1 <!-- $Id: tools.xml,v 1.31 2003-11-03 10:47:24 adam 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48 is obsolete and is only provided to ensure backwards compatibility.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 <example><title>PQF queries using simple terms</title>
312 <example><title>PQF boolean operators</title>
315 @or "dylan" "zimmerman"
316 @and @or dylan zimmerman when
317 @and when @or dylan zimmerman
321 <example><title>PQF references to result sets</title>
329 <example><title>Attributes for terms</title>
333 @attr 1=4 @attr 4=1 "self portrait"
334 @attrset exp1 @attr 1=1 CategoryList
335 @attr gils 1=2008 Copenhagen
336 @attr 1=/book/title computer
340 <example><title>PQF Proximity queries</title>
343 @prox 0 3 1 2 k 2 dylan zimmerman
346 Here the parameters 0, 3, 1, 2, k and 2 represent exclusion,
347 distance, ordered, relation, which-code and unit-code, in that
351 exclusion = 0: the proximity condition must hold
354 distance = 3: the terms must be three units apart
357 ordered = 1: they must occur in the order they are specified
360 relation = 2: lessThanOrEqual (to the distance of 3 units)
363 which-code is ``known'', so the standard unit-codes are used
369 So the whole proximity query means that the words
370 <literal>dylan</literal> and <literal>zimmerman</literal> must
371 both occur in the record, in that order, differing in position
372 by three or fewer words (i.e. with two or fewer words between
373 them.) The query would find ``Bob Dylan, aka. Robert
374 Zimmerman'', but not ``Bob Dylan, born as Robert Zimmerman''
375 since the distance in this case is four.
379 <example><title>PQF specification of search term</title>
382 @term string "a UTF-8 string, maybe?"
386 <example><title>PQF mixed queries</title>
389 @or @and bob dylan @set Result-1
391 @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming"
393 @and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109
397 The last of these examples is a spatial search: in
398 <ulink url="http://www.gils.net/prof_v2.html#sec_7_4"
399 >the GILS attribute set</ulink>,
401 2038 indicates West Bounding Coordinate and
402 2030 indicates East Bounding Coordinate,
403 so the query is for areas extending from -114 degrees
404 to no more than -109 degrees.
411 <sect2 id="CCL"><title>CCL</title>
414 Not all users enjoy typing in prefix query structures and numerical
415 attribute values, even in a minimalistic test client. In the library
416 world, the more intuitive Common Command Language - CCL (ISO 8777)
417 has enjoyed some popularity - especially before the widespread
418 availability of graphical interfaces. It is still useful in
419 applications where you for some reason or other need to provide a
420 symbolic language for expressing boolean query structures.
424 The <ulink url="http://europagate.dtv.dk/">EUROPAGATE</ulink>
425 research project working under the Libraries programme
426 of the European Commission's DG XIII has, amongst other useful tools,
427 implemented a general-purpose CCL parser which produces an output
428 structure that can be trivially converted to the internal RPN
429 representation of &yaz; (The <literal>Z_RPNQuery</literal> structure).
430 Since the CCL utility - along with the rest of the software
431 produced by EUROPAGATE - is made freely available on a liberal
432 license, it is included as a supplement to &yaz;.
435 <sect3><title>CCL Syntax</title>
438 The CCL parser obeys the following grammar for the FIND argument.
439 The syntax is annotated by in the lines prefixed by
440 <literal>‐‐</literal>.
444 CCL-Find ::= CCL-Find Op Elements
447 Op ::= "and" | "or" | "not"
448 -- The above means that Elements are separated by boolean operators.
450 Elements ::= '(' CCL-Find ')'
453 | Qualifiers Relation Terms
454 | Qualifiers Relation '(' CCL-Find ')'
455 | Qualifiers '=' string '-' string
456 -- Elements is either a recursive definition, a result set reference, a
457 -- list of terms, qualifiers followed by terms, qualifiers followed
458 -- by a recursive definition or qualifiers in a range (lower - upper).
460 Set ::= 'set' = string
461 -- Reference to a result set
463 Terms ::= Terms Prox Term
465 -- Proximity of terms.
469 -- This basically means that a term may include a blank
471 Qualifiers ::= Qualifiers ',' string
473 -- Qualifiers is a list of strings separated by comma
475 Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<'
476 -- Relational operators. This really doesn't follow the ISO8777
480 -- Proximity operator
484 <example><title>CCL queries</title>
486 The following queries are all valid:
498 (dylan and bob) or set=1
502 Assuming that the qualifiers <literal>ti</literal>,
503 <literal>au</literal>
504 and <literal>date</literal> are defined we may use:
510 au=(bob dylan and slow train coming)
512 date>1980 and (ti=((self portrait)))
518 <sect3><title>CCL Qualifiers</title>
521 Qualifiers are used to direct the search to a particular searchable
522 index, such as title (ti) and author indexes (au). The CCL standard
523 itself doesn't specify a particular set of qualifiers, but it does
524 suggest a few short-hand notations. You can customize the CCL parser
525 to support a particular set of qualifiers to reflect the current target
526 profile. Traditionally, a qualifier would map to a particular
527 use-attribute within the BIB-1 attribute set. It is also
528 possible to set other attributes, such as the structure
533 A CCL profile is a set of predefined CCL qualifiers that may be
534 read from a file or set in the CCL API.
