1 <chapter id="tools"><title>Supporting Tools</title>
4 In support of the service API - primarily the ASN module, which
5 provides the pro-grammatic interface to the Z39.50 APDUs, &yaz; contains
6 a collection of tools that support the development of applications.
9 <sect1 id="tools.query"><title>Query Syntax Parsers</title>
12 Since the type-1 (RPN) query structure has no direct, useful string
13 representation, every origin application needs to provide some form of
14 mapping from a local query notation or representation to a
15 <token>Z_RPNQuery</token> structure. Some programmers will prefer to
16 construct the query manually, perhaps using
17 <function>odr_malloc()</function> to simplify memory management.
18 The &yaz; distribution includes three separate, query-generating tools
19 that may be of use to you.
22 <sect2 id="PQF"><title>Prefix Query Format</title>
25 Since RPN or reverse polish notation is really just a fancy way of
26 describing a suffix notation format (operator follows operands), it
27 would seem that the confusion is total when we now introduce a prefix
28 notation for RPN. The reason is one of simple laziness - it's somewhat
29 simpler to interpret a prefix format, and this utility was designed
30 for maximum simplicity, to provide a baseline representation for use
31 in simple test applications and scripting environments (like Tcl). The
32 demonstration client included with YAZ uses the PQF.
37 The PQF have been adopted by other parties developing Z39.50
38 software. It is often referred to as Prefix Query Notation
43 The PQF is defined by the pquery module in the YAZ library.
44 There are two sets of function that have similar behavior. First
45 set operates on a PQF parser handle, second set doesn't. First set
46 set of functions are more flexible than the second set. Second set
47 is obsolete and is only provided to ensure backwards compatibility.
50 First set of functions all operate on a PQF parser handle:
53 #include <yaz/pquery.h>
55 YAZ_PQF_Parser yaz_pqf_create(void);
57 void yaz_pqf_destroy(YAZ_PQF_Parser p);
59 Z_RPNQuery *yaz_pqf_parse(YAZ_PQF_Parser p, ODR o, const char *qbuf);
61 Z_AttributesPlusTerm *yaz_pqf_scan(YAZ_PQF_Parser p, ODR o,
62 Odr_oid **attributeSetId, const char *qbuf);
64 int yaz_pqf_error(YAZ_PQF_Parser p, const char **msg, size_t *off);
67 A PQF parser is created and destructed by functions
68 <function>yaz_pqf_create</function> and
69 <function>yaz_pqf_destroy</function> respectively.
70 Function <function>yaz_pqf_parse</function> parses query given
71 by string <literal>qbuf</literal>. If parsing was successful,
72 a Z39.50 RPN Query is returned which is created using ODR stream
73 <literal>o</literal>. If parsing failed, a NULL pointer is
75 Function <function>yaz_pqf_scan</function> takes a scan query in
76 <literal>qbuf</literal>. If parsing was successful, the function
77 returns attributes plus term pointer and modifies
78 <literal>attributeSetId</literal> to hold attribute set for the
79 scan request - both allocated using ODR stream <literal>o</literal>.
80 If parsing failed, yaz_pqf_scan returns a NULL pointer.
81 Error information for bad queries can be obtained by a call to
82 <function>yaz_pqf_error</function> which returns an error code and
83 modifies <literal>*msg</literal> to point to an error description,
84 and modifies <literal>*off</literal> to the offset within last
85 query were parsing failed.
88 The second set of functions are declared as follows:
91 #include <yaz/pquery.h>
93 Z_RPNQuery *p_query_rpn(ODR o, oid_proto proto, const char *qbuf);
95 Z_AttributesPlusTerm *p_query_scan(ODR o, oid_proto proto,
96 Odr_oid **attributeSetP, const char *qbuf);
98 int p_query_attset(const char *arg);
101 The function <function>p_query_rpn()</function> takes as arguments an
102 &odr; stream (see section <link linkend="odr">The ODR Module</link>)
103 to provide a memory source (the structure created is released on
104 the next call to <function>odr_reset()</function> on the stream), a
105 protocol identifier (one of the constants <token>PROTO_Z3950</token> and
106 <token>PROTO_SR</token>), an attribute set reference, and
107 finally a null-terminated string holding the query string.
110 If the parse went well, <function>p_query_rpn()</function> returns a
111 pointer to a <literal>Z_RPNQuery</literal> structure which can be
112 placed directly into a <literal>Z_SearchRequest</literal>.
