1 <chapter id="record-model">
2 <!-- $Id: recordmodel.xml,v 1.6 2002-10-10 14:27:18 heikki 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 schema 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> as introduced in
20 <xref linkend="record-types"/>.
21 FIXME - Need to describe the simple string-tag model, or at least
26 Records pass through three different states during processing in the
36 When records are accessed by the system, they are represented
37 in their local, or native format. This might be SGML or HTML files,
38 News or Mail archives, MARC records. If the system doesn't already
39 know how to read the type of data you need to store, you can set up an
40 input filter by preparing conversion rules based on regular
41 expressions and possibly augmented by a flexible scripting language
43 The input filter produces as output an internal representation:
50 When records are processed by the system, they are represented
51 in a tree-structure, constructed by tagged data elements hanging off a
52 root node. The tagged elements may contain data or yet more tagged
53 elements in a recursive structure. The system performs various
54 actions on this tree structure (indexing, element selection, schema
62 Before transmitting records to the client, they are first
63 converted from the internal structure to a form suitable for exchange
64 over the network - according to the Z39.50 standard.
72 <sect1 id="local-representation">
73 <title>Local Representation</title>
76 As mentioned earlier, Zebra places few restrictions on the type of
77 data that you can index and manage. Generally, whatever the form of
78 the data, it is parsed by an input filter specific to that format, and
79 turned into an internal structure that Zebra knows how to handle. This
80 process takes place whenever the record is accessed - for indexing and
85 The RecordType parameter in the <literal>zebra.cfg</literal> file, or
86 the <literal>-t</literal> option to the indexer tells Zebra how to
87 process input records.
88 Two basic types of processing are available - raw text and structured
89 data. Raw text is just that, and it is selected by providing the
90 argument <emphasis>text</emphasis> to Zebra. Structured records are
91 all handled internally using the basic mechanisms described in the
93 Zebra can read structured records in many different formats.
94 How this is done is governed by additional parameters after the
95 "grs" keyboard, separated by "." characters.
99 Four basic subtypes to the <emphasis>grs</emphasis> type are
106 <term>grs.sgml</term>
109 This is the canonical input format —
110 described below. It is a simple SGML-like syntax.
115 <term>grs.regx.<emphasis>filter</emphasis></term>
118 This enables a user-supplied input
119 filter. The mechanisms of these filters are described below.
124 <term>grs.tcl.<emphasis>filter</emphasis></term>
127 Similar to grs.regx but using Tcl for rules.
132 <term>grs.marc.<emphasis>abstract syntax</emphasis></term>
135 This allows Zebra to read
136 records in the ISO2709 (MARC) encoding standard. In this case, the
137 last parameter <emphasis>abstract syntax</emphasis> names the
138 <literal>.abs</literal> file (see below)
139 which describes the specific MARC structure of the input record as
140 well as the indexing rules.
148 This filter reads XML records. Only one record per file
149 is supported. The filter is only available if Zebra/YAZ
150 is compiled with EXPAT support.
159 <title>Canonical Input Format</title>
162 Although input data can take any form, it is sometimes useful to
163 describe the record processing capabilities of the system in terms of
164 a single, canonical input format that gives access to the full
165 spectrum of structure and flexibility in the system. In Zebra, this
166 canonical format is an "SGML-like" syntax.
170 To use the canonical format specify <literal>grs.sgml</literal> as
175 Consider a record describing an information resource (such a record is
176 sometimes known as a <emphasis>locator record</emphasis>).
177 It might contain a field describing the distributor of the
178 information resource, which might in turn be partitioned into
179 various fields providing details about the distributor, like this:
185 <Distributor>
186 <Name> USGS/WRD </Name>
187 <Organization> USGS/WRD </Organization>
188 <Street-Address>
189 U.S. GEOLOGICAL SURVEY, 505 MARQUETTE, NW
190 </Street-Address>
191 <City> ALBUQUERQUE </City>
192 <State> NM </State>
193 <Zip-Code> 87102 </Zip-Code>
194 <Country> USA </Country>
195 <Telephone> (505) 766-5560 </Telephone>
196 </Distributor>
201 <!-- There is no indentation in the example above! -H
204 The indentation used above is used to illustrate how Zebra
205 interprets the mark-up. The indentation, in itself, has no
206 significance to the parser for the canonical input format, which
207 discards superfluous whitespace.
213 The keywords surrounded by <...> are
214 <emphasis>tags</emphasis>, while the sections of text
215 in between are the <emphasis>data elements</emphasis>.
216 A data element is characterized by its location in the tree
217 that is made up by the nested elements.
218 Each element is terminated by a closing tag - beginning
219 with <literal><</literal>/, and containing the same symbolic
220 tag-name as the corresponding opening tag.
221 The general closing tag - <literal><</literal>>/ -
222 terminates the element started by the last opening tag. The
223 structuring of elements is significant.
224 The element <emphasis>Telephone</emphasis>,
225 for instance, may be indexed and presented to the client differently,
226 depending on whether it appears inside the
227 <emphasis>Distributor</emphasis> element, or some other,
228 structured data element such a <emphasis>Supplier</emphasis> element.
232 <title>Record Root</title>
235 The first tag in a record describes the root node of the tree that
236 makes up the total record. In the canonical input format, the root tag
237 should contain the name of the schema that lends context to the
238 elements of the record
239 (see <xref linkend="internal-representation"/>).