535 The YAZ client reads its CCL qualifiers from a file named
536 <filename>default.bib</filename>. There are four types of
537 lines in a CCL profile: qualifier specification,
538 qualifier alias, comments and directives.
540 <sect4><title id="qualifier-specification">Qualifier specification</title>
542 A qualifier specification is of the form:
546 <replaceable>qualifier-name</replaceable>
547 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable>
548 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable> ...
552 where <replaceable>qualifier-name</replaceable> is the name of the
553 qualifier to be used (eg. <literal>ti</literal>),
554 <replaceable>type</replaceable> is attribute type in the attribute
555 set (Bib-1 is used if no attribute set is given) and
556 <replaceable>val</replaceable> is attribute value.
557 The <replaceable>type</replaceable> can be specified as an
558 integer or as it be specified either as a single-letter:
559 <literal>u</literal> for use,
560 <literal>r</literal> for relation,<literal>p</literal> for position,
561 <literal>s</literal> for structure,<literal>t</literal> for truncation
562 or <literal>c</literal> for completeness.
563 The attributes for the special qualifier name <literal>term</literal>
564 are used when no CCL qualifier is given in a query.
565 <table><title>Common Bib-1 attributes</title>
567 <colspec colwidth="2*" colname="type"></colspec>
568 <colspec colwidth="9*" colname="description"></colspec>
572 <entry>Description</entry>
577 <entry><literal>u=</literal><replaceable>value</replaceable></entry>
579 Use attribute. Common use attributes are
580 1 Personal-name, 4 Title, 7 ISBN, 8 ISSN, 30 Date,
581 62 Subject, 1003 Author), 1016 Any. Specify value
587 <entry><literal>r=</literal><replaceable>value</replaceable></entry>
589 Relation attribute. Common values are
590 1 <, 2 <=, 3 =, 4 >=, 5 >, 6 <>,
591 100 phonetic, 101 stem, 102 relevance, 103 always matches.
596 <entry><literal>p=</literal><replaceable>value</replaceable></entry>
598 Position attribute. Values: 1 first in field, 2
599 first in any subfield, 3 any position in field.
604 <entry><literal>s=</literal><replaceable>value</replaceable></entry>
606 Structure attribute. Values: 1 phrase, 2 word,
607 3 key, 4 year, 5 date, 6 word list, 100 date (un),
608 101 name (norm), 102 name (un), 103 structure, 104 urx,
609 105 free-form-text, 106 document-text, 107 local-number,
610 108 string, 109 numeric string.
615 <entry><literal>t=</literal><replaceable>value</replaceable></entry>
617 Truncation attribute. Values: 1 right, 2 left,
618 3 left& right, 100 none, 101 process #, 102 regular-1,
619 103 regular-2, 104 CCL.
624 <entry><literal>c=</literal><replaceable>value</replaceable></entry>
626 Completeness attribute. Values: 1 incomplete subfield,
627 2 complete subfield, 3 complete field.
636 The complete list of Bib-1 attributes can be found
637 <ulink url="http://lcweb.loc.gov/z3950/agency/defns/bib1.html">
642 It is also possible to specify non-numeric attribute values,
643 which are used in combination with certain types.
644 The special combinations are:
646 <table><title>Special attribute combos</title>
648 <colspec colwidth="2*" colname="name"></colspec>
649 <colspec colwidth="9*" colname="description"></colspec>
653 <entry>Description</entry>
658 <entry><literal>s=pw</literal></entry><entry>
659 The structure is set to either word or phrase depending
660 on the number of tokens in a term (phrase-word).
664 <entry><literal>s=al</literal></entry><entry>
665 Each token in the term is ANDed. (and-list).
666 This does not set the structure at all.
670 <row><entry><literal>s=ol</literal></entry><entry>
671 Each token in the term is ORed. (or-list).
672 This does not set the structure at all.
676 <row><entry><literal>r=o</literal></entry><entry>
677 Allows operators greather-than, less-than, ... equals and
678 sets relation attribute accordingly (relation ordered).