113 If parsing failed, due to syntax error, a NULL pointer is returned.
116 The <literal>p_query_attset</literal> specifies which attribute set
117 to use if the query doesn't specify one by the
118 <literal>@attrset</literal> operator.
119 The <literal>p_query_attset</literal> returns 0 if the argument is a
120 valid attribute set specifier; otherwise the function returns -1.
124 The grammar of the PQF is as follows:
128 query ::= top-set query-struct.
130 top-set ::= [ '@attrset' string ]
132 query-struct ::= attr-spec | simple | complex | '@term' term-type query
134 attr-spec ::= '@attr' [ string ] string query-struct
136 complex ::= operator query-struct query-struct.
138 operator ::= '@and' | '@or' | '@not' | '@prox' proximity.
140 simple ::= result-set | term.
142 result-set ::= '@set' string.
146 proximity ::= exclusion distance ordered relation which-code unit-code.
148 exclusion ::= '1' | '0' | 'void'.
150 distance ::= integer.
152 ordered ::= '1' | '0'.
154 relation ::= integer.
156 which-code ::= 'known' | 'private' | integer.
158 unit-code ::= integer.
160 term-type ::= 'general' | 'numeric' | 'string' | 'oid' | 'datetime' | 'null'.
164 You will note that the syntax above is a fairly faithful
165 representation of RPN, except for the Attribute, which has been
166 moved a step away from the term, allowing you to associate one or more
167 attributes with an entire query structure. The parser will
168 automatically apply the given attributes to each term as required.
172 The @attr operator is followed by an attribute specification
173 (<literal>attr-spec</literal> above). The specification consists
174 of an optional attribute set, an attribute type-value pair and
175 a sub-query. The attribute type-value pair is packed in one string:
176 an attribute type, an equals sign, and an attribute value, like this:
177 <literal>@attr 1=1003</literal>.
178 The type is always an integer but the value may be either an
179 integer or a string (if it doesn't start with a digit character).
180 A string attribute-value is encoded as a Type-1 ``complex''
181 attribute with the list of values containing the single string
182 specified, and including no semantic indicators.
186 Version 3 of the Z39.50 specification defines various encoding of terms.
187 Use <literal>@term </literal> <replaceable>type</replaceable>
188 <replaceable>string</replaceable>,
189 where type is one of: <literal>general</literal>,
190 <literal>numeric</literal> or <literal>string</literal>
191 (for InternationalString).
192 If no term type has been given, the <literal>general</literal> form
193 is used. This is the only encoding allowed in both versions 2 and 3
194 of the Z39.50 standard.
197 <sect3 id="PQF-prox">
198 <title>Using Proximity Operators with PQF</title>
201 This is an advanced topic, describing how to construct
202 queries that make very specific requirements on the
203 relative location of their operands.
204 You may wish to skip this section and go straight to
205 <link linkend="pqf-examples">the example PQF queries</link>.
210 Most Z39.50 servers do not support proximity searching, or
211 support only a small subset of the full functionality that
212 can be expressed using the PQF proximity operator. Be
213 aware that the ability to <emphasis>express</emphasis> a
214 query in PQF is no guarantee that any given server will
215 be able to <emphasis>execute</emphasis> it.
221 The proximity operator <literal>@prox</literal> is a special
222 and more restrictive version of the conjunction operator
223 <literal>@and</literal>. Its semantics are described in
224 section 3.7.2 (Proximity) of Z39.50 the standard itself, which
225 can be read on-line at
226 <ulink url="&url.z39.50.proximity;"/>
229 In PQF, the proximity operation is represented by a sequence
232 @prox <replaceable>exclusion</replaceable> <replaceable>distance</replaceable> <replaceable>ordered</replaceable> <replaceable>relation</replaceable> <replaceable>which-code</replaceable> <replaceable>unit-code</replaceable>
234 in which the meanings of the parameters are as described in in
235 the standard, and they can take the following values:
237 <listitem><formalpara><title>exclusion</title><para>
238 0 = false (i.e. the proximity condition specified by the
239 remaining parameters must be satisfied) or
240 1 = true (the proximity condition specified by the
241 remaining parameters must <emphasis>not</emphasis> be
243 </para></formalpara></listitem>
244 <listitem><formalpara><title>distance</title><para>
245 An integer specifying the difference between the locations
246 of the operands: e.g. two adjacent words would have
247 distance=1 since their locations differ by one unit.
248 </para></formalpara></listitem>
249 <listitem><formalpara><title>ordered</title><para>
250 1 = ordered (the operands must occur in the order the
251 query specifies them) or
252 0 = unordered (they may appear in either order).