240 The following is a GILS record that
241 contains only a single element (strictly speaking, that makes it an
242 illegal GILS record, since the GILS profile includes several mandatory
243 elements - Zebra does not validate the contents of a record against
244 the Z39.50 profile, however - it merely attempts to match up elements
245 of a local representation with the given schema):
252 <title>Zen and the Art of Motorcycle Maintenance</title>
261 <title>Variants</title>
264 Zebra allows you to provide individual data elements in a number of
265 <emphasis>variant forms</emphasis>. Examples of variant forms are
266 textual data elements which might appear in different languages, and
267 images which may appear in different formats or layouts.
268 The variant system in Zebra is essentially a representation of
269 the variant mechanism of Z39.50-1995.
273 The following is an example of a title element which occurs in two
281 <var lang lang "eng">
282 Zen and the Art of Motorcycle Maintenance</>
283 <var lang lang "dan">
284 Zen og Kunsten at Vedligeholde en Motorcykel</>
291 The syntax of the <emphasis>variant element</emphasis> is
292 <literal><var class type value></literal>.
293 The available values for the <emphasis>class</emphasis> and
294 <emphasis>type</emphasis> fields are given by the variant set
295 that is associated with the current schema
296 (see <xref linkend="variant-set"/>).
300 Variant elements are terminated by the general end-tag </>, by
301 the variant end-tag </var>, by the appearance of another variant
302 tag with the same <emphasis>class</emphasis> and
303 <emphasis>value</emphasis> settings, or by the
304 appearance of another, normal tag. In other words, the end-tags for
305 the variants used in the example above could have been saved.
309 Variant elements can be nested. The element
316 <var lang lang "eng"><var body iana "text/plain">
317 Zen and the Art of Motorcycle Maintenance
324 Associates two variant components to the variant list for the title
329 Given the nesting rules described above, we could write
336 <var body iana "text/plain>
337 <var lang lang "eng">
338 Zen and the Art of Motorcycle Maintenance
339 <var lang lang "dan">
340 Zen og Kunsten at Vedligeholde en Motorcykel
347 The title element above comes in two variants. Both have the IANA body
348 type "text/plain", but one is in English, and the other in
349 Danish. The client, using the element selection mechanism of Z39.50,
350 can retrieve information about the available variant forms of data
351 elements, or it can select specific variants based on the requirements
360 <title>Input Filters</title>
363 In order to handle general input formats, Zebra allows the
364 operator to define filters which read individual records in their
365 native format and produce an internal representation that the system
370 Input filters are ASCII files, generally with the suffix
371 <literal>.flt</literal>.
372 The system looks for the files in the directories given in the
373 <emphasis>profilePath</emphasis> setting in the
374 <literal>zebra.cfg</literal> files.
375 The record type for the filter is
376 <literal>grs.regx.</literal><emphasis>filter-filename</emphasis>
377 (fundamental type <literal>grs</literal>, file read
378 type <literal>regx</literal>, argument
379 <emphasis>filter-filename</emphasis>).
383 Generally, an input filter consists of a sequence of rules, where each
384 rule consists of a sequence of expressions, followed by an action. The
385 expressions are evaluated against the contents of the input record,
386 and the actions normally contribute to the generation of an internal
387 representation of the record.
391 An expression can be either of the following:
401 The action associated with this expression is evaluated
402 exactly once in the lifetime of the application, before any records
403 are read. It can be used in conjunction with an action that
404 initializes tables or other resources that are used in the processing
413 Matches the beginning of the record. It can be used to
414 initialize variables, etc. Typically, the
415 <emphasis>BEGIN</emphasis> rule is also used
416 to establish the root node of the record.
424 Matches the end of the record - when all of the contents
425 of the record has been processed.
430 <term>/pattern/</term>
433 Matches a string of characters from the input record.
441 This keyword may only be used between two patterns.
442 It matches everything between (not including) those patterns.
450 The expression associated with this pattern is evaluated
451 once, before the application terminates. It can be used to release
452 system resources - typically ones allocated in the
453 <emphasis>INIT</emphasis> step.
461 An action is surrounded by curly braces ({...}), and
462 consists of a sequence of statements. Statements may be separated
463 by newlines or semicolons (;).
464 Within actions, the strings that matched the expressions
465 immediately preceding the action can be referred to as
466 $0, $1, $2, etc.
470 The available statements are:
477 <term>begin <emphasis>type [parameter ... ]</emphasis></term>
481 data element. The type is one of the following:
488 Begin a new record. The following parameter should be the
489 name of the schema that describes the structure of the record, eg.
490 <literal>gils</literal> or <literal>wais</literal> (see below).
491 The <literal>begin record</literal> call should precede
492 any other use of the <emphasis>begin</emphasis> statement.
500 Begin a new tagged element. The parameter is the
501 name of the tag. If the tag is not matched anywhere in the tagsets
502 referenced by the current schema, it is treated as a local string
511 Begin a new node in a variant tree. The parameters are
512 <emphasis>class type value</emphasis>.
524 Create a data element. The concatenated arguments make
525 up the value of the data element.
526 The option <literal>-text</literal> signals that
527 the layout (whitespace) of the data should be retained for
529 The option <literal>-element</literal>
530 <emphasis>tag</emphasis> wraps the data up in
531 the <emphasis>tag</emphasis>.