682 <row><entry><literal>t=l</literal></entry><entry>
683 Allows term to be left-truncated.
684 If term is of the form <literal>?x</literal>, the resulting
685 Type-1 term is <literal>x</literal> and truncation is left.
689 <row><entry><literal>t=r</literal></entry><entry>
690 Allows term to be right-truncated.
691 If term is of the form <literal>x?</literal>, the resulting
692 Type-1 term is <literal>x</literal> and truncation is right.
696 <row><entry><literal>t=n</literal></entry><entry>
697 If term is does not include <literal>?</literal>, the
698 truncation attribute is set to none (100).
702 <row><entry><literal>t=b</literal></entry><entry>
703 Allows term to be both left&right truncated.
704 If term is of the form <literal>?x?</literal>, the
705 resulting term is <literal>x</literal> and trunctation is
706 set to both left&right.
713 <example><title>CCL profile</title>
715 Consider the following definition:
726 Four qualifiers are defined - <literal>ti</literal>,
727 <literal>au</literal>, <literal>ranked</literal> and
728 <literal>date</literal>.
731 <literal>ti</literal> and <literal>au</literal> both set
732 structure attribute to phrase (s=1).
733 <literal>ti</literal>
734 sets the use-attribute to 4. <literal>au</literal> sets the
736 When no qualifiers are used in the query the structure-attribute is
737 set to free-form-text (105) (rule for <literal>term</literal>).
738 The <literal>date</literal> sets the relation attribute to
739 the relation used in the CCL query and sets the use attribute
743 You can combine attributes. To Search for "ranked title" you
746 ti,ranked=knuth computer
748 which will set relation=ranked, use=title, structure=phrase.
755 is a valid query, while
763 <sect4><title>Qualifier alias</title>
765 A qualifier alias is of the form:
768 <replaceable>q</replaceable>
769 <replaceable>q1</replaceable> <replaceable>q2</replaceable> ..
772 which declares <replaceable>q</replaceable> to
773 be an alias for <replaceable>q1</replaceable>,
774 <replaceable>q2</replaceable>... such that the CCL
775 query <replaceable>q=x</replaceable> is equivalent to
776 <replaceable>q1=x or w2=x or ...</replaceable>.
780 <sect4><title>Comments</title>
782 Lines with white space or lines that begin with
783 character <literal>#</literal> are treated as comments.
787 <sect4><title>Directives</title>
789 Directive specifications takes the form
791 <para><literal>@</literal><replaceable>directive</replaceable> <replaceable>value</replaceable>
793 <table><title>CCL directives</title>
795 <colspec colwidth="2*" colname="name"></colspec>
796 <colspec colwidth="8*" colname="description"></colspec>
797 <colspec colwidth="1*" colname="default"></colspec>
801 <entry>Description</entry>
802 <entry>Default</entry>
807 <entry>truncation</entry>
808 <entry>Truncation character</entry>
809 <entry><literal>?</literal></entry>
813 <entry>Specifies how multiple fields are to be
814 combined. There are two modes: <literal>or</literal>:
815 multiple qualifier fields are ORed,
816 <literal>merge</literal>: attributes for the qualifier
817 fields are merged and assigned to one term.
819 <entry><literal>merge</literal></entry>
823 <entry>Specificies if CCL operatores and qualifiers should be
824 compared with case sensitivity or not. Specify 0 for
825 case sensitive; 1 for case insensitive.</entry>
826 <entry><literal>0</literal></entry>
831 <entry>Specifies token for CCL operator AND.</entry>
832 <entry><literal>and</literal></entry>
837 <entry>Specifies token for CCL operator OR.</entry>
838 <entry><literal>or</literal></entry>
843 <entry>Specifies token for CCL operator NOT.</entry>
844 <entry><literal>not</literal></entry>
849 <entry>Specifies token for CCL operator SET.</entry>
850 <entry><literal>set</literal></entry>
857 <sect3><title>CCL API</title>
859 All public definitions can be found in the header file
860 <filename>ccl.h</filename>. A profile identifier is of type
861 <literal>CCL_bibset</literal>. A profile must be created with the call
862 to the function <function>ccl_qual_mk</function> which returns a profile
863 handle of type <literal>CCL_bibset</literal>.
867 To read a file containing qualifier definitions the function
868 <function>ccl_qual_file</function> may be convenient. This function
869 takes an already opened <literal>FILE</literal> handle pointer as
870 argument along with a <literal>CCL_bibset</literal> handle.
874 To parse a simple string with a FIND query use the function
877 struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str,
878 int *error, int *pos);
881 which takes the CCL profile (<literal>bibset</literal>) and query
882 (<literal>str</literal>) as input. Upon successful completion the RPN
883 tree is returned. If an error occur, such as a syntax error, the integer
884 pointed to by <literal>error</literal> holds the error code and
885 <literal>pos</literal> holds the offset inside query string in which
890 An English representation of the error may be obtained by calling
891 the <literal>ccl_err_msg</literal> function. The error codes are
892 listed in <filename>ccl.h</filename>.
