1 <!-- $Id: tools.xml,v 1.29 2003-11-03 09:34:02 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48 is obsolete and is only provided to ensure backwards compatibility.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 optional an 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, a dash, followed by an attribute value.
179 The type is always an integer but the value may be either an
180 integer or a string (if it doesn't start with a digit character).
184 Version 3 of the Z39.50 specification defines various encoding of terms.
185 Use <literal>@term </literal> <replaceable>type</replaceable>
186 <replaceable>string</replaceable>,
187 where type is one of: <literal>general</literal>,
188 <literal>numeric</literal> or <literal>string</literal>
189 (for InternationalString).
190 If no term type has been given, the <literal>general</literal> form
191 is used. This is the only encoding allowed in both versions 2 and 3
192 of the Z39.50 standard.
195 <sect3 id="PQF-prox">
196 <title>Using Proximity Operators with PQF</title>
199 This is an advanced topic, describing how to construct
200 queries that make very specific requirements on the
201 relative location of their operands.
202 You may wish to skip this section and go straight to
203 <link linkend="pqf-examples">the example PQF queries</link>.
208 Most Z39.50 servers do not support proximity searching, or
209 support only a small subset of the full functionality that
210 can be expressed using the PQF proximity operator. Be
211 aware that the ability to <emphasis>express</emphasis> a
212 query in PQF is no guarantee that any given server will
213 be able to <emphasis>execute</emphasis> it.
219 The proximity operator <literal>@prox</literal> is a special
220 and more restrictive version of the conjunction operator
221 <literal>@and</literal>. Its semantics are described in
222 section 3.7.2 (Proximity) of Z39.50 the standard itself, which
223 can be read on-line at
224 <ulink url="http://lcweb.loc.gov/z3950/agency/markup/09.html"/>
227 In PQF, the proximity operation is represented by a sequence
230 @prox <replaceable>exclusion</replaceable> <replaceable>distance</replaceable> <replaceable>ordered</replaceable> <replaceable>relation</replaceable> <replaceable>which-code</replaceable> <replaceable>unit-code</replaceable>
232 in which the meanings of the parameters are as described in in
233 the standard, and they can take the following values:
235 <listitem><formalpara><title>exclusion</title><para>
236 0 = false (i.e. the proximity condition specified by the
237 remaining parameters must be satisfied) or
238 1 = true (the proximity condition specified by the
239 remaining parameters must <emphasis>not</emphasis> be
241 </para></formalpara></listitem>
242 <listitem><formalpara><title>distance</title><para>
243 An integer specifying the difference between the locations
244 of the operands: e.g. two adjacent words would have
245 distance=1 since their locations differ by one unit.
246 </para></formalpara></listitem>
247 <listitem><formalpara><title>ordered</title><para>
248 1 = ordered (the operands must occur in the order the
249 query specifies them) or
250 0 = unordered (they may appear in either order).
251 </para></formalpara></listitem>
252 <listitem><formalpara><title>relation</title><para>
253 Recognised values are
257 4 (greaterThanOrEqual),
260 </para></formalpara></listitem>
261 <listitem><formalpara><title>which-code</title><para>
262 <literal>known</literal>
265 (the unit-code parameter is taken from the well-known list
266 of alternatives described in below) or
267 <literal>private</literal>
270 (the unit-code paramater has semantics specific to an
271 out-of-band agreement such as a profile).
272 </para></formalpara></listitem>
273 <listitem><formalpara><title>unit-code</title><para>
274 If the which-code parameter is <literal>known</literal>
275 then the recognised values are
287 If which-code is <literal>private</literal> then the
288 acceptable values are determined by the profile.
289 </para></formalpara></listitem>
291 (The numeric values of the relation and well-known unit-code
292 parameters are taken straight from
293 <ulink url="http://lcweb.loc.gov/z3950/agency/asn1.html#ProximityOperator"
294 >the ASN.1</ulink> of the proximity structure in the standard.)
298 <sect3 id="pqf-examples"><title>PQF queries</title>
300 <para>Queries using simple terms.
306 <para>Boolean operators.
308 @or "dylan" "zimmerman"
309 @and @or dylan zimmerman when
310 @and when @or dylan zimmerman
314 Reference to result sets.
321 Attributes for terms.
324 @attr 1=4 @attr 4=1 "self portrait"
325 @attrset exp1 @attr 1=1 CategoryList
326 @attr gils 1=2008 Copenhagen
327 @attr 1=/book/title computer
333 @prox 0 3 1 2 k 2 dylan zimmerman
336 Here the parameters 0, 3, 1, 2, k and 2 represent exclusion,
337 distance, ordered, relation, which-code and unit-code, in that
341 exclusion = 0: the proximity condition must hold
344 distance = 3: the terms must be three units apart
347 ordered = 1: they must occur in the order they are specified
350 relation = 2: lessThanOrEqual (to the distance of 3 units)
353 which-code is ``known'', so the standard unit-codes are used
359 So the whole proximity query means that the words
360 <literal>dylan</literal> and <literal>zimmerman</literal> must
361 both occur in the record, in that order, differing in position
362 by three or fewer words (i.e. with two or fewer words between
363 them.) The query would find ``Bob Dylan, aka. Robert
364 Zimmerman'', but not ``Bob Dylan, born as Robert Zimmerman''
365 since the distance in this case is four.
