1 <!-- $Id: tools.xml,v 1.30 2003-11-03 09:49:58 mike Exp $ -->
2 <chapter id="tools"><title>Supporting Tools</title>
5 In support of the service API - primarily the ASN module, which
6 provides the pro-grammatic interface to the Z39.50 APDUs, &yaz; contains
7 a collection of tools that support the development of applications.
10 <sect1 id="tools.query"><title>Query Syntax Parsers</title>
13 Since the type-1 (RPN) query structure has no direct, useful string
14 representation, every origin application needs to provide some form of
15 mapping from a local query notation or representation to a
16 <token>Z_RPNQuery</token> structure. Some programmers will prefer to
17 construct the query manually, perhaps using
18 <function>odr_malloc()</function> to simplify memory management.
19 The &yaz; distribution includes three separate, query-generating tools
20 that may be of use to you.
23 <sect2 id="PQF"><title>Prefix Query Format</title>
26 Since RPN or reverse polish notation is really just a fancy way of
27 describing a suffix notation format (operator follows operands), it
28 would seem that the confusion is total when we now introduce a prefix
29 notation for RPN. The reason is one of simple laziness - it's somewhat
30 simpler to interpret a prefix format, and this utility was designed
31 for maximum simplicity, to provide a baseline representation for use
32 in simple test applications and scripting environments (like Tcl). The
33 demonstration client included with YAZ uses the PQF.
38 The PQF have been adopted by other parties developing Z39.50
39 software. It is often referred to as Prefix Query Notation
44 The PQF is defined by the pquery module in the YAZ library.
45 There are two sets of function that have similar behavior. First
46 set operates on a PQF parser handle, second set doesn't. First set
47 set of functions are more flexible than the second set. Second set
48 is obsolete and is only provided to ensure backwards compatibility.
51 First set of functions all operate on a PQF parser handle:
54 #include <yaz/pquery.h>
56 YAZ_PQF_Parser yaz_pqf_create (void);
58 void yaz_pqf_destroy (YAZ_PQF_Parser p);
60 Z_RPNQuery *yaz_pqf_parse (YAZ_PQF_Parser p, ODR o, const char *qbuf);
62 Z_AttributesPlusTerm *yaz_pqf_scan (YAZ_PQF_Parser p, ODR o,
63 Odr_oid **attributeSetId, const char *qbuf);
66 int yaz_pqf_error (YAZ_PQF_Parser p, const char **msg, size_t *off);
69 A PQF parser is created and destructed by functions
70 <function>yaz_pqf_create</function> and
71 <function>yaz_pqf_destroy</function> respectively.
72 Function <function>yaz_pqf_parse</function> parses query given
73 by string <literal>qbuf</literal>. If parsing was successful,
74 a Z39.50 RPN Query is returned which is created using ODR stream
75 <literal>o</literal>. If parsing failed, a NULL pointer is
77 Function <function>yaz_pqf_scan</function> takes a scan query in
78 <literal>qbuf</literal>. If parsing was successful, the function
79 returns attributes plus term pointer and modifies
80 <literal>attributeSetId</literal> to hold attribute set for the
81 scan request - both allocated using ODR stream <literal>o</literal>.
82 If parsing failed, yaz_pqf_scan returns a NULL pointer.
83 Error information for bad queries can be obtained by a call to
84 <function>yaz_pqf_error</function> which returns an error code and
85 modifies <literal>*msg</literal> to point to an error description,
86 and modifies <literal>*off</literal> to the offset within last
87 query were parsing failed.
90 The second set of functions are declared as follows:
93 #include <yaz/pquery.h>
95 Z_RPNQuery *p_query_rpn (ODR o, oid_proto proto, const char *qbuf);
97 Z_AttributesPlusTerm *p_query_scan (ODR o, oid_proto proto,
98 Odr_oid **attributeSetP, const char *qbuf);
100 int p_query_attset (const char *arg);
103 The function <function>p_query_rpn()</function> takes as arguments an
104 &odr; stream (see section <link linkend="odr">The ODR Module</link>)
105 to provide a memory source (the structure created is released on
106 the next call to <function>odr_reset()</function> on the stream), a
107 protocol identifier (one of the constants <token>PROTO_Z3950</token> and
108 <token>PROTO_SR</token>), an attribute set reference, and
109 finally a null-terminated string holding the query string.
112 If the parse went well, <function>p_query_rpn()</function> returns a
113 pointer to a <literal>Z_RPNQuery</literal> structure which can be
114 placed directly into a <literal>Z_SearchRequest</literal>.
115 If parsing failed, due to syntax error, a NULL pointer is returned.
118 The <literal>p_query_attset</literal> specifies which attribute set
119 to use if the query doesn't specify one by the
120 <literal>@attrset</literal> operator.
121 The <literal>p_query_attset</literal> returns 0 if the argument is a
122 valid attribute set specifier; otherwise the function returns -1.
126 The grammar of the PQF is as follows:
130 query ::= top-set query-struct.
132 top-set ::= [ '@attrset' string ]
134 query-struct ::= attr-spec | simple | complex | '@term' term-type query
136 attr-spec ::= '@attr' [ string ] string query-struct
138 complex ::= operator query-struct query-struct.
140 operator ::= '@and' | '@or' | '@not' | '@prox' proximity.
142 simple ::= result-set | term.
144 result-set ::= '@set' string.
148 proximity ::= exclusion distance ordered relation which-code unit-code.
150 exclusion ::= '1' | '0' | 'void'.
152 distance ::= integer.
154 ordered ::= '1' | '0'.
156 relation ::= integer.
158 which-code ::= 'known' | 'private' | integer.
160 unit-code ::= integer.
162 term-type ::= 'general' | 'numeric' | 'string' | 'oid' | 'datetime' | 'null'.
166 You will note that the syntax above is a fairly faithful
167 representation of RPN, except for the Attribute, which has been
168 moved a step away from the term, allowing you to associate one or more
169 attributes with an entire query structure. The parser will
170 automatically apply the given attributes to each term as required.
