the <emphasis>util</emphasis> module of <emphasis>YAZ</emphasis>.
1510 </listitem></varlistentry>
1512 <term>class <emphasis>integer class-name</emphasis></term>
1515 (m,r) Introduces a new
1516 class to the variant set.
1518 </listitem></varlistentry>
1520 <term>type <emphasis>integer type-name datatype</emphasis></term>
1524 new type to the current class (the one introduced by the most recent
1525 <emphasis>class</emphasis> directive).
1526 The type names belong to the same name space as the one used
1527 in the tag set definition file.
1529 </listitem></varlistentry>
1534 The following is an excerpt from the file describing the variant set
1535 <emphasis>Variant-1</emphasis>.
1546 type 1 variantId octetstring
1551 type 2 z39.50 string
1560 <title>The Element Set (.est) Files</title>
1563 The element set specification files describe a selection of a subset
1564 of the elements of a database record. The element selection mechanism
1565 is equivalent to the one supplied by the <emphasis>Espec-1</emphasis>
1566 syntax of the Z39.50 specification.
1567 In fact, the internal representation of an element set
1568 specification is identical to the <emphasis>Espec-1</emphasis> structure,
1569 and we'll refer you to the description of that structure for most of
1570 the detailed semantics of the directives below.
1575 Not all of the Espec-1 functionality has been implemented yet.
1576 The fields that are mentioned below all work as expected, unless
1582 The directives available in the element set file are as follows:
1588 <term>defaultVariantSetId <emphasis>OID-name</emphasis></term>
1591 (o) If variants are used in
1592 the following, this should provide the name of the variantset used
1593 (it's not currently possible to specify a different set in the
1594 individual variant request). In almost all cases (certainly all
1595 profiles known to us), the name
1596 <literal>Variant-1</literal> should be given here.
1598 </listitem></varlistentry>
1600 <term>defaultVariantRequest <emphasis>variant-request</emphasis></term>
1604 provides a default variant request for
1605 use when the individual element requests (see below) do not contain a
1606 variant request. Variant requests consist of a blank-separated list of
1607 variant components. A variant compont is a comma-separated,
1608 parenthesized triple of variant class, type, and value (the two former
1609 values being represented as integers). The value can currently only be
1610 entered as a string (this will change to depend on the definition of
1611 the variant in question). The special value (@) is interpreted as a
1612 null value, however.
1614 </listitem></varlistentry>
1617 <emphasis>path ['variant' variant-request]</emphasis></term>
1620 (o,r) This corresponds to a simple element request
1621 in <emphasis>Espec-1</emphasis>.
1622 The path consists of a sequence of tag-selectors, where each of
1623 these can consist of either:
1630 A simple tag, consisting of a comma-separated type-value pair in
1631 parenthesis, possibly followed by a colon (:) followed by an
1632 occurrences-specification (see below). The tag-value can be a number
1633 or a string. If the first character is an apostrophe ('), this
1634 forces the value to be interpreted as a string, even if it
1635 appears to be numerical.
1641 A WildThing, represented as a question mark (?), possibly
1642 followed by a colon (:) followed by an occurrences
1643 specification (see below).
1649 A WildPath, represented as an asterisk (*). Note that the last
1650 element of the path should not be a wildPath (wildpaths don't
1651 work in this version).
1660 The occurrences-specification can be either the string
1661 <literal>all</literal>, the string <literal>last</literal>, or
1662 an explicit value-range. The value-range is represented as
1663 an integer (the starting point), possibly followed by a
1664 plus (+) and a second integer (the number of elements, default
1669 The variant-request has the same syntax as the defaultVariantRequest
1670 above. Note that it may sometimes be useful to give an empty variant
1671 request, simply to disable the default for a specific set of fields
1672 (we aren't certain if this is proper <emphasis>Espec-1</emphasis>,
1673 but it works in this implementation).