369 Specifying term type.
371 @term string "a UTF-8 string, maybe?"
376 @or @and bob dylan @set Result-1
378 @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming"
380 @and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109
384 The last of these examples is a spatial search: in
385 <ulink url="http://www.gils.net/prof_v2.html#sec_7_4"
386 >the GILS attribute set</ulink>,
388 2038 indicates West Bounding Coordinate and
389 2030 indicates East Bounding Coordinate,
390 so the query is for areas extending from -114 degrees
391 to no more than -109 degrees.
397 <sect2 id="CCL"><title>CCL</title>
400 Not all users enjoy typing in prefix query structures and numerical
401 attribute values, even in a minimalistic test client. In the library
402 world, the more intuitive Common Command Language - CCL (ISO 8777)
403 has enjoyed some popularity - especially before the widespread
404 availability of graphical interfaces. It is still useful in
405 applications where you for some reason or other need to provide a
406 symbolic language for expressing boolean query structures.
410 The <ulink url="http://europagate.dtv.dk/">EUROPAGATE</ulink>
411 research project working under the Libraries programme
412 of the European Commission's DG XIII has, amongst other useful tools,
413 implemented a general-purpose CCL parser which produces an output
414 structure that can be trivially converted to the internal RPN
415 representation of &yaz; (The <literal>Z_RPNQuery</literal> structure).
416 Since the CCL utility - along with the rest of the software
417 produced by EUROPAGATE - is made freely available on a liberal
418 license, it is included as a supplement to &yaz;.
421 <sect3><title>CCL Syntax</title>
424 The CCL parser obeys the following grammar for the FIND argument.
425 The syntax is annotated by in the lines prefixed by
426 <literal>‐‐</literal>.
430 CCL-Find ::= CCL-Find Op Elements
433 Op ::= "and" | "or" | "not"
434 -- The above means that Elements are separated by boolean operators.
436 Elements ::= '(' CCL-Find ')'
439 | Qualifiers Relation Terms
440 | Qualifiers Relation '(' CCL-Find ')'
441 | Qualifiers '=' string '-' string
442 -- Elements is either a recursive definition, a result set reference, a
443 -- list of terms, qualifiers followed by terms, qualifiers followed
444 -- by a recursive definition or qualifiers in a range (lower - upper).
446 Set ::= 'set' = string
447 -- Reference to a result set
449 Terms ::= Terms Prox Term
451 -- Proximity of terms.
455 -- This basically means that a term may include a blank
457 Qualifiers ::= Qualifiers ',' string
459 -- Qualifiers is a list of strings separated by comma
461 Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<'
462 -- Relational operators. This really doesn't follow the ISO8777
466 -- Proximity operator
470 <example><title>CCL queries</title>
472 The following queries are all valid:
484 (dylan and bob) or set=1
488 Assuming that the qualifiers <literal>ti</literal>,
489 <literal>au</literal>
490 and <literal>date</literal> are defined we may use:
496 au=(bob dylan and slow train coming)
498 date>1980 and (ti=((self portrait)))
504 <sect3><title>CCL Qualifiers</title>
507 Qualifiers are used to direct the search to a particular searchable
508 index, such as title (ti) and author indexes (au). The CCL standard
509 itself doesn't specify a particular set of qualifiers, but it does
510 suggest a few short-hand notations. You can customize the CCL parser
511 to support a particular set of qualifiers to reflect the current target
512 profile. Traditionally, a qualifier would map to a particular
513 use-attribute within the BIB-1 attribute set. It is also
514 possible to set other attributes, such as the structure
519 A CCL profile is a set of predefined CCL qualifiers that may be
520 read from a file or set in the CCL API.
521 The YAZ client reads its CCL qualifiers from a file named
522 <filename>default.bib</filename>. There are four types of
523 lines in a CCL profile: qualifier specification,
524 qualifier alias, comments and directives.
526 <sect4><title id="qualifier-specification">Qualifier specification</title>
528 A qualifier specification is of the form:
532 <replaceable>qualifier-name</replaceable>
533 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable>
534 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable> ...
538 where <replaceable>qualifier-name</replaceable> is the name of the
539 qualifier to be used (eg. <literal>ti</literal>),
540 <replaceable>type</replaceable> is attribute type in the attribute
541 set (Bib-1 is used if no attribute set is given) and
542 <replaceable>val</replaceable> is attribute value.
543 The <replaceable>type</replaceable> can be specified as an
544 integer or as it be specified either as a single-letter:
545 <literal>u</literal> for use,
546 <literal>r</literal> for relation,<literal>p</literal> for position,
547 <literal>s</literal> for structure,<literal>t</literal> for truncation
548 or <literal>c</literal> for completeness.
549 The attributes for the special qualifier name <literal>term</literal>
550 are used when no CCL qualifier is given in a query.