174 The @attr operator is followed by an attribute specification
175 (<literal>attr-spec</literal> above). The specification consists
176 of an optional attribute set, an attribute type-value pair and
177 a sub-query. The attribute type-value pair is packed in one string:
178 an attribute type, an equals sign, and an attribute value, like this:
179 <literal>@attr 1=1003</literal>.
180 The type is always an integer but the value may be either an
181 integer or a string (if it doesn't start with a digit character).
182 A string attribute-value is encoded as a Type-1 ``complex''
183 attribute with the list of values containing the single string
184 specified, and including no semantic indicators.
188 Version 3 of the Z39.50 specification defines various encoding of terms.
189 Use <literal>@term </literal> <replaceable>type</replaceable>
190 <replaceable>string</replaceable>,
191 where type is one of: <literal>general</literal>,
192 <literal>numeric</literal> or <literal>string</literal>
193 (for InternationalString).
194 If no term type has been given, the <literal>general</literal> form
195 is used. This is the only encoding allowed in both versions 2 and 3
196 of the Z39.50 standard.
199 <sect3 id="PQF-prox">
200 <title>Using Proximity Operators with PQF</title>
203 This is an advanced topic, describing how to construct
204 queries that make very specific requirements on the
205 relative location of their operands.
206 You may wish to skip this section and go straight to
207 <link linkend="pqf-examples">the example PQF queries</link>.
212 Most Z39.50 servers do not support proximity searching, or
213 support only a small subset of the full functionality that
214 can be expressed using the PQF proximity operator. Be
215 aware that the ability to <emphasis>express</emphasis> a
216 query in PQF is no guarantee that any given server will
217 be able to <emphasis>execute</emphasis> it.
223 The proximity operator <literal>@prox</literal> is a special
224 and more restrictive version of the conjunction operator
225 <literal>@and</literal>. Its semantics are described in
226 section 3.7.2 (Proximity) of Z39.50 the standard itself, which
227 can be read on-line at
228 <ulink url="http://lcweb.loc.gov/z3950/agency/markup/09.html"/>
231 In PQF, the proximity operation is represented by a sequence
234 @prox <replaceable>exclusion</replaceable> <replaceable>distance</replaceable> <replaceable>ordered</replaceable> <replaceable>relation</replaceable> <replaceable>which-code</replaceable> <replaceable>unit-code</replaceable>
236 in which the meanings of the parameters are as described in in
237 the standard, and they can take the following values:
239 <listitem><formalpara><title>exclusion</title><para>
240 0 = false (i.e. the proximity condition specified by the
241 remaining parameters must be satisfied) or
242 1 = true (the proximity condition specified by the
243 remaining parameters must <emphasis>not</emphasis> be
245 </para></formalpara></listitem>
246 <listitem><formalpara><title>distance</title><para>
247 An integer specifying the difference between the locations
248 of the operands: e.g. two adjacent words would have
249 distance=1 since their locations differ by one unit.
250 </para></formalpara></listitem>
251 <listitem><formalpara><title>ordered</title><para>
252 1 = ordered (the operands must occur in the order the
253 query specifies them) or
254 0 = unordered (they may appear in either order).
255 </para></formalpara></listitem>
256 <listitem><formalpara><title>relation</title><para>
257 Recognised values are
261 4 (greaterThanOrEqual),
264 </para></formalpara></listitem>
265 <listitem><formalpara><title>which-code</title><para>
266 <literal>known</literal>
269 (the unit-code parameter is taken from the well-known list
270 of alternatives described in below) or
271 <literal>private</literal>
274 (the unit-code paramater has semantics specific to an
275 out-of-band agreement such as a profile).
276 </para></formalpara></listitem>
277 <listitem><formalpara><title>unit-code</title><para>
278 If the which-code parameter is <literal>known</literal>
279 then the recognised values are
291 If which-code is <literal>private</literal> then the
292 acceptable values are determined by the profile.
293 </para></formalpara></listitem>
295 (The numeric values of the relation and well-known unit-code
296 parameters are taken straight from
297 <ulink url="http://lcweb.loc.gov/z3950/agency/asn1.html#ProximityOperator"
298 >the ASN.1</ulink> of the proximity structure in the standard.)
302 <sect3 id="pqf-examples"><title>PQF queries</title>
304 <para>Queries using simple terms.
310 <para>Boolean operators.
312 @or "dylan" "zimmerman"
313 @and @or dylan zimmerman when
314 @and when @or dylan zimmerman
318 Reference to result sets.
325 Attributes for terms.
328 @attr 1=4 @attr 4=1 "self portrait"
329 @attrset exp1 @attr 1=1 CategoryList
330 @attr gils 1=2008 Copenhagen
331 @attr 1=/book/title computer
337 @prox 0 3 1 2 k 2 dylan zimmerman
340 Here the parameters 0, 3, 1, 2, k and 2 represent exclusion,
341 distance, ordered, relation, which-code and unit-code, in that
345 exclusion = 0: the proximity condition must hold
348 distance = 3: the terms must be three units apart
351 ordered = 1: they must occur in the order they are specified
354 relation = 2: lessThanOrEqual (to the distance of 3 units)
357 which-code is ``known'', so the standard unit-codes are used
363 So the whole proximity query means that the words
364 <literal>dylan</literal> and <literal>zimmerman</literal> must
365 both occur in the record, in that order, differing in position
366 by three or fewer words (i.e. with two or fewer words between
367 them.) The query would find ``Bob Dylan, aka. Robert
368 Zimmerman'', but not ``Bob Dylan, born as Robert Zimmerman''
369 since the distance in this case is four.
373 Specifying term type.
375 @term string "a UTF-8 string, maybe?"
380 @or @and bob dylan @set Result-1
382 @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming"
384 @and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109
388 The last of these examples is a spatial search: in
389 <ulink url="http://www.gils.net/prof_v2.html#sec_7_4"
390 >the GILS attribute set</ulink>,
392 2038 indicates West Bounding Coordinate and
393 2030 indicates East Bounding Coordinate,
394 so the query is for areas extending from -114 degrees
395 to no more than -109 degrees.