896 To convert the CCL RPN tree (type
897 <literal>struct ccl_rpn_node *</literal>)
898 to the Z_RPNQuery of YAZ the function <function>ccl_rpn_query</function>
899 must be used. This function which is part of YAZ is implemented in
900 <filename>yaz-ccl.c</filename>.
901 After calling this function the CCL RPN tree is probably no longer
902 needed. The <literal>ccl_rpn_delete</literal> destroys the CCL RPN tree.
906 A CCL profile may be destroyed by calling the
907 <function>ccl_qual_rm</function> function.
911 The token names for the CCL operators may be changed by setting the
912 globals (all type <literal>char *</literal>)
913 <literal>ccl_token_and</literal>, <literal>ccl_token_or</literal>,
914 <literal>ccl_token_not</literal> and <literal>ccl_token_set</literal>.
915 An operator may have aliases, i.e. there may be more than one name for
916 the operator. To do this, separate each alias with a space character.
920 <sect2 id="tools.cql"><title>CQL</title>
922 <ulink url="http://www.loc.gov/z3950/agency/zing/cql/">CQL</ulink>
923 - Common Query Language - was defined for the
924 <ulink url="http://www.loc.gov/z3950/agency/zing/srw/">SRW</ulink>
926 In many ways CQL has a similar syntax to CCL.
927 The objective of CQL is different. Where CCL aims to be
928 an end-user language, CQL is <emphasis>the</emphasis> protocol
929 query language for SRW.
933 If you are new to CQL, read the
934 <ulink url="http://zing.z3950.org/cql/intro.html">Gentle
935 Introduction</ulink>.
939 The CQL parser in &yaz; provides the following:
943 It parses and validates a CQL query.
948 It generates a C structure that allows you to convert
949 a CQL query to some other query language, such as SQL.
954 The parser converts a valid CQL query to PQF, thus providing a
955 way to use CQL for both SRW/SRU servers and Z39.50 targets at the
961 The parser converts CQL to
962 <ulink url="http://www.loc.gov/z3950/agency/zing/cql/xcql.html">
964 XCQL is an XML representation of CQL.
965 XCQL is part of the SRW specification. However, since SRU
966 supports CQL only, we don't expect XCQL to be widely used.
967 Furthermore, CQL has the advantage over XCQL that it is
973 <sect3 id="tools.cql.parsing"><title>CQL parsing</title>
975 A CQL parser is represented by the <literal>CQL_parser</literal>
976 handle. Its contents should be considered &yaz; internal (private).
978 #include <yaz/cql.h>
980 typedef struct cql_parser *CQL_parser;
982 CQL_parser cql_parser_create(void);
983 void cql_parser_destroy(CQL_parser cp);
985 A parser is created by <function>cql_parser_create</function> and
986 is destroyed by <function>cql_parser_destroy</function>.
989 To parse a CQL query string, the following function
992 int cql_parser_string(CQL_parser cp, const char *str);
994 A CQL query is parsed by the <function>cql_parser_string</function>
995 which takes a query <parameter>str</parameter>.
996 If the query was valid (no syntax errors), then zero is returned;
997 otherwise -1 is returned to indicate a syntax error.
1001 int cql_parser_stream(CQL_parser cp,
1002 int (*getbyte)(void *client_data),
1003 void (*ungetbyte)(int b, void *client_data),
1006 int cql_parser_stdio(CQL_parser cp, FILE *f);
1008 The functions <function>cql_parser_stream</function> and
1009 <function>cql_parser_stdio</function> parses a CQL query
1010 - just like <function>cql_parser_string</function>.
1011 The only difference is that the CQL query can be
1012 fed to the parser in different ways.
1013 The <function>cql_parser_stream</function> uses a generic
1014 byte stream as input. The <function>cql_parser_stdio</function>
1015 uses a <literal>FILE</literal> handle which is opened for reading.
1019 <sect3 id="tools.cql.tree"><title>CQL tree</title>
1021 The the query string is valid, the CQL parser
1022 generates a tree representing the structure of the
1027 struct cql_node *cql_parser_result(CQL_parser cp);
1029 <function>cql_parser_result</function> returns the
1030 a pointer to the root node of the resulting tree.
1033 Each node in a CQL tree is represented by a
1034 <literal>struct cql_node</literal>.
1035 It is defined as follows:
1037 #define CQL_NODE_ST 1
1038 #define CQL_NODE_BOOL 2
1039 #define CQL_NODE_MOD 3
1047 struct cql_node *modifiers;
1048 struct cql_node *prefixes;
1052 struct cql_node *left;
1053 struct cql_node *right;
1054 struct cql_node *modifiers;
1055 struct cql_node *prefixes;
1060 struct cql_node *next;
1065 There are three kinds of nodes, search term (ST), boolean (BOOL),
1069 The search term node has five members:
1073 <literal>index</literal>: index for search term.