551 <table><title>Common Bib-1 attributes</title>
553 <colspec colwidth="2*" colname="type"></colspec>
554 <colspec colwidth="9*" colname="description"></colspec>
558 <entry>Description</entry>
563 <entry><literal>u=</literal><replaceable>value</replaceable></entry>
565 Use attribute. Common use attributes are
566 1 Personal-name, 4 Title, 7 ISBN, 8 ISSN, 30 Date,
567 62 Subject, 1003 Author), 1016 Any. Specify value
573 <entry><literal>r=</literal><replaceable>value</replaceable></entry>
575 Relation attribute. Common values are
576 1 <, 2 <=, 3 =, 4 >=, 5 >, 6 <>,
577 100 phonetic, 101 stem, 102 relevance, 103 always matches.
582 <entry><literal>p=</literal><replaceable>value</replaceable></entry>
584 Position attribute. Values: 1 first in field, 2
585 first in any subfield, 3 any position in field.
590 <entry><literal>s=</literal><replaceable>value</replaceable></entry>
592 Structure attribute. Values: 1 phrase, 2 word,
593 3 key, 4 year, 5 date, 6 word list, 100 date (un),
594 101 name (norm), 102 name (un), 103 structure, 104 urx,
595 105 free-form-text, 106 document-text, 107 local-number,
596 108 string, 109 numeric string.
601 <entry><literal>t=</literal><replaceable>value</replaceable></entry>
603 Truncation attribute. Values: 1 right, 2 left,
604 3 left& right, 100 none, 101 process #, 102 regular-1,
605 103 regular-2, 104 CCL.
610 <entry><literal>c=</literal><replaceable>value</replaceable></entry>
612 Completeness attribute. Values: 1 incomplete subfield,
613 2 complete subfield, 3 complete field.
622 The complete list of Bib-1 attributes can be found
623 <ulink url="http://lcweb.loc.gov/z3950/agency/defns/bib1.html">
628 It is also possible to specify non-numeric attribute values,
629 which are used in combination with certain types.
630 The special combinations are:
632 <table><title>Special attribute combos</title>
634 <colspec colwidth="2*" colname="name"></colspec>
635 <colspec colwidth="9*" colname="description"></colspec>
639 <entry>Description</entry>
644 <entry><literal>s=pw</literal></entry><entry>
645 The structure is set to either word or phrase depending
646 on the number of tokens in a term (phrase-word).
650 <entry><literal>s=al</literal></entry><entry>
651 Each token in the term is ANDed. (and-list).
652 This does not set the structure at all.
656 <row><entry><literal>s=ol</literal></entry><entry>
657 Each token in the term is ORed. (or-list).
658 This does not set the structure at all.
662 <row><entry><literal>r=o</literal></entry><entry>
663 Allows operators greather-than, less-than, ... equals and
664 sets relation attribute accordingly (relation ordered).
668 <row><entry><literal>t=l</literal></entry><entry>
669 Allows term to be left-truncated.
670 If term is of the form <literal>?x</literal>, the resulting
671 Type-1 term is <literal>x</literal> and truncation is left.
675 <row><entry><literal>t=r</literal></entry><entry>
676 Allows term to be right-truncated.
677 If term is of the form <literal>x?</literal>, the resulting
678 Type-1 term is <literal>x</literal> and truncation is right.
682 <row><entry><literal>t=n</literal></entry><entry>
683 If term is does not include <literal>?</literal>, the
684 truncation attribute is set to none (100).
688 <row><entry><literal>t=b</literal></entry><entry>
689 Allows term to be both left&right truncated.
690 If term is of the form <literal>?x?</literal>, the
691 resulting term is <literal>x</literal> and trunctation is
692 set to both left&right.
699 <example><title>CCL profile</title>
701 Consider the following definition:
712 Four qualifiers are defined - <literal>ti</literal>,
713 <literal>au</literal>, <literal>ranked</literal> and
714 <literal>date</literal>.
717 <literal>ti</literal> and <literal>au</literal> both set
718 structure attribute to phrase (s=1).
719 <literal>ti</literal>
720 sets the use-attribute to 4. <literal>au</literal> sets the
722 When no qualifiers are used in the query the structure-attribute is
723 set to free-form-text (105) (rule for <literal>term</literal>).
724 The <literal>date</literal> sets the relation attribute to
725 the relation used in the CCL query and sets the use attribute
729 You can combine attributes. To Search for "ranked title" you
732 ti,ranked=knuth computer
734 which will set relation=ranked, use=title, structure=phrase.
741 is a valid query, while
749 <sect4><title>Qualifier alias</title>
751 A qualifier alias is of the form:
754 <replaceable>q</replaceable>
755 <replaceable>q1</replaceable> <replaceable>q2</replaceable> ..
758 which declares <replaceable>q</replaceable> to
759 be an alias for <replaceable>q1</replaceable>,
760 <replaceable>q2</replaceable>... such that the CCL
761 query <replaceable>q=x</replaceable> is equivalent to
762 <replaceable>q1=x or w2=x or ...</replaceable>.
766 <sect4><title>Comments</title>
768 Lines with white space or lines that begin with
769 character <literal>#</literal> are treated as comments.