532 The use of the <literal>-element</literal> option is equivalent to
533 preceding the command with a <emphasis>begin
534 element</emphasis> command, and following
535 it with the <emphasis>end</emphasis> command.
540 <term>end <emphasis>[type]</emphasis></term>
543 Close a tagged element. If no parameter is given,
544 the last element on the stack is terminated.
545 The first parameter, if any, is a type name, similar
546 to the <emphasis>begin</emphasis> statement.
547 For the <emphasis>element</emphasis> type, a tag
548 name can be provided to terminate a specific tag.
556 The following input filter reads a Usenet news file, producing a
557 record in the WAIS schema. Note that the body of a news posting is
558 separated from the list of headers by a blank line (or rather a
559 sequence of two newline characters.
565 BEGIN { begin record wais }
567 /^From:/ BODY /$/ { data -element name $1 }
568 /^Subject:/ BODY /$/ { data -element title $1 }
569 /^Date:/ BODY /$/ { data -element lastModified $1 }
571 begin element bodyOfDisplay
572 begin variant body iana "text/plain"
581 If Zebra is compiled with support for Tcl (Tool Command Language)
582 enabled, the statements described above are supplemented with a complete
583 scripting environment, including control structures (conditional
584 expressions and loop constructs), and powerful string manipulation
585 mechanisms for modifying the elements of a record. Tcl is a popular
586 scripting environment, with several tutorials available both online
594 <sect1 id="internal-representation">
595 <title>Internal Representation</title>
598 When records are manipulated by the system, they're represented in a
599 tree-structure, with data elements at the leaf nodes, and tags or
600 variant components at the non-leaf nodes. The root-node identifies the
601 schema that lends context to the tagging and structuring of the
602 record. Imagine a simple record, consisting of a 'title' element and
609 TITLE "Zen and the Art of Motorcycle Maintenance"
611 AUTHOR "Robert Pirsig"
613 <!-- FIXME That screen makes no sense! -H -->
618 A slightly more complex record would have the author element consist
619 of two elements, a surname and a first name:
625 TITLE "Zen and the Art of Motorcycle Maintenance"
631 <!-- FIXME That screen makes even less sense! -H -->
636 The root of the record will refer to the record schema that describes
637 the structuring of this particular record. The schema defines the
638 element tags (TITLE, FIRST-NAME, etc.) that may occur in the record, as
639 well as the structuring (SURNAME should appear below AUTHOR, etc.). In
640 addition, the schema establishes element set names that are used by
641 the client to request a subset of the elements of a given record. The
642 schema may also establish rules for converting the record to a
643 different schema, by stating, for each element, a mapping to a
648 <title>Tagged Elements</title>
651 A data element is characterized by its tag, and its position in the
652 structure of the record. For instance, while the tag "telephone
653 number" may be used different places in a record, we may need to
654 distinguish between these occurrences, both for searching and
655 presentation purposes. For instance, while the phone numbers for the
656 "customer" and the "service provider" are both
657 representatives for the same type of resource (a telephone number), it
658 is essential that they be kept separate. The record schema provides
659 the structure of the record, and names each data element (defined by
660 the sequence of tags - the tag path - by which the element can be
661 reached from the root of the record).
667 <title>Variants</title>
670 The children of a tag node may be either more tag nodes, a data node
671 (possibly accompanied by tag nodes),
672 or a tree of variant nodes. The children of variant nodes are either
673 more variant nodes or a data node (possibly accompanied by more
674 variant nodes). Each leaf node, which is normally a
675 data node, corresponds to a <emphasis>variant form</emphasis> of the
676 tagged element identified by the tag which parents the variant tree.
677 The following title element occurs in two different languages:
683 VARIANT LANG=ENG "War and Peace"
685 VARIANT LANG=DAN "Krig og Fred"
691 Which of the two elements are transmitted to the client by the server
692 depends on the specifications provided by the client, if any.
696 In practice, each variant node is associated with a triple of class,
697 type, value, corresponding to the variant mechanism of Z39.50.
703 <title>Data Elements</title>
706 Data nodes have no children (they are always leaf nodes in the record
712 FIXME! Documentation needs extension here about types of nodes - numerical,
713 textual, etc., plus the various types of inclusion notes.
721 <sect1 id="data-model">
722 <title>Configuring Your Data Model</title>
725 The following sections describe the configuration files that govern
726 the internal management of data records. The system searches for the files
727 in the directories specified by the <emphasis>profilePath</emphasis>
728 setting in the <literal>zebra.cfg</literal> file.
732 <title>The Abstract Syntax</title>
735 The abstract syntax definition (also known as an Abstract Record
736 Structure, or ARS) is the focal point of the
737 record schema description. For a given schema, the ABS file may state any
738 or all of the following:
742 FIXME - Need a diagram here, or a simple explanation how it all hangs together -H
751 The object identifier of the Z39.50 schema associated
752 with the ARS, so that it can be referred to by the client.
758 The attribute set (which can possibly be a compound of multiple
759 sets) which applies in the profile. This is used when indexing and
760 searching the records belonging to the given profile.