1074 If an index is unspecified for a search term,
1075 <literal>index</literal> will be NULL.
1080 <literal>term</literal>: the search term itself.
1085 <literal>relation</literal>: relation for search term.
1090 <literal>modifiers</literal>: relation modifiers for search
1091 term. The <literal>modifiers</literal> is a simple linked
1092 list (NULL for last entry). Each relation modifier node
1093 is of type <literal>MOD</literal>.
1098 <literal>prefixes</literal>: index prefixes for search
1099 term. The <literal>prefixes</literal> is a simple linked
1100 list (NULL for last entry). Each prefix node
1101 is of type <literal>MOD</literal>.
1108 The boolean node represents both <literal>and</literal>,
1109 <literal>or</literal>, not as well as
1114 <literal>left</literal> and <literal>right</literal>: left
1115 - and right operand respectively.
1120 <literal>modifiers</literal>: proximity arguments.
1125 <literal>prefixes</literal>: index prefixes.
1126 The <literal>prefixes</literal> is a simple linked
1127 list (NULL for last entry). Each prefix node
1128 is of type <literal>MOD</literal>.
1135 The modifier node is a "utility" node used for name-value pairs,
1136 such as prefixes, proximity arguements, etc.
1140 <literal>name</literal> name of mod node.
1145 <literal>value</literal> value of mod node.
1150 <literal>next</literal>: pointer to next node which is
1151 always a mod node (NULL for last entry).
1158 <sect3 id="tools.cql.pqf"><title>CQL to PQF conversion</title>
1160 Conversion to PQF (and Z39.50 RPN) is tricky by the fact
1161 that the resulting RPN depends on the Z39.50 target
1162 capabilities (combinations of supported attributes).
1163 In addition, the CQL and SRW operates on index prefixes
1164 (URI or strings), whereas the RPN uses Object Identifiers
1168 The CQL library of &yaz; defines a <literal>cql_transform_t</literal>
1169 type. It represents a particular mapping between CQL and RPN.
1170 This handle is created and destroyed by the functions:
1172 cql_transform_t cql_transform_open_FILE (FILE *f);
1173 cql_transform_t cql_transform_open_fname(const char *fname);
1174 void cql_transform_close(cql_transform_t ct);
1176 The first two functions create a tranformation handle from
1177 either an already open FILE or from a filename respectively.
1180 The handle is destroyed by <function>cql_transform_close</function>
1181 in which case no further reference of the handle is allowed.
1184 When a <literal>cql_transform_t</literal> handle has been created
1185 you can convert to RPN.
1187 int cql_transform_buf(cql_transform_t ct,
1188 struct cql_node *cn, char *out, int max);
1190 This function converts the CQL tree <literal>cn</literal>
1191 using handle <literal>ct</literal>.
1192 For the resulting PQF, you supply a buffer <literal>out</literal>
1193 which must be able to hold at at least <literal>max</literal>
1197 If conversion failed, <function>cql_transform_buf</function>
1198 returns a non-zero SRW error code; otherwise zero is returned
1199 (conversion successful). The meanings of the numeric error
1200 codes are listed in the SRW specifications at
1201 <ulink url="http://www.loc.gov/srw/diagnostic-list.html"/>
1204 If conversion fails, more information can be obtained by calling
1206 int cql_transform_error(cql_transform_t ct, char **addinfop);
1208 This function returns the most recently returned numeric
1209 error-code and sets the string-pointer at
1210 <literal>*addinfop</literal> to point to a string containing
1211 additional information about the error that occurred: for
1212 example, if the error code is 15 (``Illegal or unsupported index
1213 set''), the additional information is the name of the requested
1214 index set that was not recognised.
1217 The SRW error-codes may be translated into brief human-readable
1218 error messages using
1220 const char *cql_strerror(int code);
1224 If you wish to be able to produce a PQF result in a different
1225 way, there are two alternatives.
1227 void cql_transform_pr(cql_transform_t ct,
1228 struct cql_node *cn,
1229 void (*pr)(const char *buf, void *client_data),
1232 int cql_transform_FILE(cql_transform_t ct,
1233 struct cql_node *cn, FILE *f);
1235 The former function produces output to a user-defined
1236 output stream. The latter writes the result to an already
1237 open <literal>FILE</literal>.
1240 <sect3 id="tools.cql.map">
1241 <title>Specification of CQL to RPN mapping</title>
1243 The file supplied to functions
1244 <function>cql_transform_open_FILE</function>,
1245 <function>cql_transform_open_fname</function> follows
1246 a structure found in many Unix utilities.