773 <sect4><title>Directives</title>
775 Directive specifications takes the form
777 <para><literal>@</literal><replaceable>directive</replaceable> <replaceable>value</replaceable>
779 <table><title>CCL directives</title>
781 <colspec colwidth="2*" colname="name"></colspec>
782 <colspec colwidth="8*" colname="description"></colspec>
783 <colspec colwidth="1*" colname="default"></colspec>
787 <entry>Description</entry>
788 <entry>Default</entry>
793 <entry>truncation</entry>
794 <entry>Truncation character</entry>
795 <entry><literal>?</literal></entry>
799 <entry>Specifies how multiple fields are to be
800 combined. There are two modes: <literal>or</literal>:
801 multiple qualifier fields are ORed,
802 <literal>merge</literal>: attributes for the qualifier
803 fields are merged and assigned to one term.
805 <entry><literal>merge</literal></entry>
809 <entry>Specificies if CCL operatores and qualifiers should be
810 compared with case sensitivity or not. Specify 0 for
811 case sensitive; 1 for case insensitive.</entry>
812 <entry><literal>0</literal></entry>
817 <entry>Specifies token for CCL operator AND.</entry>
818 <entry><literal>and</literal></entry>
823 <entry>Specifies token for CCL operator OR.</entry>
824 <entry><literal>or</literal></entry>
829 <entry>Specifies token for CCL operator NOT.</entry>
830 <entry><literal>not</literal></entry>
835 <entry>Specifies token for CCL operator SET.</entry>
836 <entry><literal>set</literal></entry>
843 <sect3><title>CCL API</title>
845 All public definitions can be found in the header file
846 <filename>ccl.h</filename>. A profile identifier is of type
847 <literal>CCL_bibset</literal>. A profile must be created with the call
848 to the function <function>ccl_qual_mk</function> which returns a profile
849 handle of type <literal>CCL_bibset</literal>.
853 To read a file containing qualifier definitions the function
854 <function>ccl_qual_file</function> may be convenient. This function
855 takes an already opened <literal>FILE</literal> handle pointer as
856 argument along with a <literal>CCL_bibset</literal> handle.
860 To parse a simple string with a FIND query use the function
863 struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str,
864 int *error, int *pos);
867 which takes the CCL profile (<literal>bibset</literal>) and query
868 (<literal>str</literal>) as input. Upon successful completion the RPN
869 tree is returned. If an error occur, such as a syntax error, the integer
870 pointed to by <literal>error</literal> holds the error code and
871 <literal>pos</literal> holds the offset inside query string in which
876 An English representation of the error may be obtained by calling
877 the <literal>ccl_err_msg</literal> function. The error codes are
878 listed in <filename>ccl.h</filename>.
882 To convert the CCL RPN tree (type
883 <literal>struct ccl_rpn_node *</literal>)
884 to the Z_RPNQuery of YAZ the function <function>ccl_rpn_query</function>
885 must be used. This function which is part of YAZ is implemented in
886 <filename>yaz-ccl.c</filename>.
887 After calling this function the CCL RPN tree is probably no longer
888 needed. The <literal>ccl_rpn_delete</literal> destroys the CCL RPN tree.
892 A CCL profile may be destroyed by calling the
893 <function>ccl_qual_rm</function> function.
897 The token names for the CCL operators may be changed by setting the
898 globals (all type <literal>char *</literal>)
899 <literal>ccl_token_and</literal>, <literal>ccl_token_or</literal>,
900 <literal>ccl_token_not</literal> and <literal>ccl_token_set</literal>.
901 An operator may have aliases, i.e. there may be more than one name for
902 the operator. To do this, separate each alias with a space character.
906 <sect2 id="tools.cql"><title>CQL</title>
908 <ulink url="http://www.loc.gov/z3950/agency/zing/cql/">CQL</ulink>
909 - Common Query Language - was defined for the
910 <ulink url="http://www.loc.gov/z3950/agency/zing/srw/">SRW</ulink>
912 In many ways CQL has a similar syntax to CCL.
913 The objective of CQL is different. Where CCL aims to be
914 an end-user language, CQL is <emphasis>the</emphasis> protocol
915 query language for SRW.
919 If you are new to CQL, read the
920 <ulink url="http://zing.z3950.org/cql/intro.html">Gentle
921 Introduction</ulink>.
925 The CQL parser in &yaz; provides the following:
929 It parses and validates a CQL query.
934 It generates a C structure that allows you to convert
935 a CQL query to some other query language, such as SQL.
940 The parser converts a valid CQL query to PQF, thus providing a
941 way to use CQL for both SRW/SRU servers and Z39.50 targets at the
947 The parser converts CQL to
948 <ulink url="http://www.loc.gov/z3950/agency/zing/cql/xcql.html">
950 XCQL is an XML representation of CQL.
951 XCQL is part of the SRW specification. However, since SRU
952 supports CQL only, we don't expect XCQL to be widely used.
953 Furthermore, CQL has the advantage over XCQL that it is
959 <sect3 id="tools.cql.parsing"><title>CQL parsing</title>
961 A CQL parser is represented by the <literal>CQL_parser</literal>
962 handle. Its contents should be considered &yaz; internal (private).
964 #include <yaz/cql.h>
966 typedef struct cql_parser *CQL_parser;
968 CQL_parser cql_parser_create(void);
969 void cql_parser_destroy(CQL_parser cp);
971 A parser is created by <function>cql_parser_create</function> and
972 is destroyed by <function>cql_parser_destroy</function>.