766 The Tag set (again, this can consist of several different sets).
767 This is used when reading the records from a file, to recognize the
768 different tags, and when transmitting the record to the client -
769 mapping the tags to their numerical representation, if they are
776 The variant set which is used in the profile. This provides a
777 vocabulary for specifying the <emphasis>forms</emphasis> of
778 data that appear inside the records.
784 Element set names, which are a shorthand way for the client to
785 ask for a subset of the data elements contained in a record. Element
786 set names, in the retrieval module, are mapped to <emphasis>element
787 specifications</emphasis>, which contain information equivalent to the
788 <emphasis>Espec-1</emphasis> syntax of Z39.50.
794 Map tables, which may specify mappings to
795 <emphasis>other</emphasis> database profiles, if desired.
801 Possibly, a set of rules describing the mapping of elements to a
809 A list of element descriptions (this is the actual ARS of the
810 schema, in Z39.50 terms), which lists the ways in which the various
811 tags can be used and organized hierarchically.
820 Several of the entries above simply refer to other files, which
821 describe the given objects.
827 <title>The Configuration Files</title>
830 This section describes the syntax and use of the various tables which
831 are used by the retrieval module.
835 The number of different file types may appear daunting at first, but
836 each type corresponds fairly clearly to a single aspect of the Z39.50
837 retrieval facilities. Further, the average database administrator,
838 who is simply reusing an existing profile for which tables already
839 exist, shouldn't have to worry too much about the contents of these tables.
843 Generally, the files are simple ASCII files, which can be maintained
844 using any text editor. Blank lines, and lines beginning with a (#) are
845 ignored. Any characters on a line followed by a (#) are also ignored.
846 All other lines contain <emphasis>directives</emphasis>, which provide
847 some setting or value to the system.
848 Generally, settings are characterized by a single
849 keyword, identifying the setting, followed by a number of parameters.
850 Some settings are repeatable (r), while others may occur only once in a
851 file. Some settings are optional (o), while others again are
858 <title>The Abstract Syntax (.abs) Files</title>
861 The name of this file type is slightly misleading in Z39.50 terms,
862 since, apart from the actual abstract syntax of the profile, it also
863 includes most of the other definitions that go into a database
868 When a record in the canonical, SGML-like format is read from a file
869 or from the database, the first tag of the file should reference the
870 profile that governs the layout of the record. If the first tag of the
871 record is, say, <literal><gils></literal>, the system will look
872 for the profile definition in the file <literal>gils.abs</literal>.
873 Profile definitions are cached, so they only have to be read once
874 during the lifespan of the current process.
878 When writing your own input filters, the
879 <emphasis>record-begin</emphasis> command
880 introduces the profile, and should always be called first thing when
881 introducing a new record.
885 The file may contain the following directives:
892 <term>name <emphasis>symbolic-name</emphasis></term>
895 (m) This provides a shorthand name or
896 description for the profile. Mostly useful for diagnostic purposes.
901 <term>reference <emphasis>OID-name</emphasis></term>
904 (m) The reference name of the OID for the profile.
905 The reference names can be found in the <emphasis>util</emphasis>
906 module of <emphasis>YAZ</emphasis>.
911 <term>attset <emphasis>filename</emphasis></term>
914 (m) The attribute set that is used for
915 indexing and searching records belonging to this profile.
920 <term>tagset <emphasis>filename</emphasis></term>
923 (o) The tag set (if any) that describe
924 that fields of the records.
929 <term>varset <emphasis>filename</emphasis></term>
932 (o) The variant set used in the profile.
937 <term>maptab <emphasis>filename</emphasis></term>
940 (o,r) This points to a
941 conversion table that might be used if the client asks for the record
942 in a different schema from the native one.
944 </listitem></varlistentry>
946 <term>marc <emphasis>filename</emphasis></term>
949 (o) Points to a file containing parameters
950 for representing the record contents in the ISO2709 syntax. Read the
951 description of the MARC representation facility below.
953 </listitem></varlistentry>
955 <term>esetname <emphasis>name filename</emphasis></term>
959 given element set name with an element selection file. If an (@) is
960 given in place of the filename, this corresponds to a null mapping for
961 the given element set name.
963 </listitem></varlistentry>
965 <term>any <emphasis>tags</emphasis></term>
968 (o) This directive specifies a list of attributes
969 which should be appended to the attribute list given for each
970 element. The effect is to make every single element in the abstract
971 syntax searchable by way of the given attributes. This directive
972 provides an efficient way of supporting free-text searching across all
973 elements. However, it does increase the size of the index
974 significantly. The attributes can be qualified with a structure, as in
975 the <emphasis>elm</emphasis> directive below.
977 </listitem></varlistentry>
979 <term>elm <emphasis>path name attributes</emphasis></term>
982 (o,r) Adds an element to the abstract record syntax of the schema.
983 The <emphasis>path</emphasis> follows the
984 syntax which is suggested by the Z39.50 document - that is, a sequence
985 of tags separated by slashes (/). Each tag is given as a
986 comma-separated pair of tag type and -value surrounded by parenthesis.
987 The <emphasis>name</emphasis> is the name of the element, and
988 the <emphasis>attributes</emphasis>
989 specifies which attributes to use when indexing the element in a
990 comma-separated list.
991 A ! in place of the attribute name is equivalent to
992 specifying an attribute name identical to the element name.
993 A - in place of the attribute name
994 specifies that no indexing is to take place for the given element.