1247 It consists of mapping specifications - one per line.
1248 Lines starting with <literal>#</literal> are ignored (comments).
1251 Each line is of the form
1253 <replaceable>CQL pattern</replaceable><literal> = </literal> <replaceable> RPN equivalent</replaceable>
1257 An RPN pattern is a simple attribute list. Each attribute pair
1260 [<replaceable>set</replaceable>] <replaceable>type</replaceable><literal>=</literal><replaceable>value</replaceable>
1262 The attribute <replaceable>set</replaceable> is optional.
1263 The <replaceable>type</replaceable> is the attribute type,
1264 <replaceable>value</replaceable> the attribute value.
1267 The following CQL patterns are recognized:
1269 <varlistentry><term>
1270 <literal>qualifier.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1274 This pattern is invoked when a CQL qualifier, such as
1275 dc.title is converted. <replaceable>set</replaceable>
1276 and <replaceable>name</replaceable> is the index set and qualifier
1278 Typically, the RPN specifies an equivalent use attribute.
1281 For terms not bound by a qualifier the pattern
1282 <literal>qualifier.srw.serverChoice</literal> is used.
1283 Here, the prefix <literal>srw</literal> is defined as
1284 <literal>http://www.loc.gov/zing/cql/srw-indexes/v1.0/</literal>.
1285 If this pattern is not defined, the mapping will fail.
1289 <varlistentry><term>
1290 <literal>relation.</literal><replaceable>relation</replaceable>
1294 This pattern specifies how a CQL relation is mapped to RPN.
1295 <replaceable>pattern</replaceable> is name of relation
1296 operator. Since <literal>=</literal> is used as
1297 separator between CQL pattern and RPN, CQL relations
1298 including <literal>=</literal> cannot be
1299 used directly. To avoid a conflict, the names
1300 <literal>ge</literal>,
1301 <literal>eq</literal>,
1302 <literal>le</literal>,
1303 must be used for CQL operators, greater-than-or-equal,
1304 equal, less-than-or-equal respectively.
1305 The RPN pattern is supposed to include a relation attribute.
1308 For terms not bound by a relation, the pattern
1309 <literal>relation.scr</literal> is used. If the pattern
1310 is not defined, the mapping will fail.
1313 The special pattern, <literal>relation.*</literal> is used
1314 when no other relation pattern is matched.
1319 <varlistentry><term>
1320 <literal>relationModifier.</literal><replaceable>mod</replaceable>
1324 This pattern specifies how a CQL relation modifier is mapped to RPN.
1325 The RPN pattern is usually a relation attribute.
1330 <varlistentry><term>
1331 <literal>structure.</literal><replaceable>type</replaceable>
1335 This pattern specifies how a CQL structure is mapped to RPN.
1336 Note that this CQL pattern is somewhat to similar to
1337 CQL pattern <literal>relation</literal>.
1338 The <replaceable>type</replaceable> is a CQL relation.
1341 The pattern, <literal>structure.*</literal> is used
1342 when no other structure pattern is matched.
1343 Usually, the RPN equivalent specifies a structure attribute.
1348 <varlistentry><term>
1349 <literal>position.</literal><replaceable>type</replaceable>
1353 This pattern specifies how the anchor (position) of
1354 CQL is mapped to RPN.
1355 The <replaceable>type</replaceable> is one
1356 of <literal>first</literal>, <literal>any</literal>,
1357 <literal>last</literal>, <literal>firstAndLast</literal>.
1360 The pattern, <literal>position.*</literal> is used
1361 when no other position pattern is matched.
1366 <varlistentry><term>
1367 <literal>set.</literal><replaceable>prefix</replaceable>
1371 This specification defines a CQL index set for a given prefix.
1372 The value on the right hand side is the URI for the set -
1373 <emphasis>not</emphasis> RPN. All prefixes used in
1374 qualifier patterns must be defined this way.
1380 <example><title>CQL to RPN mapping file</title>
1382 This simple file defines two index sets, three qualifiers and three
1383 relations, a position pattern and a default structure.
1385 <programlisting><![CDATA[
1386 set.srw = http://www.loc.gov/zing/cql/srw-indexes/v1.0/
1387 set.dc = http://www.loc.gov/zing/cql/dc-indexes/v1.0/
1389 qualifier.srw.serverChoice = 1=1016
1390 qualifier.dc.title = 1=4
1391 qualifier.dc.subject = 1=21
1397 position.any = 3=3 6=1
1403 With the mappings above, the CQL query
1407 is converted to the PQF:
1409 @attr 1=1016 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "computer"
1411 by rules <literal>qualifier.srw.serverChoice</literal>,
1412 <literal>relation.scr</literal>, <literal>structure.*</literal>,
1413 <literal>position.any</literal>.