975 To parse a CQL query string, the following function
978 int cql_parser_string(CQL_parser cp, const char *str);
980 A CQL query is parsed by the <function>cql_parser_string</function>
981 which takes a query <parameter>str</parameter>.
982 If the query was valid (no syntax errors), then zero is returned;
983 otherwise -1 is returned to indicate a syntax error.
987 int cql_parser_stream(CQL_parser cp,
988 int (*getbyte)(void *client_data),
989 void (*ungetbyte)(int b, void *client_data),
992 int cql_parser_stdio(CQL_parser cp, FILE *f);
994 The functions <function>cql_parser_stream</function> and
995 <function>cql_parser_stdio</function> parses a CQL query
996 - just like <function>cql_parser_string</function>.
997 The only difference is that the CQL query can be
998 fed to the parser in different ways.
999 The <function>cql_parser_stream</function> uses a generic
1000 byte stream as input. The <function>cql_parser_stdio</function>
1001 uses a <literal>FILE</literal> handle which is opened for reading.
1005 <sect3 id="tools.cql.tree"><title>CQL tree</title>
1007 The the query string is valid, the CQL parser
1008 generates a tree representing the structure of the
1013 struct cql_node *cql_parser_result(CQL_parser cp);
1015 <function>cql_parser_result</function> returns the
1016 a pointer to the root node of the resulting tree.
1019 Each node in a CQL tree is represented by a
1020 <literal>struct cql_node</literal>.
1021 It is defined as follows:
1023 #define CQL_NODE_ST 1
1024 #define CQL_NODE_BOOL 2
1025 #define CQL_NODE_MOD 3
1033 struct cql_node *modifiers;
1034 struct cql_node *prefixes;
1038 struct cql_node *left;
1039 struct cql_node *right;
1040 struct cql_node *modifiers;
1041 struct cql_node *prefixes;
1046 struct cql_node *next;
1051 There are three kinds of nodes, search term (ST), boolean (BOOL),
1055 The search term node has five members:
1059 <literal>index</literal>: index for search term.
1060 If an index is unspecified for a search term,
1061 <literal>index</literal> will be NULL.
1066 <literal>term</literal>: the search term itself.
1071 <literal>relation</literal>: relation for search term.
1076 <literal>modifiers</literal>: relation modifiers for search
1077 term. The <literal>modifiers</literal> is a simple linked
1078 list (NULL for last entry). Each relation modifier node
1079 is of type <literal>MOD</literal>.
1084 <literal>prefixes</literal>: index prefixes for search
1085 term. The <literal>prefixes</literal> is a simple linked
1086 list (NULL for last entry). Each prefix node
1087 is of type <literal>MOD</literal>.
1094 The boolean node represents both <literal>and</literal>,
1095 <literal>or</literal>, not as well as
1100 <literal>left</literal> and <literal>right</literal>: left
1101 - and right operand respectively.
1106 <literal>modifiers</literal>: proximity arguments.
1111 <literal>prefixes</literal>: index prefixes.
1112 The <literal>prefixes</literal> is a simple linked
1113 list (NULL for last entry). Each prefix node
1114 is of type <literal>MOD</literal>.
1121 The modifier node is a "utility" node used for name-value pairs,
1122 such as prefixes, proximity arguements, etc.
1126 <literal>name</literal> name of mod node.
1131 <literal>value</literal> value of mod node.
1136 <literal>next</literal>: pointer to next node which is
1137 always a mod node (NULL for last entry).
1144 <sect3 id="tools.cql.pqf"><title>CQL to PQF conversion</title>
1146 Conversion to PQF (and Z39.50 RPN) is tricky by the fact
1147 that the resulting RPN depends on the Z39.50 target
1148 capabilities (combinations of supported attributes).
1149 In addition, the CQL and SRW operates on index prefixes
1150 (URI or strings), whereas the RPN uses Object Identifiers
1154 The CQL library of &yaz; defines a <literal>cql_transform_t</literal>
1155 type. It represents a particular mapping between CQL and RPN.
1156 This handle is created and destroyed by the functions:
1158 cql_transform_t cql_transform_open_FILE (FILE *f);
1159 cql_transform_t cql_transform_open_fname(const char *fname);
1160 void cql_transform_close(cql_transform_t ct);
1162 The first two functions create a tranformation handle from
1163 either an already open FILE or from a filename respectively.
1166 The handle is destroyed by <function>cql_transform_close</function>
1167 in which case no further reference of the handle is allowed.
1170 When a <literal>cql_transform_t</literal> handle has been created
1171 you can convert to RPN.
1173 int cql_transform_buf(cql_transform_t ct,
1174 struct cql_node *cn, char *out, int max);
1176 This function converts the CQL tree <literal>cn</literal>
1177 using handle <literal>ct</literal>.
1178 For the resulting PQF, you supply a buffer <literal>out</literal>
1179 which must be able to hold at at least <literal>max</literal>
1183 If conversion failed, <function>cql_transform_buf</function>
1184 returns a non-zero SRW error code; otherwise zero is returned
1185 (conversion successful). The meanings of the numeric error
1186 codes are listed in the SRW specifications at
1187 <ulink url="http://www.loc.gov/srw/diagnostic-list.html"/>
1190 If conversion fails, more information can be obtained by calling
1192 int cql_transform_error(cql_transform_t ct, char **addinfop);
1194 This function returns the most recently returned numeric
1195 error-code and sets the string-pointer at
1196 <literal>*addinfop</literal> to point to a string containing
1197 additional information about the error that occurred: for
1198 example, if the error code is 15 (``Illegal or unsupported index
1199 set''), the additional information is the name of the requested
1200 index set that was not recognised.