1675 </listitem></varlistentry>
1680 The following is an example of an element specification belonging to
1687 simpleelement (1,10)
1688 simpleelement (1,12)
1690 simpleelement (1,14)
1692 simpleelement (4,52)
1699 <sect2 id="schema-mapping">
1700 <title>The Schema Mapping (.map) Files</title>
1703 Sometimes, the client might want to receive a database record in
1704 a schema that differs from the native schema of the record. For
1705 instance, a client might only know how to process WAIS records, while
1706 the database record is represented in a more specific schema, such as
1707 GILS. In this module, a mapping of data to one of the MARC formats is
1708 also thought of as a schema mapping (mapping the elements of the
1709 record into fields consistent with the given MARC specification, prior
1710 to actually converting the data to the ISO2709). This use of the
1711 object identifier for USMARC as a schema identifier represents an
1712 overloading of the OID which might not be entirely proper. However,
1713 it represents the dual role of schema and record syntax which
1714 is assumed by the MARC family in Z39.50.
1718 <emphasis>NOTE: FIXME! The schema-mapping functions are so far limited to a
1719 straightforward mapping of elements. This should be extended with
1720 mechanisms for conversions of the element contents, and conditional
1721 mappings of elements based on the record contents.</emphasis>
1725 These are the directives of the schema mapping file format:
1732 <term>targetName <emphasis>name</emphasis></term>
1735 (m) A symbolic name for the target schema
1736 of the table. Useful mostly for diagnostic purposes.
1738 </listitem></varlistentry>
1740 <term>targetRef <emphasis>OID-name</emphasis></term>
1743 (m) An OID name for the target schema.
1744 This is used, for instance, by a server receiving a request to present
1745 a record in a different schema from the native one.
1746 The name, again, is found in the <emphasis>oid</emphasis>
1747 module of <emphasis>YAZ</emphasis>.
1749 </listitem></varlistentry>
1751 <term>map <emphasis>element-name target-path</emphasis></term>
1755 an element mapping rule to the table.
1757 </listitem></varlistentry>
1764 <title>The MARC (ISO2709) Representation (.mar) Files</title>
1767 This file provides rules for representing a record in the ISO2709
1768 format. The rules pertain mostly to the values of the constant-length
1769 header of the record.
1773 NOTE: FIXME! This will be described better. We're in the process of
1774 re-evaluating and most likely changing the way that MARC records are
1775 handled by the system.</emphasis>
1780 <sect2 id="field-structure-and-character-sets">
1781 <title>Field Structure and Character Sets
1785 In order to provide a flexible approach to national character set
1786 handling, Zebra allows the administrator to configure the set up the
1787 system to handle any 8-bit character set — including sets that
1788 require multi-octet diacritics or other multi-octet characters. The
1789 definition of a character set includes a specification of the
1790 permissible values, their sort order (this affects the display in the
1791 SCAN function), and relationships between upper- and lowercase
1792 characters. Finally, the definition includes the specification of
1793 space characters for the set.
1797 The operator can define different character sets for different fields,
1798 typical examples being standard text fields, numerical fields, and
1799 special-purpose fields such as WWW-style linkages (URx).
1802 <sect3 id="default-idx-file">
1803 <title>The default.idx file</title>
1805 The field types, and hence character sets, are associated with data
1806 elements by the .abs files (see above).
1807 The file <literal>default.idx</literal>
1808 provides the association between field type codes (as used in the .abs
1809 files) and the character map files (with the .chr suffix). The format
1810 of the .idx file is as follows
1817 <term>index <emphasis>field type code</emphasis></term>
1820 This directive introduces a new search index code.
1821 The argument is a one-character code to be used in the
1822 .abs files to select this particular index type. An index, roughly,
1823 corresponds to a particular structure attribute during search. Refer
1824 to <xref linkend="search"/>.
1826 </listitem></varlistentry>
1828 <term>sort <emphasis>field code type</emphasis></term>
1831 This directive introduces a
1832 sort index. The argument is a one-character code to be used in the
1833 .abs fie to select this particular index type. The corresponding
1834 use attribute must be used in the sort request to refer to this
1835 particular sort index. The corresponding character map (see below)
1836 is used in the sort process.