253 </para></formalpara></listitem>
254 <listitem><formalpara><title>relation</title><para>
255 Recognised values are
259 4 (greaterThanOrEqual),
262 </para></formalpara></listitem>
263 <listitem><formalpara><title>which-code</title><para>
264 <literal>known</literal>
267 (the unit-code parameter is taken from the well-known list
268 of alternatives described in below) or
269 <literal>private</literal>
272 (the unit-code paramater has semantics specific to an
273 out-of-band agreement such as a profile).
274 </para></formalpara></listitem>
275 <listitem><formalpara><title>unit-code</title><para>
276 If the which-code parameter is <literal>known</literal>
277 then the recognised values are
289 If which-code is <literal>private</literal> then the
290 acceptable values are determined by the profile.
291 </para></formalpara></listitem>
293 (The numeric values of the relation and well-known unit-code
294 parameters are taken straight from
295 <ulink url="&url.z39.50.proximity.asn1;"
296 >the ASN.1</ulink> of the proximity structure in the standard.)
300 <sect3 id="pqf-examples"><title>PQF queries</title>
302 <example id="example.pqf.simple.terms">
303 <title>PQF queries using simple terms</title>
312 <example id="pqf.example.pqf.boolean.operators">
313 <title>PQF boolean operators</title>
316 @or "dylan" "zimmerman"
318 @and @or dylan zimmerman when
320 @and when @or dylan zimmerman
324 <example id="example.pqf.result.sets">
325 <title>PQF references to result sets</title>
330 @and @set seta @set setb
334 <example id="example.pqf.attributes">
335 <title>Attributes for terms</title>
340 @attr 1=4 @attr 4=1 "self portrait"
342 @attrset exp1 @attr 1=1 CategoryList
344 @attr gils 1=2008 Copenhagen
346 @attr 1=/book/title computer
350 <example id="example.pqf.proximity">
351 <title>PQF Proximity queries</title>
354 @prox 0 3 1 2 k 2 dylan zimmerman
357 Here the parameters 0, 3, 1, 2, k and 2 represent exclusion,
358 distance, ordered, relation, which-code and unit-code, in that
362 exclusion = 0: the proximity condition must hold
365 distance = 3: the terms must be three units apart
368 ordered = 1: they must occur in the order they are specified
371 relation = 2: lessThanOrEqual (to the distance of 3 units)
374 which-code is ``known'', so the standard unit-codes are used
380 So the whole proximity query means that the words
381 <literal>dylan</literal> and <literal>zimmerman</literal> must
382 both occur in the record, in that order, differing in position
383 by three or fewer words (i.e. with two or fewer words between
384 them.) The query would find ``Bob Dylan, aka. Robert
385 Zimmerman'', but not ``Bob Dylan, born as Robert Zimmerman''
386 since the distance in this case is four.
390 <example id="example.pqf.search.term.type">
391 <title>PQF specification of search term type</title>
394 @term string "a UTF-8 string, maybe?"
398 <example id="example.pqf.mixed.queries">
399 <title>PQF mixed queries</title>
402 @or @and bob dylan @set Result-1
404 @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming"
406 @and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109
410 The last of these examples is a spatial search: in
411 <ulink url="http://www.gils.net/prof_v2.html#sec_7_4"
412 >the GILS attribute set</ulink>,
414 2038 indicates West Bounding Coordinate and
415 2030 indicates East Bounding Coordinate,
416 so the query is for areas extending from -114 degrees
417 to no more than -109 degrees.
424 <sect2 id="CCL"><title>CCL</title>
427 Not all users enjoy typing in prefix query structures and numerical
428 attribute values, even in a minimalistic test client. In the library
429 world, the more intuitive Common Command Language - CCL (ISO 8777)
430 has enjoyed some popularity - especially before the widespread
431 availability of graphical interfaces. It is still useful in
432 applications where you for some reason or other need to provide a
433 symbolic language for expressing boolean query structures.
436 <sect3 id="ccl.syntax">
437 <title>CCL Syntax</title>
440 The CCL parser obeys the following grammar for the FIND argument.
441 The syntax is annotated by in the lines prefixed by
442 <literal>--</literal>.
446 CCL-Find ::= CCL-Find Op Elements
449 Op ::= "and" | "or" | "not"
450 -- The above means that Elements are separated by boolean operators.