995 The attributes can be qualified with <emphasis>field
996 types</emphasis> to specify which
997 character set should govern the indexing procedure for that field.
998 The same data element may be indexed into several different
999 fields, using different character set definitions.
1000 See the <xref linkend="field-structure-and-character-sets"/>.
1001 The default field type is "w" for <emphasis>word</emphasis>.
1003 </listitem></varlistentry>
1005 <term>encoding <emphasis>encodingname</emphasis></term>
1008 This directive specifies character encoding for external records.
1009 For records such as XML that specifies encoding within the
1010 file via a header this directive is ignored.
1011 If neither this directive is given, nor an encoding is set
1012 within external records, ISO-8859-1 encoding is assmed.
1017 <term>xpath <emphasis>enable/disable</emphasis></term>
1020 If this directive is followed by <literal>enable</literal>,
1021 then extra indexing is performed to allow for XPath-like queries.
1022 If this directive is not specified - equivalent to
1023 <literal>disable</literal> - no extra XPath-indexing is performed.
1032 The mechanism for controlling indexing is not adequate for
1033 complex databases, and will probably be moved into a separate
1034 configuration table eventually.
1039 The following is an excerpt from the abstract syntax file for the GILS
1047 reference GILS-schema
1052 maptab gils-usmarc.map
1056 esetname VARIANT gils-variant.est # for WAIS-compliance
1057 esetname B gils-b.est
1058 esetname G gils-g.est
1063 elm (1,14) localControlNumber Local-number
1064 elm (1,16) dateOfLastModification Date/time-last-modified
1065 elm (2,1) title w:!,p:!
1066 elm (4,1) controlIdentifier Identifier-standard
1067 elm (2,6) abstract Abstract
1068 elm (4,51) purpose !
1069 elm (4,52) originator -
1070 elm (4,53) accessConstraints !
1071 elm (4,54) useConstraints !
1072 elm (4,70) availability -
1073 elm (4,70)/(4,90) distributor -
1074 elm (4,70)/(4,90)/(2,7) distributorName !
1075 elm (4,70)/(4,90)/(2,10 distributorOrganization !
1076 elm (4,70)/(4,90)/(4,2) distributorStreetAddress !
1077 elm (4,70)/(4,90)/(4,3) distributorCity !
1084 <sect2 id="attset-files">
1085 <title>The Attribute Set (.att) Files</title>
1088 This file type describes the <emphasis>Use</emphasis> elements of
1090 It contains the following directives.
1096 <term>name <emphasis>symbolic-name</emphasis></term>
1099 (m) This provides a shorthand name or
1100 description for the attribute set.
1101 Mostly useful for diagnostic purposes.
1103 </listitem></varlistentry>
1105 <term>reference <emphasis>OID-name</emphasis></term>
1108 (m) The reference name of the OID for
1110 The reference names can be found in the <emphasis>util</emphasis>
1111 module of <emphasis>YAZ</emphasis>.
1113 </listitem></varlistentry>
1115 <term>include <emphasis>filename</emphasis></term>
1118 (o,r) This directive is used to
1119 include another attribute set as a part of the current one. This is
1120 used when a new attribute set is defined as an extension to another
1121 set. For instance, many new attribute sets are defined as extensions
1122 to the <emphasis>bib-1</emphasis> set.
1123 This is an important feature of the retrieval
1124 system of Z39.50, as it ensures the highest possible level of
1125 interoperability, as those access points of your database which are
1126 derived from the external set (say, bib-1) can be used even by clients
1127 who are unaware of the new set.
1129 </listitem></varlistentry>
1132 <emphasis>att-value att-name [local-value]</emphasis></term>
1136 repeatable directive introduces a new attribute to the set. The
1137 attribute value is stored in the index (unless a
1138 <emphasis>local-value</emphasis> is
1139 given, in which case this is stored). The name is used to refer to the
1140 attribute from the <emphasis>abstract syntax</emphasis>.
1142 </listitem></varlistentry>
1147 This is an excerpt from the GILS attribute set definition.
1148 Notice how the file describing the <emphasis>bib-1</emphasis>
1149 attribute set is referenced.
1156 reference GILS-attset
1159 att 2001 distributorName
1160 att 2002 indextermsControlled
1162 att 2004 accessConstraints
1163 att 2005 useConstraints
1171 <title>The Tag Set (.tag) Files</title>
1174 This file type defines the tagset of the profile, possibly by
1175 referencing other tag sets (most tag sets, for instance, will include
1176 tagsetG and tagsetM from the Z39.50 specification. The file may
1177 contain the following directives.
1184 <term>name <emphasis>symbolic-name</emphasis></term>
1187 (m) This provides a shorthand name or
1188 description for the tag set. Mostly useful for diagnostic purposes.
1190 </listitem></varlistentry>
1192 <term>reference <emphasis>OID-name</emphasis></term>
1195 (o) The reference name of the OID for the tag set.
1196 The reference names can be found in the <emphasis>util</emphasis>
1197 module of <emphasis>YAZ</emphasis>.
1198 The directive is optional, since not all tag sets
1199 are registered outside of their schema.
1201 </listitem></varlistentry>
1203 <term>type <emphasis>integer</emphasis></term>
1206 (m) The type number of the tagset within the schema
1207 profile (note: this specification really should belong to the .abs
1208 file. This will be fixed in a future release).