1420 is rejected, since <literal>position.right</literal> is
1426 >my = "http://www.loc.gov/zing/cql/dc-indexes/v1.0/" my.title = x
1430 @attr 1=4 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "x"
1435 <sect3 id="tools.cql.xcql"><title>CQL to XCQL conversion</title>
1437 Conversion from CQL to XCQL is trivial and does not
1438 require a mapping to be defined.
1439 There three functions to choose from depending on the
1440 way you wish to store the resulting output (XML buffer
1443 int cql_to_xml_buf(struct cql_node *cn, char *out, int max);
1444 void cql_to_xml(struct cql_node *cn,
1445 void (*pr)(const char *buf, void *client_data),
1447 void cql_to_xml_stdio(struct cql_node *cn, FILE *f);
1449 Function <function>cql_to_xml_buf</function> converts
1450 to XCQL and stores result in a user supplied buffer of a given
1454 <function>cql_to_xml</function> writes the result in
1455 a user defined output stream.
1456 <function>cql_to_xml_stdio</function> writes to a
1462 <sect1 id="tools.oid"><title>Object Identifiers</title>
1465 The basic YAZ representation of an OID is an array of integers,
1466 terminated with the value -1. The &odr; module provides two
1467 utility-functions to create and copy this type of data elements:
1471 Odr_oid *odr_getoidbystr(ODR o, char *str);
1475 Creates an OID based on a string-based representation using dots (.)
1476 to separate elements in the OID.
1480 Odr_oid *odr_oiddup(ODR odr, Odr_oid *o);
1484 Creates a copy of the OID referenced by the <emphasis>o</emphasis>
1486 Both functions take an &odr; stream as parameter. This stream is used to
1487 allocate memory for the data elements, which is released on a
1488 subsequent call to <function>odr_reset()</function> on that stream.
1492 The OID module provides a higher-level representation of the
1493 family of object identifiers which describe the Z39.50 protocol and its
1494 related objects. The definition of the module interface is given in
1495 the <filename>oid.h</filename> file.
1499 The interface is mainly based on the <literal>oident</literal> structure.
1500 The definition of this structure looks like this:
1504 typedef struct oident
1509 int oidsuffix[OID_SIZE];
1515 The proto field takes one of the values
1524 Use <literal>PROTO_Z3950</literal> for Z39.50 Object Identifers,
1525 <literal>PROTO_GENERAL</literal> for other types (such as
1526 those associated with ILL).
1530 The oclass field takes one of the values
1552 corresponding to the OID classes defined by the Z39.50 standard.
1554 Finally, the value field takes one of the values
1612 again, corresponding to the specific OIDs defined by the standard.
1614 <ulink url="http://lcweb.loc.gov/z3950/agency/defns/oids.html">
1615 Registry of Z39.50 Object Identifiers</ulink> for the
1620 The desc field contains a brief, mnemonic name for the OID in question.
1628 struct oident *oid_getentbyoid(int *o);
1632 takes as argument an OID, and returns a pointer to a static area
1633 containing an <literal>oident</literal> structure. You typically use
1634 this function when you receive a PDU containing an OID, and you wish
1635 to branch out depending on the specific OID value.
1643 int *oid_ent_to_oid(struct oident *ent, int *dst);
1647 Takes as argument an <literal>oident</literal> structure - in which
1648 the <literal>proto</literal>, <literal>oclass</literal>/, and
1649 <literal>value</literal> fields are assumed to be set correctly -
1650 and returns a pointer to a the buffer as given by <literal>dst</literal>
1652 representation of the corresponding OID. The function returns
1653 NULL and the array dst is unchanged if a mapping couldn't place.
1654 The array <literal>dst</literal> should be at least of size
1655 <literal>OID_SIZE</literal>.
1659 The <function>oid_ent_to_oid()</function> function can be used whenever
1660 you need to prepare a PDU containing one or more OIDs. The separation of
1661 the <literal>protocol</literal> element from the remainder of the
1662 OID-description makes it simple to write applications that can
1663 communicate with either Z39.50 or OSI SR-based applications.
1671 oid_value oid_getvalbyname(const char *name);
1675 takes as argument a mnemonic OID name, and returns the
1676 <literal>/value</literal> field of the first entry in the database that
1677 contains the given name in its <literal>desc</literal> field.