401 <sect2 id="CCL"><title>CCL</title>
404 Not all users enjoy typing in prefix query structures and numerical
405 attribute values, even in a minimalistic test client. In the library
406 world, the more intuitive Common Command Language - CCL (ISO 8777)
407 has enjoyed some popularity - especially before the widespread
408 availability of graphical interfaces. It is still useful in
409 applications where you for some reason or other need to provide a
410 symbolic language for expressing boolean query structures.
414 The <ulink url="http://europagate.dtv.dk/">EUROPAGATE</ulink>
415 research project working under the Libraries programme
416 of the European Commission's DG XIII has, amongst other useful tools,
417 implemented a general-purpose CCL parser which produces an output
418 structure that can be trivially converted to the internal RPN
419 representation of &yaz; (The <literal>Z_RPNQuery</literal> structure).
420 Since the CCL utility - along with the rest of the software
421 produced by EUROPAGATE - is made freely available on a liberal
422 license, it is included as a supplement to &yaz;.
425 <sect3><title>CCL Syntax</title>
428 The CCL parser obeys the following grammar for the FIND argument.
429 The syntax is annotated by in the lines prefixed by
430 <literal>‐‐</literal>.
434 CCL-Find ::= CCL-Find Op Elements
437 Op ::= "and" | "or" | "not"
438 -- The above means that Elements are separated by boolean operators.
440 Elements ::= '(' CCL-Find ')'
443 | Qualifiers Relation Terms
444 | Qualifiers Relation '(' CCL-Find ')'
445 | Qualifiers '=' string '-' string
446 -- Elements is either a recursive definition, a result set reference, a
447 -- list of terms, qualifiers followed by terms, qualifiers followed
448 -- by a recursive definition or qualifiers in a range (lower - upper).
450 Set ::= 'set' = string
451 -- Reference to a result set
453 Terms ::= Terms Prox Term
455 -- Proximity of terms.
459 -- This basically means that a term may include a blank
461 Qualifiers ::= Qualifiers ',' string
463 -- Qualifiers is a list of strings separated by comma
465 Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<'
466 -- Relational operators. This really doesn't follow the ISO8777
470 -- Proximity operator
474 <example><title>CCL queries</title>
476 The following queries are all valid:
488 (dylan and bob) or set=1
492 Assuming that the qualifiers <literal>ti</literal>,
493 <literal>au</literal>
494 and <literal>date</literal> are defined we may use:
500 au=(bob dylan and slow train coming)
502 date>1980 and (ti=((self portrait)))
508 <sect3><title>CCL Qualifiers</title>
511 Qualifiers are used to direct the search to a particular searchable
512 index, such as title (ti) and author indexes (au). The CCL standard
513 itself doesn't specify a particular set of qualifiers, but it does
514 suggest a few short-hand notations. You can customize the CCL parser
515 to support a particular set of qualifiers to reflect the current target
516 profile. Traditionally, a qualifier would map to a particular
517 use-attribute within the BIB-1 attribute set. It is also
518 possible to set other attributes, such as the structure
523 A CCL profile is a set of predefined CCL qualifiers that may be
524 read from a file or set in the CCL API.
525 The YAZ client reads its CCL qualifiers from a file named
526 <filename>default.bib</filename>. There are four types of
527 lines in a CCL profile: qualifier specification,
528 qualifier alias, comments and directives.
530 <sect4><title id="qualifier-specification">Qualifier specification</title>
532 A qualifier specification is of the form:
536 <replaceable>qualifier-name</replaceable>
537 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable>
538 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable> ...
542 where <replaceable>qualifier-name</replaceable> is the name of the
543 qualifier to be used (eg. <literal>ti</literal>),
544 <replaceable>type</replaceable> is attribute type in the attribute
545 set (Bib-1 is used if no attribute set is given) and
546 <replaceable>val</replaceable> is attribute value.
547 The <replaceable>type</replaceable> can be specified as an
548 integer or as it be specified either as a single-letter:
549 <literal>u</literal> for use,
550 <literal>r</literal> for relation,<literal>p</literal> for position,
551 <literal>s</literal> for structure,<literal>t</literal> for truncation
552 or <literal>c</literal> for completeness.
553 The attributes for the special qualifier name <literal>term</literal>
554 are used when no CCL qualifier is given in a query.
555 <table><title>Common Bib-1 attributes</title>
557 <colspec colwidth="2*" colname="type"></colspec>
558 <colspec colwidth="9*" colname="description"></colspec>
562 <entry>Description</entry>
567 <entry><literal>u=</literal><replaceable>value</replaceable></entry>
569 Use attribute. Common use attributes are
570 1 Personal-name, 4 Title, 7 ISBN, 8 ISSN, 30 Date,
571 62 Subject, 1003 Author), 1016 Any. Specify value
577 <entry><literal>r=</literal><replaceable>value</replaceable></entry>
579 Relation attribute. Common values are
580 1 <, 2 <=, 3 =, 4 >=, 5 >, 6 <>,
581 100 phonetic, 101 stem, 102 relevance, 103 always matches.
586 <entry><literal>p=</literal><replaceable>value</replaceable></entry>
588 Position attribute. Values: 1 first in field, 2
589 first in any subfield, 3 any position in field.
594 <entry><literal>s=</literal><replaceable>value</replaceable></entry>
596 Structure attribute. Values: 1 phrase, 2 word,
597 3 key, 4 year, 5 date, 6 word list, 100 date (un),
598 101 name (norm), 102 name (un), 103 structure, 104 urx,
599 105 free-form-text, 106 document-text, 107 local-number,
600 108 string, 109 numeric string.
605 <entry><literal>t=</literal><replaceable>value</replaceable></entry>
607 Truncation attribute. Values: 1 right, 2 left,
608 3 left& right, 100 none, 101 process #, 102 regular-1,
609 103 regular-2, 104 CCL.