1838 </listitem></varlistentry>
1840 <term>completeness <emphasis>boolean</emphasis></term>
1843 This directive enables or disables complete field indexing.
1844 The value of the <emphasis>boolean</emphasis> should be 0
1845 (disable) or 1. If completeness is enabled, the index entry will
1846 contain the complete contents of the field (up to a limit), with words
1847 (non-space characters) separated by single space characters
1848 (normalized to " " on display). When completeness is
1849 disabled, each word is indexed as a separate entry. Complete subfield
1850 indexing is most useful for fields which are typically browsed (eg.
1851 titles, authors, or subjects), or instances where a match on a
1852 complete subfield is essential (eg. exact title searching). For fields
1853 where completeness is disabled, the search engine will interpret a
1854 search containing space characters as a word proximity search.
1856 </listitem></varlistentry>
1858 <term>charmap <emphasis>filename</emphasis></term>
1861 This is the filename of the character
1862 map to be used for this index for field type.
1864 </listitem></varlistentry>
1869 <sect3 id="character-map-files">
1870 <title>The character map file format</title>
1872 The contents of the character map files are structured as follows:
1879 <term>lowercase <emphasis>value-set</emphasis></term>
1882 This directive introduces the basic value set of the field type.
1883 The format is an ordered list (without spaces) of the
1884 characters which may occur in "words" of the given type.
1885 The order of the entries in the list determines the
1886 sort order of the index. In addition to single characters, the
1887 following combinations are legal:
1895 Backslashes may be used to introduce three-digit octal, or
1896 two-digit hex representations of single characters
1897 (preceded by <literal>x</literal>).
1898 In addition, the combinations
1899 \\, \\r, \\n, \\t, \\s (space — remember that real
1900 space-characters may not occur in the value definition), and
1901 \\ are recognized, with their usual interpretation.
1907 Curly braces {} may be used to enclose ranges of single
1908 characters (possibly using the escape convention described in the
1909 preceding point), eg. {a-z} to introduce the
1910 standard range of ASCII characters.
1911 Note that the interpretation of such a range depends on
1912 the concrete representation in your local, physical character set.
1918 paranthesises () may be used to enclose multi-byte characters -
1919 eg. diacritics or special national combinations (eg. Spanish
1920 "ll"). When found in the input stream (or a search term),
1921 these characters are viewed and sorted as a single character, with a
1922 sorting value depending on the position of the group in the value
1930 </listitem></varlistentry>
1932 <term>uppercase <emphasis>value-set</emphasis></term>
1935 This directive introduces the
1936 upper-case equivalencis to the value set (if any). The number and
1937 order of the entries in the list should be the same as in the
1938 <literal>lowercase</literal> directive.
1940 </listitem></varlistentry>
1942 <term>space <emphasis>value-set</emphasis></term>
1945 This directive introduces the character
1946 which separate words in the input stream. Depending on the
1947 completeness mode of the field in question, these characters either
1948 terminate an index entry, or delimit individual "words" in
1949 the input stream. The order of the elements is not significant —
1950 otherwise the representation is the same as for the
1951 <literal>uppercase</literal> and <literal>lowercase</literal>
1954 </listitem></varlistentry>
1956 <term>map <emphasis>value-set</emphasis>
1957 <emphasis>target</emphasis></term>
1960 This directive introduces a
1961 mapping between each of the members of the value-set on the left to
1962 the character on the right. The character on the right must occur in
1963 the value set (the <literal>lowercase</literal> directive) of
1964 the character set, but
1965 it may be a paranthesis-enclosed multi-octet character. This directive
1966 may be used to map diacritics to their base characters, or to map
1967 HTML-style character-representations to their natural form, etc. The map directive
1968 can also be used to ignore leading articles in searching and/or sorting, and to perform
1969 other special transformations. See section <xref linkend="leading-articles"/>.