1203 The SRW error-codes may be translated into brief human-readable
1204 error messages using
1206 const char *cql_strerror(int code);
1210 If you wish to be able to produce a PQF result in a different
1211 way, there are two alternatives.
1213 void cql_transform_pr(cql_transform_t ct,
1214 struct cql_node *cn,
1215 void (*pr)(const char *buf, void *client_data),
1218 int cql_transform_FILE(cql_transform_t ct,
1219 struct cql_node *cn, FILE *f);
1221 The former function produces output to a user-defined
1222 output stream. The latter writes the result to an already
1223 open <literal>FILE</literal>.
1226 <sect3 id="tools.cql.map">
1227 <title>Specification of CQL to RPN mapping</title>
1229 The file supplied to functions
1230 <function>cql_transform_open_FILE</function>,
1231 <function>cql_transform_open_fname</function> follows
1232 a structure found in many Unix utilities.
1233 It consists of mapping specifications - one per line.
1234 Lines starting with <literal>#</literal> are ignored (comments).
1237 Each line is of the form
1239 <replaceable>CQL pattern</replaceable><literal> = </literal> <replaceable> RPN equivalent</replaceable>
1243 An RPN pattern is a simple attribute list. Each attribute pair
1246 [<replaceable>set</replaceable>] <replaceable>type</replaceable><literal>=</literal><replaceable>value</replaceable>
1248 The attribute <replaceable>set</replaceable> is optional.
1249 The <replaceable>type</replaceable> is the attribute type,
1250 <replaceable>value</replaceable> the attribute value.
1253 The following CQL patterns are recognized:
1255 <varlistentry><term>
1256 <literal>qualifier.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1260 This pattern is invoked when a CQL qualifier, such as
1261 dc.title is converted. <replaceable>set</replaceable>
1262 and <replaceable>name</replaceable> is the index set and qualifier
1264 Typically, the RPN specifies an equivalent use attribute.
1267 For terms not bound by a qualifier the pattern
1268 <literal>qualifier.srw.serverChoice</literal> is used.
1269 Here, the prefix <literal>srw</literal> is defined as
1270 <literal>http://www.loc.gov/zing/cql/srw-indexes/v1.0/</literal>.
1271 If this pattern is not defined, the mapping will fail.
1275 <varlistentry><term>
1276 <literal>relation.</literal><replaceable>relation</replaceable>
1280 This pattern specifies how a CQL relation is mapped to RPN.
1281 <replaceable>pattern</replaceable> is name of relation
1282 operator. Since <literal>=</literal> is used as
1283 separator between CQL pattern and RPN, CQL relations
1284 including <literal>=</literal> cannot be
1285 used directly. To avoid a conflict, the names
1286 <literal>ge</literal>,
1287 <literal>eq</literal>,
1288 <literal>le</literal>,
1289 must be used for CQL operators, greater-than-or-equal,
1290 equal, less-than-or-equal respectively.
1291 The RPN pattern is supposed to include a relation attribute.
1294 For terms not bound by a relation, the pattern
1295 <literal>relation.scr</literal> is used. If the pattern
1296 is not defined, the mapping will fail.
1299 The special pattern, <literal>relation.*</literal> is used
1300 when no other relation pattern is matched.
1305 <varlistentry><term>
1306 <literal>relationModifier.</literal><replaceable>mod</replaceable>
1310 This pattern specifies how a CQL relation modifier is mapped to RPN.
1311 The RPN pattern is usually a relation attribute.
1316 <varlistentry><term>
1317 <literal>structure.</literal><replaceable>type</replaceable>
1321 This pattern specifies how a CQL structure is mapped to RPN.
1322 Note that this CQL pattern is somewhat to similar to
1323 CQL pattern <literal>relation</literal>.
1324 The <replaceable>type</replaceable> is a CQL relation.
1327 The pattern, <literal>structure.*</literal> is used
1328 when no other structure pattern is matched.
1329 Usually, the RPN equivalent specifies a structure attribute.
1334 <varlistentry><term>
1335 <literal>position.</literal><replaceable>type</replaceable>
1339 This pattern specifies how the anchor (position) of
1340 CQL is mapped to RPN.
1341 The <replaceable>type</replaceable> is one
1342 of <literal>first</literal>, <literal>any</literal>,
1343 <literal>last</literal>, <literal>firstAndLast</literal>.
1346 The pattern, <literal>position.*</literal> is used
1347 when no other position pattern is matched.
1352 <varlistentry><term>
1353 <literal>set.</literal><replaceable>prefix</replaceable>
1357 This specification defines a CQL index set for a given prefix.
1358 The value on the right hand side is the URI for the set -
1359 <emphasis>not</emphasis> RPN. All prefixes used in
1360 qualifier patterns must be defined this way.