614 <entry><literal>c=</literal><replaceable>value</replaceable></entry>
616 Completeness attribute. Values: 1 incomplete subfield,
617 2 complete subfield, 3 complete field.
626 The complete list of Bib-1 attributes can be found
627 <ulink url="http://lcweb.loc.gov/z3950/agency/defns/bib1.html">
632 It is also possible to specify non-numeric attribute values,
633 which are used in combination with certain types.
634 The special combinations are:
636 <table><title>Special attribute combos</title>
638 <colspec colwidth="2*" colname="name"></colspec>
639 <colspec colwidth="9*" colname="description"></colspec>
643 <entry>Description</entry>
648 <entry><literal>s=pw</literal></entry><entry>
649 The structure is set to either word or phrase depending
650 on the number of tokens in a term (phrase-word).
654 <entry><literal>s=al</literal></entry><entry>
655 Each token in the term is ANDed. (and-list).
656 This does not set the structure at all.
660 <row><entry><literal>s=ol</literal></entry><entry>
661 Each token in the term is ORed. (or-list).
662 This does not set the structure at all.
666 <row><entry><literal>r=o</literal></entry><entry>
667 Allows operators greather-than, less-than, ... equals and
668 sets relation attribute accordingly (relation ordered).
672 <row><entry><literal>t=l</literal></entry><entry>
673 Allows term to be left-truncated.
674 If term is of the form <literal>?x</literal>, the resulting
675 Type-1 term is <literal>x</literal> and truncation is left.
679 <row><entry><literal>t=r</literal></entry><entry>
680 Allows term to be right-truncated.
681 If term is of the form <literal>x?</literal>, the resulting
682 Type-1 term is <literal>x</literal> and truncation is right.
686 <row><entry><literal>t=n</literal></entry><entry>
687 If term is does not include <literal>?</literal>, the
688 truncation attribute is set to none (100).
692 <row><entry><literal>t=b</literal></entry><entry>
693 Allows term to be both left&right truncated.
694 If term is of the form <literal>?x?</literal>, the
695 resulting term is <literal>x</literal> and trunctation is
696 set to both left&right.
703 <example><title>CCL profile</title>
705 Consider the following definition:
716 Four qualifiers are defined - <literal>ti</literal>,
717 <literal>au</literal>, <literal>ranked</literal> and
718 <literal>date</literal>.
721 <literal>ti</literal> and <literal>au</literal> both set
722 structure attribute to phrase (s=1).
723 <literal>ti</literal>
724 sets the use-attribute to 4. <literal>au</literal> sets the
726 When no qualifiers are used in the query the structure-attribute is
727 set to free-form-text (105) (rule for <literal>term</literal>).
728 The <literal>date</literal> sets the relation attribute to
729 the relation used in the CCL query and sets the use attribute
733 You can combine attributes. To Search for "ranked title" you
736 ti,ranked=knuth computer
738 which will set relation=ranked, use=title, structure=phrase.
745 is a valid query, while
753 <sect4><title>Qualifier alias</title>
755 A qualifier alias is of the form:
758 <replaceable>q</replaceable>
759 <replaceable>q1</replaceable> <replaceable>q2</replaceable> ..
762 which declares <replaceable>q</replaceable> to
763 be an alias for <replaceable>q1</replaceable>,
764 <replaceable>q2</replaceable>... such that the CCL
765 query <replaceable>q=x</replaceable> is equivalent to
766 <replaceable>q1=x or w2=x or ...</replaceable>.
770 <sect4><title>Comments</title>
772 Lines with white space or lines that begin with
773 character <literal>#</literal> are treated as comments.
777 <sect4><title>Directives</title>
779 Directive specifications takes the form
781 <para><literal>@</literal><replaceable>directive</replaceable> <replaceable>value</replaceable>
783 <table><title>CCL directives</title>
785 <colspec colwidth="2*" colname="name"></colspec>
786 <colspec colwidth="8*" colname="description"></colspec>
787 <colspec colwidth="1*" colname="default"></colspec>
791 <entry>Description</entry>
792 <entry>Default</entry>
797 <entry>truncation</entry>
798 <entry>Truncation character</entry>
799 <entry><literal>?</literal></entry>
803 <entry>Specifies how multiple fields are to be
804 combined. There are two modes: <literal>or</literal>:
805 multiple qualifier fields are ORed,
806 <literal>merge</literal>: attributes for the qualifier
807 fields are merged and assigned to one term.
809 <entry><literal>merge</literal></entry>
813 <entry>Specificies if CCL operatores and qualifiers should be
814 compared with case sensitivity or not. Specify 0 for
815 case sensitive; 1 for case insensitive.</entry>
816 <entry><literal>0</literal></entry>
821 <entry>Specifies token for CCL operator AND.</entry>
822 <entry><literal>and</literal></entry>
827 <entry>Specifies token for CCL operator OR.</entry>
828 <entry><literal>or</literal></entry>
833 <entry>Specifies token for CCL operator NOT.</entry>
834 <entry><literal>not</literal></entry>
839 <entry>Specifies token for CCL operator SET.</entry>
840 <entry><literal>set</literal></entry>
847 <sect3><title>CCL API</title>
849 All public definitions can be found in the header file
850 <filename>ccl.h</filename>. A profile identifier is of type
851 <literal>CCL_bibset</literal>. A profile must be created with the call
852 to the function <function>ccl_qual_mk</function> which returns a profile
853 handle of type <literal>CCL_bibset</literal>.
857 To read a file containing qualifier definitions the function
858 <function>ccl_qual_file</function> may be convenient. This function
859 takes an already opened <literal>FILE</literal> handle pointer as
860 argument along with a <literal>CCL_bibset</literal> handle.