1210 </listitem></varlistentry>
1212 <term>include <emphasis>filename</emphasis></term>
1215 (o,r) This directive is used
1216 to include the definitions of other tag sets into the current one.
1218 </listitem></varlistentry>
1220 <term>tag <emphasis>number names type</emphasis></term>
1223 (o,r) Introduces a new tag to the set.
1224 The <emphasis>number</emphasis> is the tag number as used
1225 in the protocol (there is currently no mechanism for
1226 specifying string tags at this point, but this would be quick
1228 The <emphasis>names</emphasis> parameter is a list of names
1229 by which the tag should be recognized in the input file format.
1230 The names should be separated by slashes (/).
1231 The <emphasis>type</emphasis> is the recommended data type of
1233 It should be one of the following:
1299 </listitem></varlistentry>
1304 The following is an excerpt from the TagsetG definition file.
1315 tag 3 publicationPlace string
1316 tag 4 publicationDate string
1317 tag 5 documentId string
1318 tag 6 abstract string
1320 tag 8 date generalizedtime
1321 tag 9 bodyOfDisplay string
1322 tag 10 organization string
1328 <sect2 id="variant-set">
1329 <title>The Variant Set (.var) Files</title>
1332 The variant set file is a straightforward representation of the
1333 variant set definitions associated with the protocol. At present, only
1334 the <emphasis>Variant-1</emphasis> set is known.
1338 These are the directives allowed in the file.
1345 <term>name <emphasis>symbolic-name</emphasis></term>
1348 (m) This provides a shorthand name or
1349 description for the variant set. Mostly useful for diagnostic purposes.
1351 </listitem></varlistentry>
1353 <term>reference <emphasis>OID-name</emphasis></term>
1356 (o) The reference name of the OID for
1357 the variant set, if one is required. The reference names can be found
1358 in the <emphasis>util</emphasis> module of <emphasis>YAZ</emphasis>.
1360 </listitem></varlistentry>
1362 <term>class <emphasis>integer class-name</emphasis></term>
1365 (m,r) Introduces a new
1366 class to the variant set.
1368 </listitem></varlistentry>
1370 <term>type <emphasis>integer type-name datatype</emphasis></term>
1374 new type to the current class (the one introduced by the most recent
1375 <emphasis>class</emphasis> directive).
1376 The type names belong to the same name space as the one used
1377 in the tag set definition file.
1379 </listitem></varlistentry>
1384 The following is an excerpt from the file describing the variant set
1385 <emphasis>Variant-1</emphasis>.
1396 type 1 variantId octetstring
1401 type 2 z39.50 string
1410 <title>The Element Set (.est) Files</title>
1413 The element set specification files describe a selection of a subset
1414 of the elements of a database record. The element selection mechanism
1415 is equivalent to the one supplied by the <emphasis>Espec-1</emphasis>
1416 syntax of the Z39.50 specification.
1417 In fact, the internal representation of an element set
1418 specification is identical to the <emphasis>Espec-1</emphasis> structure,
1419 and we'll refer you to the description of that structure for most of
1420 the detailed semantics of the directives below.
1425 Not all of the Espec-1 functionality has been implemented yet.
1426 The fields that are mentioned below all work as expected, unless
1432 The directives available in the element set file are as follows:
1438 <term>defaultVariantSetId <emphasis>OID-name</emphasis></term>
1441 (o) If variants are used in
1442 the following, this should provide the name of the variantset used
1443 (it's not currently possible to specify a different set in the
1444 individual variant request). In almost all cases (certainly all
1445 profiles known to us), the name
1446 <literal>Variant-1</literal> should be given here.
1448 </listitem></varlistentry>
1450 <term>defaultVariantRequest <emphasis>variant-request</emphasis></term>
1454 provides a default variant request for
1455 use when the individual element requests (see below) do not contain a
1456 variant request. Variant requests consist of a blank-separated list of
1457 variant components. A variant compont is a comma-separated,
1458 parenthesized triple of variant class, type, and value (the two former
1459 values being represented as integers). The value can currently only be
1460 entered as a string (this will change to depend on the definition of
1461 the variant in question). The special value (@) is interpreted as a
1462 null value, however.
1464 </listitem></varlistentry>
1467 <emphasis>path ['variant' variant-request]</emphasis></term>
1470 (o,r) This corresponds to a simple element request
1471 in <emphasis>Espec-1</emphasis>.
1472 The path consists of a sequence of tag-selectors, where each of
1473 these can consist of either:
1480 A simple tag, consisting of a comma-separated type-value pair in
1481 parenthesis, possibly followed by a colon (:) followed by an
1482 occurrences-specification (see below). The tag-value can be a number
1483 or a string. If the first character is an apostrophe ('), this
1484 forces the value to be interpreted as a string, even if it
1485 appears to be numerical.
1491 A WildThing, represented as a question mark (?), possibly
1492 followed by a colon (:) followed by an occurrences
1493 specification (see below).
1499 A WildPath, represented as an asterisk (*). Note that the last
1500 element of the path should not be a wildPath (wildpaths don't
1501 work in this version).