1366 <example><title>CQL to RPN mapping file</title>
1368 This simple file defines two index sets, three qualifiers and three
1369 relations, a position pattern and a default structure.
1371 <programlisting><![CDATA[
1372 set.srw = http://www.loc.gov/zing/cql/srw-indexes/v1.0/
1373 set.dc = http://www.loc.gov/zing/cql/dc-indexes/v1.0/
1375 qualifier.srw.serverChoice = 1=1016
1376 qualifier.dc.title = 1=4
1377 qualifier.dc.subject = 1=21
1383 position.any = 3=3 6=1
1389 With the mappings above, the CQL query
1393 is converted to the PQF:
1395 @attr 1=1016 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "computer"
1397 by rules <literal>qualifier.srw.serverChoice</literal>,
1398 <literal>relation.scr</literal>, <literal>structure.*</literal>,
1399 <literal>position.any</literal>.
1406 is rejected, since <literal>position.right</literal> is
1412 >my = "http://www.loc.gov/zing/cql/dc-indexes/v1.0/" my.title = x
1416 @attr 1=4 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "x"
1421 <sect3 id="tools.cql.xcql"><title>CQL to XCQL conversion</title>
1423 Conversion from CQL to XCQL is trivial and does not
1424 require a mapping to be defined.
1425 There three functions to choose from depending on the
1426 way you wish to store the resulting output (XML buffer
1429 int cql_to_xml_buf(struct cql_node *cn, char *out, int max);
1430 void cql_to_xml(struct cql_node *cn,
1431 void (*pr)(const char *buf, void *client_data),
1433 void cql_to_xml_stdio(struct cql_node *cn, FILE *f);
1435 Function <function>cql_to_xml_buf</function> converts
1436 to XCQL and stores result in a user supplied buffer of a given
1440 <function>cql_to_xml</function> writes the result in
1441 a user defined output stream.
1442 <function>cql_to_xml_stdio</function> writes to a
1448 <sect1 id="tools.oid"><title>Object Identifiers</title>
1451 The basic YAZ representation of an OID is an array of integers,
1452 terminated with the value -1. The &odr; module provides two
1453 utility-functions to create and copy this type of data elements:
1457 Odr_oid *odr_getoidbystr(ODR o, char *str);
1461 Creates an OID based on a string-based representation using dots (.)
1462 to separate elements in the OID.
1466 Odr_oid *odr_oiddup(ODR odr, Odr_oid *o);
1470 Creates a copy of the OID referenced by the <emphasis>o</emphasis>
1472 Both functions take an &odr; stream as parameter. This stream is used to
1473 allocate memory for the data elements, which is released on a
1474 subsequent call to <function>odr_reset()</function> on that stream.
1478 The OID module provides a higher-level representation of the
1479 family of object identifiers which describe the Z39.50 protocol and its
1480 related objects. The definition of the module interface is given in
1481 the <filename>oid.h</filename> file.
1485 The interface is mainly based on the <literal>oident</literal> structure.
1486 The definition of this structure looks like this:
1490 typedef struct oident
1495 int oidsuffix[OID_SIZE];
1501 The proto field takes one of the values
1510 Use <literal>PROTO_Z3950</literal> for Z39.50 Object Identifers,
1511 <literal>PROTO_GENERAL</literal> for other types (such as
1512 those associated with ILL).
1516 The oclass field takes one of the values
1538 corresponding to the OID classes defined by the Z39.50 standard.
1540 Finally, the value field takes one of the values
1598 again, corresponding to the specific OIDs defined by the standard.
1600 <ulink url="http://lcweb.loc.gov/z3950/agency/defns/oids.html">
1601 Registry of Z39.50 Object Identifiers</ulink> for the
1606 The desc field contains a brief, mnemonic name for the OID in question.
1614 struct oident *oid_getentbyoid(int *o);
1618 takes as argument an OID, and returns a pointer to a static area
1619 containing an <literal>oident</literal> structure. You typically use
1620 this function when you receive a PDU containing an OID, and you wish
1621 to branch out depending on the specific OID value.
1629 int *oid_ent_to_oid(struct oident *ent, int *dst);
1633 Takes as argument an <literal>oident</literal> structure - in which
1634 the <literal>proto</literal>, <literal>oclass</literal>/, and
1635 <literal>value</literal> fields are assumed to be set correctly -
1636 and returns a pointer to a the buffer as given by <literal>dst</literal>
1638 representation of the corresponding OID. The function returns
1639 NULL and the array dst is unchanged if a mapping couldn't place.
1640 The array <literal>dst</literal> should be at least of size
1641 <literal>OID_SIZE</literal>.
1645 The <function>oid_ent_to_oid()</function> function can be used whenever
1646 you need to prepare a PDU containing one or more OIDs. The separation of
1647 the <literal>protocol</literal> element from the remainder of the
1648 OID-description makes it simple to write applications that can
1649 communicate with either Z39.50 or OSI SR-based applications.
1657 oid_value oid_getvalbyname(const char *name);
1661 takes as argument a mnemonic OID name, and returns the
1662 <literal>/value</literal> field of the first entry in the database that
1663 contains the given name in its <literal>desc</literal> field.