1971 </listitem></varlistentry>
1975 <sect3 id="leading-articles">
1976 <title>Ignoring leading articles</title>
1978 In addition to specifying sort orders, space (blank) handling, and upper/lowercase folding,
1979 you can also use the character map files to make Zebra ignore leading articles in sorting
1980 records, or when doing complete field searching.
1983 This is done using the <literal>map</literal> directive in the character map file. In a
1984 nutshell, what you do is map certain sequences of characters, when they occur <emphasis>
1985 in the beginning of a field</emphasis>, to a space. Assuming that the character "@" is
1986 defined as a space character in your file, you can do:
1991 The effect of these directives is to map either 'the' or 'The', followed by a space
1992 character, to a space. The hat ^ character denotes beginning-of-field only when
1993 complete-subfield indexing or sort indexing is taking place; otherwise, it is treated just
1994 as any other character.
1997 Because the <literal>default.idx</literal> file can be used to associate different
1998 character maps with different indexing types -- and you can create additional indexing
1999 types, should the need arise -- it is possible to specify that leading articles should be
2000 ignored either in sorting, in complete-field searching, or both.
2003 If you ignore certain prefixes in sorting, then these will be eliminated from the index,
2004 and sorting will take place as if they weren't there. However, if you set the system up
2005 to ignore certain prefixes in <emphasis>searching</emphasis>, then these are deleted both
2006 from the indexes and from query terms, when the client specifies complete-field
2007 searching. This has the effect that a search for 'the science journal' and 'science
2008 journal' would both produce the same results.
2014 <sect1 id="formats">
2015 <title>Exchange Formats</title>
2018 Converting records from the internal structure to en exchange format
2019 is largely an automatic process. Currently, the following exchange
2020 formats are supported:
2027 GRS-1. The internal representation is based on GRS-1/XML, so the
2028 conversion here is straightforward. The system will create
2029 applied variant and supported variant lists as required, if a record
2030 contains variant information.
2036 XML. The internal representation is based on GRS-1/XML so
2037 the mapping is trivial. Note that XML schemas, preprocessing
2038 instructions and comments are not part of the internal representation
2039 and therefore will never be part of a generated XML record.
2040 Future versions of the Zebra will support that.
2046 SUTRS. Again, the mapping is fairly straightforward. Indentation
2047 is used to show the hierarchical structure of the record. All
2048 "GRS" type records support both the GRS-1 and SUTRS
2050 <!-- FIXME - What is SUTRS - should be expanded here -->
2056 ISO2709-based formats (USMARC, etc.). Only records with a
2057 two-level structure (corresponding to fields and subfields) can be
2058 directly mapped to ISO2709. For records with a different structuring
2059 (eg., GILS), the representation in a structure like USMARC involves a
2060 schema-mapping (see <xref linkend="schema-mapping"/>), to an
2061 "implied" USMARC schema (implied,
2062 because there is no formal schema which specifies the use of the
2063 USMARC fields outside of ISO2709). The resultant, two-level record is
2064 then mapped directly from the internal representation to ISO2709. See
2065 the GILS schema definition files for a detailed example of this
2072 Explain. This representation is only available for records
2073 belonging to the Explain schema.
2079 Summary. This ASN-1 based structure is only available for records
2080 belonging to the Summary schema - or schema which provide a mapping
2081 to this schema (see the description of the schema mapping facility
2088 SOIF. Support for this syntax is experimental, and is currently
2089 keyed to a private Index Data OID (1.2.840.10003.5.1000.81.2). All
2090 abstract syntaxes can be mapped to the SOIF format, although nested
2091 elements are represented by concatenation of the tag names at each
2093 <!-- FIXME - Is this used anywhere ? -H -->
2102 <!-- Keep this comment at the end of the file
2107 sgml-minimize-attributes:nil
2108 sgml-always-quote-attributes:t
2111 sgml-parent-document: "zebra.xml"
2112 sgml-local-catalogs: nil
2113 sgml-namecase-general:t
projects / idzebra-moved-to-github.git / blob