1510 The occurrences-specification can be either the string
1511 <literal>all</literal>, the string <literal>last</literal>, or
1512 an explicit value-range. The value-range is represented as
1513 an integer (the starting point), possibly followed by a
1514 plus (+) and a second integer (the number of elements, default
1519 The variant-request has the same syntax as the defaultVariantRequest
1520 above. Note that it may sometimes be useful to give an empty variant
1521 request, simply to disable the default for a specific set of fields
1522 (we aren't certain if this is proper <emphasis>Espec-1</emphasis>,
1523 but it works in this implementation).
1525 </listitem></varlistentry>
1530 The following is an example of an element specification belonging to
1537 simpleelement (1,10)
1538 simpleelement (1,12)
1540 simpleelement (1,14)
1542 simpleelement (4,52)
1549 <sect2 id="schema-mapping">
1550 <title>The Schema Mapping (.map) Files</title>
1553 Sometimes, the client might want to receive a database record in
1554 a schema that differs from the native schema of the record. For
1555 instance, a client might only know how to process WAIS records, while
1556 the database record is represented in a more specific schema, such as
1557 GILS. In this module, a mapping of data to one of the MARC formats is
1558 also thought of as a schema mapping (mapping the elements of the
1559 record into fields consistent with the given MARC specification, prior
1560 to actually converting the data to the ISO2709). This use of the
1561 object identifier for USMARC as a schema identifier represents an
1562 overloading of the OID which might not be entirely proper. However,
1563 it represents the dual role of schema and record syntax which
1564 is assumed by the MARC family in Z39.50.
1568 <emphasis>NOTE: FIXME! The schema-mapping functions are so far limited to a
1569 straightforward mapping of elements. This should be extended with
1570 mechanisms for conversions of the element contents, and conditional
1571 mappings of elements based on the record contents.</emphasis>
1575 These are the directives of the schema mapping file format:
1582 <term>targetName <emphasis>name</emphasis></term>
1585 (m) A symbolic name for the target schema
1586 of the table. Useful mostly for diagnostic purposes.
1588 </listitem></varlistentry>
1590 <term>targetRef <emphasis>OID-name</emphasis></term>
1593 (m) An OID name for the target schema.
1594 This is used, for instance, by a server receiving a request to present
1595 a record in a different schema from the native one.
1596 The name, again, is found in the <emphasis>oid</emphasis>
1597 module of <emphasis>YAZ</emphasis>.
1599 </listitem></varlistentry>
1601 <term>map <emphasis>element-name target-path</emphasis></term>
1605 an element mapping rule to the table.
1607 </listitem></varlistentry>
1614 <title>The MARC (ISO2709) Representation (.mar) Files</title>
1617 This file provides rules for representing a record in the ISO2709
1618 format. The rules pertain mostly to the values of the constant-length
1619 header of the record.
1623 <emphasis>NOTE: FIXME! This will be described better. We're in the process of
1624 re-evaluating and most likely changing the way that MARC records are
1625 handled by the system.</emphasis>
1630 <sect2 id="field-structure-and-character-sets">
1631 <title>Field Structure and Character Sets
1635 In order to provide a flexible approach to national character set
1636 handling, Zebra allows the administrator to configure the set up the
1637 system to handle any 8-bit character set — including sets that
1638 require multi-octet diacritics or other multi-octet characters. The
1639 definition of a character set includes a specification of the
1640 permissible values, their sort order (this affects the display in the
1641 SCAN function), and relationships between upper- and lowercase
1642 characters. Finally, the definition includes the specification of
1643 space characters for the set.
1647 The operator can define different character sets for different fields,
1648 typical examples being standard text fields, numerical fields, and
1649 special-purpose fields such as WWW-style linkages (URx).
1653 The field types, and hence character sets, are associated with data
1654 elements by the .abs files (see above).
1655 The file <literal>default.idx</literal>
1656 provides the association between field type codes (as used in the .abs
1657 files) and the character map files (with the .chr suffix). The format
1658 of the .idx file is as follows
1665 <term>index <emphasis>field type code</emphasis></term>
1668 This directive introduces a new search index code.
1669 The argument is a one-character code to be used in the
1670 .abs files to select this particular index type. An index, roughly,
1671 corresponds to a particular structure attribute during search. Refer
1672 to <xref linkend="search"/>.
1674 </listitem></varlistentry>
1676 <term>sort <emphasis>field code type</emphasis></term>
1679 This directive introduces a
1680 sort index. The argument is a one-character code to be used in the
1681 .abs fie to select this particular index type. The corresponding
1682 use attribute must be used in the sort request to refer to this
1683 particular sort index. The corresponding character map (see below)
1684 is used in the sort process.
1686 </listitem></varlistentry>
1688 <term>completeness <emphasis>boolean</emphasis></term>
1691 This directive enables or disables complete field indexing.
1692 The value of the <emphasis>boolean</emphasis> should be 0
1693 (disable) or 1. If completeness is enabled, the index entry will
1694 contain the complete contents of the field (up to a limit), with words
1695 (non-space characters) separated by single space characters
1696 (normalized to " " on display). When completeness is
1697 disabled, each word is indexed as a separate entry. Complete subfield
1698 indexing is most useful for fields which are typically browsed (eg.
1699 titles, authors, or subjects), or instances where a match on a
1700 complete subfield is essential (eg. exact title searching). For fields
1701 where completeness is disabled, the search engine will interpret a
1702 search containing space characters as a word proximity search.