864 To parse a simple string with a FIND query use the function
867 struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str,
868 int *error, int *pos);
871 which takes the CCL profile (<literal>bibset</literal>) and query
872 (<literal>str</literal>) as input. Upon successful completion the RPN
873 tree is returned. If an error occur, such as a syntax error, the integer
874 pointed to by <literal>error</literal> holds the error code and
875 <literal>pos</literal> holds the offset inside query string in which
880 An English representation of the error may be obtained by calling
881 the <literal>ccl_err_msg</literal> function. The error codes are
882 listed in <filename>ccl.h</filename>.
886 To convert the CCL RPN tree (type
887 <literal>struct ccl_rpn_node *</literal>)
888 to the Z_RPNQuery of YAZ the function <function>ccl_rpn_query</function>
889 must be used. This function which is part of YAZ is implemented in
890 <filename>yaz-ccl.c</filename>.
891 After calling this function the CCL RPN tree is probably no longer
892 needed. The <literal>ccl_rpn_delete</literal> destroys the CCL RPN tree.
896 A CCL profile may be destroyed by calling the
897 <function>ccl_qual_rm</function> function.
901 The token names for the CCL operators may be changed by setting the
902 globals (all type <literal>char *</literal>)
903 <literal>ccl_token_and</literal>, <literal>ccl_token_or</literal>,
904 <literal>ccl_token_not</literal> and <literal>ccl_token_set</literal>.
905 An operator may have aliases, i.e. there may be more than one name for
906 the operator. To do this, separate each alias with a space character.
910 <sect2 id="tools.cql"><title>CQL</title>
912 <ulink url="http://www.loc.gov/z3950/agency/zing/cql/">CQL</ulink>
913 - Common Query Language - was defined for the
914 <ulink url="http://www.loc.gov/z3950/agency/zing/srw/">SRW</ulink>
916 In many ways CQL has a similar syntax to CCL.
917 The objective of CQL is different. Where CCL aims to be
918 an end-user language, CQL is <emphasis>the</emphasis> protocol
919 query language for SRW.
923 If you are new to CQL, read the
924 <ulink url="http://zing.z3950.org/cql/intro.html">Gentle
925 Introduction</ulink>.
929 The CQL parser in &yaz; provides the following:
933 It parses and validates a CQL query.
938 It generates a C structure that allows you to convert
939 a CQL query to some other query language, such as SQL.
944 The parser converts a valid CQL query to PQF, thus providing a
945 way to use CQL for both SRW/SRU servers and Z39.50 targets at the
951 The parser converts CQL to
952 <ulink url="http://www.loc.gov/z3950/agency/zing/cql/xcql.html">
954 XCQL is an XML representation of CQL.
955 XCQL is part of the SRW specification. However, since SRU
956 supports CQL only, we don't expect XCQL to be widely used.
957 Furthermore, CQL has the advantage over XCQL that it is
963 <sect3 id="tools.cql.parsing"><title>CQL parsing</title>
965 A CQL parser is represented by the <literal>CQL_parser</literal>
966 handle. Its contents should be considered &yaz; internal (private).
968 #include <yaz/cql.h>
970 typedef struct cql_parser *CQL_parser;
972 CQL_parser cql_parser_create(void);
973 void cql_parser_destroy(CQL_parser cp);
975 A parser is created by <function>cql_parser_create</function> and
976 is destroyed by <function>cql_parser_destroy</function>.
979 To parse a CQL query string, the following function
982 int cql_parser_string(CQL_parser cp, const char *str);
984 A CQL query is parsed by the <function>cql_parser_string</function>
985 which takes a query <parameter>str</parameter>.
986 If the query was valid (no syntax errors), then zero is returned;
987 otherwise -1 is returned to indicate a syntax error.
991 int cql_parser_stream(CQL_parser cp,
992 int (*getbyte)(void *client_data),
993 void (*ungetbyte)(int b, void *client_data),
996 int cql_parser_stdio(CQL_parser cp, FILE *f);
998 The functions <function>cql_parser_stream</function> and
999 <function>cql_parser_stdio</function> parses a CQL query
1000 - just like <function>cql_parser_string</function>.
1001 The only difference is that the CQL query can be
1002 fed to the parser in different ways.
1003 The <function>cql_parser_stream</function> uses a generic
1004 byte stream as input. The <function>cql_parser_stdio</function>
1005 uses a <literal>FILE</literal> handle which is opened for reading.
1009 <sect3 id="tools.cql.tree"><title>CQL tree</title>
1011 The the query string is valid, the CQL parser
1012 generates a tree representing the structure of the
1017 struct cql_node *cql_parser_result(CQL_parser cp);
1019 <function>cql_parser_result</function> returns the
1020 a pointer to the root node of the resulting tree.
1023 Each node in a CQL tree is represented by a
1024 <literal>struct cql_node</literal>.
1025 It is defined as follows:
1027 #define CQL_NODE_ST 1
1028 #define CQL_NODE_BOOL 2
1029 #define CQL_NODE_MOD 3
1037 struct cql_node *modifiers;
1038 struct cql_node *prefixes;
1042 struct cql_node *left;
1043 struct cql_node *right;
1044 struct cql_node *modifiers;
1045 struct cql_node *prefixes;
1050 struct cql_node *next;
1055 There are three kinds of nodes, search term (ST), boolean (BOOL),
1059 The search term node has five members:
1063 <literal>index</literal>: index for search term.
1064 If an index is unspecified for a search term,
1065 <literal>index</literal> will be NULL.
1070 <literal>term</literal>: the search term itself.
1075 <literal>relation</literal>: relation for search term.
1080 <literal>modifiers</literal>: relation modifiers for search
1081 term. The <literal>modifiers</literal> is a simple linked
1082 list (NULL for last entry). Each relation modifier node
1083 is of type <literal>MOD</literal>.
1088 <literal>prefixes</literal>: index prefixes for search
1089 term. The <literal>prefixes</literal> is a simple linked
1090 list (NULL for last entry). Each prefix node
1091 is of type <literal>MOD</literal>.
1098 The boolean node represents both <literal>and</literal>,
1099 <literal>or</literal>, not as well as
1104 <literal>left</literal> and <literal>right</literal>: left
1105 - and right operand respectively.