1681 Three utility functions are provided for translating OIDs'
1682 symbolic names (e.g. <literal>Usmarc</literal> into OID structures
1683 (int arrays) and strings containing the OID in dotted notation
1684 (e.g. <literal>1.2.840.10003.9.5.1</literal>). They are:
1688 int *oid_name_to_oid(oid_class oclass, const char *name, int *oid);
1689 char *oid_to_dotstring(const int *oid, char *oidbuf);
1690 char *oid_name_to_dotstring(oid_class oclass, const char *name, char *oidbuf);
1694 <literal>oid_name_to_oid()</literal>
1695 translates the specified symbolic <literal>name</literal>,
1696 interpreted as being of class <literal>oclass</literal>. (The
1697 class must be specified as many symbolic names exist within
1698 multiple classes - for example, <literal>Zthes</literal> is the
1699 symbolic name of an attribute set, a schema and a tag-set.) The
1700 sequence of integers representing the OID is written into the
1701 area <literal>oid</literal> provided by the caller; it is the
1702 caller's responsibility to ensure that this area is large enough
1703 to contain the translated OID. As a convenience, the address of
1704 the buffer (i.e. the value of <literal>oid</literal>) is
1708 <literal>oid_to_dotstring()</literal>
1709 Translates the int-array <literal>oid</literal> into a dotted
1710 string which is written into the area <literal>oidbuf</literal>
1711 supplied by the caller; it is the caller's responsibility to
1712 ensure that this area is large enough. The address of the buffer
1716 <literal>oid_name_to_dotstring()</literal>
1717 combines the previous two functions to derive a dotted string
1718 representing the OID specified by <literal>oclass</literal> and
1719 <literal>name</literal>, writing it into the buffer passed as
1720 <literal>oidbuf</literal> and returning its address.
1724 Finally, the module provides the following utility functions, whose
1725 meaning should be obvious:
1729 void oid_oidcpy(int *t, int *s);
1730 void oid_oidcat(int *t, int *s);
1731 int oid_oidcmp(int *o1, int *o2);
1732 int oid_oidlen(int *o);
1737 The OID module has been criticized - and perhaps rightly so
1738 - for needlessly abstracting the
1739 representation of OIDs. Other toolkits use a simple
1740 string-representation of OIDs with good results. In practice, we have
1741 found the interface comfortable and quick to work with, and it is a
1742 simple matter (for what it's worth) to create applications compatible
1743 with both ISO SR and Z39.50. Finally, the use of the
1744 <literal>/oident</literal> database is by no means mandatory.
1745 You can easily create your own system for representing OIDs, as long
1746 as it is compatible with the low-level integer-array representation
1753 <sect1 id="tools.nmem"><title>Nibble Memory</title>
1756 Sometimes when you need to allocate and construct a large,
1757 interconnected complex of structures, it can be a bit of a pain to
1758 release the associated memory again. For the structures describing the
1759 Z39.50 PDUs and related structures, it is convenient to use the
1760 memory-management system of the &odr; subsystem (see
1761 <link linkend="odr-use">Using ODR</link>). However, in some circumstances
1762 where you might otherwise benefit from using a simple nibble memory
1763 management system, it may be impractical to use
1764 <function>odr_malloc()</function> and <function>odr_reset()</function>.
1765 For this purpose, the memory manager which also supports the &odr;
1766 streams is made available in the NMEM module. The external interface
1767 to this module is given in the <filename>nmem.h</filename> file.
1771 The following prototypes are given:
1775 NMEM nmem_create(void);
1776 void nmem_destroy(NMEM n);
1777 void *nmem_malloc(NMEM n, int size);
1778 void nmem_reset(NMEM n);
1779 int nmem_total(NMEM n);
1780 void nmem_init(void);
1781 void nmem_exit(void);
1785 The <function>nmem_create()</function> function returns a pointer to a
1786 memory control handle, which can be released again by
1787 <function>nmem_destroy()</function> when no longer needed.
1788 The function <function>nmem_malloc()</function> allocates a block of
1789 memory of the requested size. A call to <function>nmem_reset()</function>
1790 or <function>nmem_destroy()</function> will release all memory allocated
1791 on the handle since it was created (or since the last call to
1792 <function>nmem_reset()</function>. The function
1793 <function>nmem_total()</function> returns the number of bytes currently
1794 allocated on the handle.
1798 The nibble memory pool is shared amongst threads. POSIX
1799 mutex'es and WIN32 Critical sections are introduced to keep the
1800 module thread safe. Function <function>nmem_init()</function>
1801 initializes the nibble memory library and it is called automatically
1802 the first time the <literal>YAZ.DLL</literal> is loaded. &yaz; uses
1803 function <function>DllMain</function> to achieve this. You should
1804 <emphasis>not</emphasis> call <function>nmem_init</function> or
1805 <function>nmem_exit</function> unless you're absolute sure what
1806 you're doing. Note that in previous &yaz; versions you'd have to call
1807 <function>nmem_init</function> yourself.
1813 <!-- Keep this comment at the end of the file
1818 sgml-minimize-attributes:nil
1819 sgml-always-quote-attributes:t
1822 sgml-parent-document: "yaz.xml"
1823 sgml-local-catalogs: nil
1824 sgml-namecase-general:t