1704 </listitem></varlistentry>
1706 <term>charmap <emphasis>filename</emphasis></term>
1709 This is the filename of the character
1710 map to be used for this index for field type.
1712 </listitem></varlistentry>
1717 The contents of the character map files are structured as follows:
1724 <term>lowercase <emphasis>value-set</emphasis></term>
1727 This directive introduces the basic value set of the field type.
1728 The format is an ordered list (without spaces) of the
1729 characters which may occur in "words" of the given type.
1730 The order of the entries in the list determines the
1731 sort order of the index. In addition to single characters, the
1732 following combinations are legal:
1740 Backslashes may be used to introduce three-digit octal, or
1741 two-digit hex representations of single characters
1742 (preceded by <literal>x</literal>).
1743 In addition, the combinations
1744 \\, \\r, \\n, \\t, \\s (space — remember that real
1745 space-characters may not occur in the value definition), and
1746 \\ are recognized, with their usual interpretation.
1752 Curly braces {} may be used to enclose ranges of single
1753 characters (possibly using the escape convention described in the
1754 preceding point), eg. {a-z} to introduce the
1755 standard range of ASCII characters.
1756 Note that the interpretation of such a range depends on
1757 the concrete representation in your local, physical character set.
1763 paranthesises () may be used to enclose multi-byte characters -
1764 eg. diacritics or special national combinations (eg. Spanish
1765 "ll"). When found in the input stream (or a search term),
1766 these characters are viewed and sorted as a single character, with a
1767 sorting value depending on the position of the group in the value
1775 </listitem></varlistentry>
1777 <term>uppercase <emphasis>value-set</emphasis></term>
1780 This directive introduces the
1781 upper-case equivalencis to the value set (if any). The number and
1782 order of the entries in the list should be the same as in the
1783 <literal>lowercase</literal> directive.
1785 </listitem></varlistentry>
1787 <term>space <emphasis>value-set</emphasis></term>
1790 This directive introduces the character
1791 which separate words in the input stream. Depending on the
1792 completeness mode of the field in question, these characters either
1793 terminate an index entry, or delimit individual "words" in
1794 the input stream. The order of the elements is not significant —
1795 otherwise the representation is the same as for the
1796 <literal>uppercase</literal> and <literal>lowercase</literal>
1799 </listitem></varlistentry>
1801 <term>map <emphasis>value-set</emphasis>
1802 <emphasis>target</emphasis></term>
1805 This directive introduces a
1806 mapping between each of the members of the value-set on the left to
1807 the character on the right. The character on the right must occur in
1808 the value set (the <literal>lowercase</literal> directive) of
1809 the character set, but
1810 it may be a paranthesis-enclosed multi-octet character. This directive
1811 may be used to map diacritics to their base characters, or to map
1812 HTML-style character-representations to their natural form, etc.
1814 </listitem></varlistentry>
1822 <sect1 id="formats">
1823 <title>Exchange Formats</title>
1826 Converting records from the internal structure to en exchange format
1827 is largely an automatic process. Currently, the following exchange
1828 formats are supported:
1835 GRS-1. The internal representation is based on GRS-1/XML, so the
1836 conversion here is straightforward. The system will create
1837 applied variant and supported variant lists as required, if a record
1838 contains variant information.
1844 XML. The internal representation is based on GRS-1/XML so
1845 the mapping is trivial. Note that XML schemas, preprocessing
1846 instructions and comments are not part of the internal representation
1847 and therefore will never be part of a generated XML record.
1848 Future versions of the Zebra will support that.
1854 SUTRS. Again, the mapping is fairly straightforward. Indentation
1855 is used to show the hierarchical structure of the record. All
1856 "GRS" type records support both the GRS-1 and SUTRS
1858 FIXME - What is SUTRS - should be expanded here
1864 ISO2709-based formats (USMARC, etc.). Only records with a
1865 two-level structure (corresponding to fields and subfields) can be
1866 directly mapped to ISO2709. For records with a different structuring
1867 (eg., GILS), the representation in a structure like USMARC involves a
1868 schema-mapping (see <xref linkend="schema-mapping"/>), to an
1869 "implied" USMARC schema (implied,
1870 because there is no formal schema which specifies the use of the
1871 USMARC fields outside of ISO2709). The resultant, two-level record is
1872 then mapped directly from the internal representation to ISO2709. See
1873 the GILS schema definition files for a detailed example of this
1880 Explain. This representation is only available for records
1881 belonging to the Explain schema.
1887 Summary. This ASN-1 based structure is only available for records
1888 belonging to the Summary schema - or schema which provide a mapping
1889 to this schema (see the description of the schema mapping facility
1896 SOIF. Support for this syntax is experimental, and is currently
1897 keyed to a private Index Data OID (1.2.840.10003.5.1000.81.2). All
1898 abstract syntaxes can be mapped to the SOIF format, although nested
1899 elements are represented by concatenation of the tag names at each
1901 FIXME - Is this used anywhere ? -H
1910 <!-- Keep this comment at the end of the file
1915 sgml-minimize-attributes:nil
1916 sgml-always-quote-attributes:t
1919 sgml-parent-document: "zebra.xml"
1920 sgml-local-catalogs: nil
1921 sgml-namecase-general:t
projects / idzebra-moved-to-github.git / blob