1110 <literal>modifiers</literal>: proximity arguments.
1115 <literal>prefixes</literal>: index prefixes.
1116 The <literal>prefixes</literal> is a simple linked
1117 list (NULL for last entry). Each prefix node
1118 is of type <literal>MOD</literal>.
1125 The modifier node is a "utility" node used for name-value pairs,
1126 such as prefixes, proximity arguements, etc.
1130 <literal>name</literal> name of mod node.
1135 <literal>value</literal> value of mod node.
1140 <literal>next</literal>: pointer to next node which is
1141 always a mod node (NULL for last entry).
1148 <sect3 id="tools.cql.pqf"><title>CQL to PQF conversion</title>
1150 Conversion to PQF (and Z39.50 RPN) is tricky by the fact
1151 that the resulting RPN depends on the Z39.50 target
1152 capabilities (combinations of supported attributes).
1153 In addition, the CQL and SRW operates on index prefixes
1154 (URI or strings), whereas the RPN uses Object Identifiers
1158 The CQL library of &yaz; defines a <literal>cql_transform_t</literal>
1159 type. It represents a particular mapping between CQL and RPN.
1160 This handle is created and destroyed by the functions:
1162 cql_transform_t cql_transform_open_FILE (FILE *f);
1163 cql_transform_t cql_transform_open_fname(const char *fname);
1164 void cql_transform_close(cql_transform_t ct);
1166 The first two functions create a tranformation handle from
1167 either an already open FILE or from a filename respectively.
1170 The handle is destroyed by <function>cql_transform_close</function>
1171 in which case no further reference of the handle is allowed.
1174 When a <literal>cql_transform_t</literal> handle has been created
1175 you can convert to RPN.
1177 int cql_transform_buf(cql_transform_t ct,
1178 struct cql_node *cn, char *out, int max);
1180 This function converts the CQL tree <literal>cn</literal>
1181 using handle <literal>ct</literal>.
1182 For the resulting PQF, you supply a buffer <literal>out</literal>
1183 which must be able to hold at at least <literal>max</literal>
1187 If conversion failed, <function>cql_transform_buf</function>
1188 returns a non-zero SRW error code; otherwise zero is returned
1189 (conversion successful). The meanings of the numeric error
1190 codes are listed in the SRW specifications at
1191 <ulink url="http://www.loc.gov/srw/diagnostic-list.html"/>
1194 If conversion fails, more information can be obtained by calling
1196 int cql_transform_error(cql_transform_t ct, char **addinfop);
1198 This function returns the most recently returned numeric
1199 error-code and sets the string-pointer at
1200 <literal>*addinfop</literal> to point to a string containing
1201 additional information about the error that occurred: for
1202 example, if the error code is 15 (``Illegal or unsupported index
1203 set''), the additional information is the name of the requested
1204 index set that was not recognised.
1207 The SRW error-codes may be translated into brief human-readable
1208 error messages using
1210 const char *cql_strerror(int code);
1214 If you wish to be able to produce a PQF result in a different
1215 way, there are two alternatives.
1217 void cql_transform_pr(cql_transform_t ct,
1218 struct cql_node *cn,
1219 void (*pr)(const char *buf, void *client_data),
1222 int cql_transform_FILE(cql_transform_t ct,
1223 struct cql_node *cn, FILE *f);
1225 The former function produces output to a user-defined
1226 output stream. The latter writes the result to an already
1227 open <literal>FILE</literal>.
1230 <sect3 id="tools.cql.map">
1231 <title>Specification of CQL to RPN mapping</title>
1233 The file supplied to functions
1234 <function>cql_transform_open_FILE</function>,
1235 <function>cql_transform_open_fname</function> follows
1236 a structure found in many Unix utilities.
1237 It consists of mapping specifications - one per line.
1238 Lines starting with <literal>#</literal> are ignored (comments).
1241 Each line is of the form
1243 <replaceable>CQL pattern</replaceable><literal> = </literal> <replaceable> RPN equivalent</replaceable>
1247 An RPN pattern is a simple attribute list. Each attribute pair
1250 [<replaceable>set</replaceable>] <replaceable>type</replaceable><literal>=</literal><replaceable>value</replaceable>
1252 The attribute <replaceable>set</replaceable> is optional.
1253 The <replaceable>type</replaceable> is the attribute type,
1254 <replaceable>value</replaceable> the attribute value.
1257 The following CQL patterns are recognized:
1259 <varlistentry><term>
1260 <literal>qualifier.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1264 This pattern is invoked when a CQL qualifier, such as
1265 dc.title is converted. <replaceable>set</replaceable>
1266 and <replaceable>name</replaceable> is the index set and qualifier
1268 Typically, the RPN specifies an equivalent use attribute.
1271 For terms not bound by a qualifier the pattern
1272 <literal>qualifier.srw.serverChoice</literal> is used.
1273 Here, the prefix <literal>srw</literal> is defined as
1274 <literal>http://www.loc.gov/zing/cql/srw-indexes/v1.0/</literal>.
1275 If this pattern is not defined, the mapping will fail.
1279 <varlistentry><term>
1280 <literal>relation.</literal><replaceable>relation</replaceable>
1284 This pattern specifies how a CQL relation is mapped to RPN.
1285 <replaceable>pattern</replaceable> is name of relation
1286 operator. Since <literal>=</literal> is used as
1287 separator between CQL pattern and RPN, CQL relations
1288 including <literal>=</literal> cannot be
1289 used directly. To avoid a conflict, the names
1290 <literal>ge</literal>,
1291 <literal>eq</literal>,
1292 <literal>le</literal>,
1293 must be used for CQL operators, greater-than-or-equal,
1294 equal, less-than-or-equal respectively.
1295 The RPN pattern is supposed to include a relation attribute.
1298 For terms not bound by a relation, the pattern
1299 <literal>relation.scr</literal> is used. If the pattern
1300 is not defined, the mapping will fail.
1303 The special pattern, <literal>relation.*</literal> is used
1304 when no other relation pattern is matched.