1667 Three utility functions are provided for translating OIDs'
1668 symbolic names (e.g. <literal>Usmarc</literal> into OID structures
1669 (int arrays) and strings containing the OID in dotted notation
1670 (e.g. <literal>1.2.840.10003.9.5.1</literal>). They are:
1674 int *oid_name_to_oid(oid_class oclass, const char *name, int *oid);
1675 char *oid_to_dotstring(const int *oid, char *oidbuf);
1676 char *oid_name_to_dotstring(oid_class oclass, const char *name, char *oidbuf);
1680 <literal>oid_name_to_oid()</literal>
1681 translates the specified symbolic <literal>name</literal>,
1682 interpreted as being of class <literal>oclass</literal>. (The
1683 class must be specified as many symbolic names exist within
1684 multiple classes - for example, <literal>Zthes</literal> is the
1685 symbolic name of an attribute set, a schema and a tag-set.) The
1686 sequence of integers representing the OID is written into the
1687 area <literal>oid</literal> provided by the caller; it is the
1688 caller's responsibility to ensure that this area is large enough
1689 to contain the translated OID. As a convenience, the address of
1690 the buffer (i.e. the value of <literal>oid</literal>) is
1694 <literal>oid_to_dotstring()</literal>
1695 Translates the int-array <literal>oid</literal> into a dotted
1696 string which is written into the area <literal>oidbuf</literal>
1697 supplied by the caller; it is the caller's responsibility to
1698 ensure that this area is large enough. The address of the buffer
1702 <literal>oid_name_to_dotstring()</literal>
1703 combines the previous two functions to derive a dotted string
1704 representing the OID specified by <literal>oclass</literal> and
1705 <literal>name</literal>, writing it into the buffer passed as
1706 <literal>oidbuf</literal> and returning its address.
1710 Finally, the module provides the following utility functions, whose
1711 meaning should be obvious:
1715 void oid_oidcpy(int *t, int *s);
1716 void oid_oidcat(int *t, int *s);
1717 int oid_oidcmp(int *o1, int *o2);
1718 int oid_oidlen(int *o);
1723 The OID module has been criticized - and perhaps rightly so
1724 - for needlessly abstracting the
1725 representation of OIDs. Other toolkits use a simple
1726 string-representation of OIDs with good results. In practice, we have
1727 found the interface comfortable and quick to work with, and it is a
1728 simple matter (for what it's worth) to create applications compatible
1729 with both ISO SR and Z39.50. Finally, the use of the
1730 <literal>/oident</literal> database is by no means mandatory.
1731 You can easily create your own system for representing OIDs, as long
1732 as it is compatible with the low-level integer-array representation
1739 <sect1 id="tools.nmem"><title>Nibble Memory</title>
1742 Sometimes when you need to allocate and construct a large,
1743 interconnected complex of structures, it can be a bit of a pain to
1744 release the associated memory again. For the structures describing the
1745 Z39.50 PDUs and related structures, it is convenient to use the
1746 memory-management system of the &odr; subsystem (see
1747 <link linkend="odr-use">Using ODR</link>). However, in some circumstances
1748 where you might otherwise benefit from using a simple nibble memory
1749 management system, it may be impractical to use
1750 <function>odr_malloc()</function> and <function>odr_reset()</function>.
1751 For this purpose, the memory manager which also supports the &odr;
1752 streams is made available in the NMEM module. The external interface
1753 to this module is given in the <filename>nmem.h</filename> file.
1757 The following prototypes are given:
1761 NMEM nmem_create(void);
1762 void nmem_destroy(NMEM n);
1763 void *nmem_malloc(NMEM n, int size);
1764 void nmem_reset(NMEM n);
1765 int nmem_total(NMEM n);
1766 void nmem_init(void);
1767 void nmem_exit(void);
1771 The <function>nmem_create()</function> function returns a pointer to a
1772 memory control handle, which can be released again by
1773 <function>nmem_destroy()</function> when no longer needed.
1774 The function <function>nmem_malloc()</function> allocates a block of
1775 memory of the requested size. A call to <function>nmem_reset()</function>
1776 or <function>nmem_destroy()</function> will release all memory allocated
1777 on the handle since it was created (or since the last call to
1778 <function>nmem_reset()</function>. The function
1779 <function>nmem_total()</function> returns the number of bytes currently
1780 allocated on the handle.
1784 The nibble memory pool is shared amongst threads. POSIX
1785 mutex'es and WIN32 Critical sections are introduced to keep the
1786 module thread safe. Function <function>nmem_init()</function>
1787 initializes the nibble memory library and it is called automatically
1788 the first time the <literal>YAZ.DLL</literal> is loaded. &yaz; uses
1789 function <function>DllMain</function> to achieve this. You should
1790 <emphasis>not</emphasis> call <function>nmem_init</function> or
1791 <function>nmem_exit</function> unless you're absolute sure what
1792 you're doing. Note that in previous &yaz; versions you'd have to call
1793 <function>nmem_init</function> yourself.
1799 <!-- Keep this comment at the end of the file
1804 sgml-minimize-attributes:nil
1805 sgml-always-quote-attributes:t
1808 sgml-parent-document: "yaz.xml"
1809 sgml-local-catalogs: nil
1810 sgml-namecase-general:t