1309 <varlistentry><term>
1310 <literal>relationModifier.</literal><replaceable>mod</replaceable>
1314 This pattern specifies how a CQL relation modifier is mapped to RPN.
1315 The RPN pattern is usually a relation attribute.
1320 <varlistentry><term>
1321 <literal>structure.</literal><replaceable>type</replaceable>
1325 This pattern specifies how a CQL structure is mapped to RPN.
1326 Note that this CQL pattern is somewhat to similar to
1327 CQL pattern <literal>relation</literal>.
1328 The <replaceable>type</replaceable> is a CQL relation.
1331 The pattern, <literal>structure.*</literal> is used
1332 when no other structure pattern is matched.
1333 Usually, the RPN equivalent specifies a structure attribute.
1338 <varlistentry><term>
1339 <literal>position.</literal><replaceable>type</replaceable>
1343 This pattern specifies how the anchor (position) of
1344 CQL is mapped to RPN.
1345 The <replaceable>type</replaceable> is one
1346 of <literal>first</literal>, <literal>any</literal>,
1347 <literal>last</literal>, <literal>firstAndLast</literal>.
1350 The pattern, <literal>position.*</literal> is used
1351 when no other position pattern is matched.
1356 <varlistentry><term>
1357 <literal>set.</literal><replaceable>prefix</replaceable>
1361 This specification defines a CQL index set for a given prefix.
1362 The value on the right hand side is the URI for the set -
1363 <emphasis>not</emphasis> RPN. All prefixes used in
1364 qualifier patterns must be defined this way.
1370 <example><title>CQL to RPN mapping file</title>
1372 This simple file defines two index sets, three qualifiers and three
1373 relations, a position pattern and a default structure.
1375 <programlisting><![CDATA[
1376 set.srw = http://www.loc.gov/zing/cql/srw-indexes/v1.0/
1377 set.dc = http://www.loc.gov/zing/cql/dc-indexes/v1.0/
1379 qualifier.srw.serverChoice = 1=1016
1380 qualifier.dc.title = 1=4
1381 qualifier.dc.subject = 1=21
1387 position.any = 3=3 6=1
1393 With the mappings above, the CQL query
1397 is converted to the PQF:
1399 @attr 1=1016 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "computer"
1401 by rules <literal>qualifier.srw.serverChoice</literal>,
1402 <literal>relation.scr</literal>, <literal>structure.*</literal>,
1403 <literal>position.any</literal>.
1410 is rejected, since <literal>position.right</literal> is
1416 >my = "http://www.loc.gov/zing/cql/dc-indexes/v1.0/" my.title = x
1420 @attr 1=4 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "x"
1425 <sect3 id="tools.cql.xcql"><title>CQL to XCQL conversion</title>
1427 Conversion from CQL to XCQL is trivial and does not
1428 require a mapping to be defined.
1429 There three functions to choose from depending on the
1430 way you wish to store the resulting output (XML buffer
1433 int cql_to_xml_buf(struct cql_node *cn, char *out, int max);
1434 void cql_to_xml(struct cql_node *cn,
1435 void (*pr)(const char *buf, void *client_data),
1437 void cql_to_xml_stdio(struct cql_node *cn, FILE *f);
1439 Function <function>cql_to_xml_buf</function> converts
1440 to XCQL and stores result in a user supplied buffer of a given
1444 <function>cql_to_xml</function> writes the result in
1445 a user defined output stream.
1446 <function>cql_to_xml_stdio</function> writes to a
1452 <sect1 id="tools.oid"><title>Object Identifiers</title>
1455 The basic YAZ representation of an OID is an array of integers,
1456 terminated with the value -1. The &odr; module provides two
1457 utility-functions to create and copy this type of data elements:
1461 Odr_oid *odr_getoidbystr(ODR o, char *str);
1465 Creates an OID based on a string-based representation using dots (.)
1466 to separate elements in the OID.
1470 Odr_oid *odr_oiddup(ODR odr, Odr_oid *o);
1474 Creates a copy of the OID referenced by the <emphasis>o</emphasis>
1476 Both functions take an &odr; stream as parameter. This stream is used to
1477 allocate memory for the data elements, which is released on a
1478 subsequent call to <function>odr_reset()</function> on that stream.
1482 The OID module provides a higher-level representation of the
1483 family of object identifiers which describe the Z39.50 protocol and its
1484 related objects. The definition of the module interface is given in
1485 the <filename>oid.h</filename> file.
1489 The interface is mainly based on the <literal>oident</literal> structure.
1490 The definition of this structure looks like this:
1494 typedef struct oident
1499 int oidsuffix[OID_SIZE];
1505 The proto field takes one of the values
1514 Use <literal>PROTO_Z3950</literal> for Z39.50 Object Identifers,
1515 <literal>PROTO_GENERAL</literal> for other types (such as
1516 those associated with ILL).
1520 The oclass field takes one of the values
1542 corresponding to the OID classes defined by the Z39.50 standard.
1544 Finally, the value field takes one of the values
1602 again, corresponding to the specific OIDs defined by the standard.
1604 <ulink url="http://lcweb.loc.gov/z3950/agency/defns/oids.html">
1605 Registry of Z39.50 Object Identifiers</ulink> for the
1610 The desc field contains a brief, mnemonic name for the OID in question.
1618 struct oident *oid_getentbyoid(int *o);
1622 takes as argument an OID, and returns a pointer to a static area
1623 containing an <literal>oident</literal> structure. You typically use
1624 this function when you receive a PDU containing an OID, and you wish
1625 to branch out depending on the specific OID value.
1633 int *oid_ent_to_oid(struct oident *ent, int *dst);
1637 Takes as argument an <literal>oident</literal> structure - in which
1638 the <literal>proto</literal>, <literal>oclass</literal>/, and
1639 <literal>value</literal> fields are assumed to be set correctly -
1640 and returns a pointer to a the buffer as given by <literal>dst</literal>
1642 representation of the corresponding OID. The function returns
1643 NULL and the array dst is unchanged if a mapping couldn't place.
1644 The array <literal>dst</literal> should be at least of size
1645 <literal>OID_SIZE</literal>.
1649 The <function>oid_ent_to_oid()</function> function can be used whenever
1650 you need to prepare a PDU containing one or more OIDs. The separation of
1651 the <literal>protocol</literal> element from the remainder of the
1652 OID-description makes it simple to write applications that can
1653 communicate with either Z39.50 or OSI SR-based applications.
1661 oid_value oid_getvalbyname(const char *name);
1665 takes as argument a mnemonic OID name, and returns the
1666 <literal>/value</literal> field of the first entry in the database that
1667 contains the given name in its <literal>desc</literal> field.
1671 Three utility functions are provided for translating OIDs'
1672 symbolic names (e.g. <literal>Usmarc</literal> into OID structures
1673 (int arrays) and strings containing the OID in dotted notation
1674 (e.g. <literal>1.2.840.10003.9.5.1</literal>). They are:
1678 int *oid_name_to_oid(oid_class oclass, const char *name, int *oid);
1679 char *oid_to_dotstring(const int *oid, char *oidbuf);
1680 char *oid_name_to_dotstring(oid_class oclass, const char *name, char *oidbuf);
1684 <literal>oid_name_to_oid()</literal>
1685 translates the specified symbolic <literal>name</literal>,
1686 interpreted as being of class <literal>oclass</literal>. (The
1687 class must be specified as many symbolic names exist within
1688 multiple classes - for example, <literal>Zthes</literal> is the
1689 symbolic name of an attribute set, a schema and a tag-set.) The
1690 sequence of integers representing the OID is written into the
1691 area <literal>oid</literal> provided by the caller; it is the
1692 caller's responsibility to ensure that this area is large enough
1693 to contain the translated OID. As a convenience, the address of
1694 the buffer (i.e. the value of <literal>oid</literal>) is
1698 <literal>oid_to_dotstring()</literal>
1699 Translates the int-array <literal>oid</literal> into a dotted
1700 string which is written into the area <literal>oidbuf</literal>
1701 supplied by the caller; it is the caller's responsibility to
1702 ensure that this area is large enough. The address of the buffer
1706 <literal>oid_name_to_dotstring()</literal>
1707 combines the previous two functions to derive a dotted string
1708 representing the OID specified by <literal>oclass</literal> and
1709 <literal>name</literal>, writing it into the buffer passed as
1710 <literal>oidbuf</literal> and returning its address.
1714 Finally, the module provides the following utility functions, whose
1715 meaning should be obvious:
1719 void oid_oidcpy(int *t, int *s);
1720 void oid_oidcat(int *t, int *s);
1721 int oid_oidcmp(int *o1, int *o2);
1722 int oid_oidlen(int *o);
1727 The OID module has been criticized - and perhaps rightly so
1728 - for needlessly abstracting the
1729 representation of OIDs. Other toolkits use a simple
1730 string-representation of OIDs with good results. In practice, we have
1731 found the interface comfortable and quick to work with, and it is a
1732 simple matter (for what it's worth) to create applications compatible
1733 with both ISO SR and Z39.50. Finally, the use of the
1734 <literal>/oident</literal> database is by no means mandatory.
1735 You can easily create your own system for representing OIDs, as long
1736 as it is compatible with the low-level integer-array representation
1743 <sect1 id="tools.nmem"><title>Nibble Memory</title>
1746 Sometimes when you need to allocate and construct a large,
1747 interconnected complex of structures, it can be a bit of a pain to
1748 release the associated memory again. For the structures describing the
1749 Z39.50 PDUs and related structures, it is convenient to use the
1750 memory-management system of the &odr; subsystem (see
1751 <link linkend="odr-use">Using ODR</link>). However, in some circumstances
1752 where you might otherwise benefit from using a simple nibble memory
1753 management system, it may be impractical to use
1754 <function>odr_malloc()</function> and <function>odr_reset()</function>.
1755 For this purpose, the memory manager which also supports the &odr;
1756 streams is made available in the NMEM module. The external interface
1757 to this module is given in the <filename>nmem.h</filename> file.
1761 The following prototypes are given:
1765 NMEM nmem_create(void);
1766 void nmem_destroy(NMEM n);
1767 void *nmem_malloc(NMEM n, int size);
1768 void nmem_reset(NMEM n);
1769 int nmem_total(NMEM n);
1770 void nmem_init(void);
1771 void nmem_exit(void);
1775 The <function>nmem_create()</function> function returns a pointer to a
1776 memory control handle, which can be released again by
1777 <function>nmem_destroy()</function> when no longer needed.
1778 The function <function>nmem_malloc()</function> allocates a block of
1779 memory of the requested size. A call to <function>nmem_reset()</function>
1780 or <function>nmem_destroy()</function> will release all memory allocated
1781 on the handle since it was created (or since the last call to
1782 <function>nmem_reset()</function>. The function
1783 <function>nmem_total()</function> returns the number of bytes currently
1784 allocated on the handle.
1788 The nibble memory pool is shared amongst threads. POSIX
1789 mutex'es and WIN32 Critical sections are introduced to keep the
1790 module thread safe. Function <function>nmem_init()</function>
1791 initializes the nibble memory library and it is called automatically
1792 the first time the <literal>YAZ.DLL</literal> is loaded. &yaz; uses
1793 function <function>DllMain</function> to achieve this. You should
1794 <emphasis>not</emphasis> call <function>nmem_init</function> or
1795 <function>nmem_exit</function> unless you're absolute sure what
1796 you're doing. Note that in previous &yaz; versions you'd have to call
1797 <function>nmem_init</function> yourself.
1803 <!-- Keep this comment at the end of the file
1808 sgml-minimize-attributes:nil
1809 sgml-always-quote-attributes:t
1812 sgml-parent-document: "yaz.xml"
1813 sgml-local-catalogs: nil
1814 sgml-namecase-general:t