452 Elements ::= '(' CCL-Find ')'
455 | Qualifiers Relation Terms
456 | Qualifiers Relation '(' CCL-Find ')'
457 | Qualifiers '=' string '-' string
458 -- Elements is either a recursive definition, a result set reference, a
459 -- list of terms, qualifiers followed by terms, qualifiers followed
460 -- by a recursive definition or qualifiers in a range (lower - upper).
462 Set ::= 'set' = string
463 -- Reference to a result set
465 Terms ::= Terms Prox Term
467 -- Proximity of terms.
471 -- This basically means that a term may include a blank
473 Qualifiers ::= Qualifiers ',' string
475 -- Qualifiers is a list of strings separated by comma
477 Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<'
478 -- Relational operators. This really doesn't follow the ISO8777
482 -- Proximity operator
486 <example id="example.ccl.queries">
487 <title>CCL queries</title>
489 The following queries are all valid:
501 (dylan and bob) or set=1
511 Assuming that the qualifiers <literal>ti</literal>,
512 <literal>au</literal>
513 and <literal>date</literal> are defined we may use:
519 au=(bob dylan and slow train coming)
521 date>1980 and (ti=((self portrait)))
527 <sect3 id="ccl.qualifiers">
528 <title>CCL Qualifiers</title>
531 Qualifiers are used to direct the search to a particular searchable
532 index, such as title (ti) and author indexes (au). The CCL standard
533 itself doesn't specify a particular set of qualifiers, but it does
534 suggest a few short-hand notations. You can customize the CCL parser
535 to support a particular set of qualifiers to reflect the current target
536 profile. Traditionally, a qualifier would map to a particular
537 use-attribute within the BIB-1 attribute set. It is also
538 possible to set other attributes, such as the structure
543 A CCL profile is a set of predefined CCL qualifiers that may be
544 read from a file or set in the CCL API.
545 The YAZ client reads its CCL qualifiers from a file named
546 <filename>default.bib</filename>. There are four types of
547 lines in a CCL profile: qualifier specification,
548 qualifier alias, comments and directives.
550 <sect4 id="ccl.qualifier.specification">
551 <title>Qualifier specification</title>
553 A qualifier specification is of the form:
557 <replaceable>qualifier-name</replaceable>
558 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable>
559 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable> ...
563 where <replaceable>qualifier-name</replaceable> is the name of the
564 qualifier to be used (eg. <literal>ti</literal>),
565 <replaceable>type</replaceable> is attribute type in the attribute
566 set (Bib-1 is used if no attribute set is given) and
567 <replaceable>val</replaceable> is attribute value.
568 The <replaceable>type</replaceable> can be specified as an
569 integer or as it be specified either as a single-letter:
570 <literal>u</literal> for use,
571 <literal>r</literal> for relation,<literal>p</literal> for position,
572 <literal>s</literal> for structure,<literal>t</literal> for truncation
573 or <literal>c</literal> for completeness.
574 The attributes for the special qualifier name <literal>term</literal>
575 are used when no CCL qualifier is given in a query.
576 <table id="ccl.common.bib1.attributes">
577 <title>Common Bib-1 attributes</title>
579 <colspec colwidth="2*" colname="type"></colspec>
580 <colspec colwidth="9*" colname="description"></colspec>
584 <entry>Description</entry>
589 <entry><literal>u=</literal><replaceable>value</replaceable></entry>
591 Use attribute (1). Common use attributes are
592 1 Personal-name, 4 Title, 7 ISBN, 8 ISSN, 30 Date,
593 62 Subject, 1003 Author), 1016 Any. Specify value
599 <entry><literal>r=</literal><replaceable>value</replaceable></entry>
601 Relation attribute (2). Common values are
602 1 <, 2 <=, 3 =, 4 >=, 5 >, 6 <>,
603 100 phonetic, 101 stem, 102 relevance, 103 always matches.
608 <entry><literal>p=</literal><replaceable>value</replaceable></entry>
610 Position attribute (3). Values: 1 first in field, 2
611 first in any subfield, 3 any position in field.
616 <entry><literal>s=</literal><replaceable>value</replaceable></entry>
618 Structure attribute (4). Values: 1 phrase, 2 word,
619 3 key, 4 year, 5 date, 6 word list, 100 date (un),
620 101 name (norm), 102 name (un), 103 structure, 104 urx,
621 105 free-form-text, 106 document-text, 107 local-number,
622 108 string, 109 numeric string.
627 <entry><literal>t=</literal><replaceable>value</replaceable></entry>
629 Truncation attribute (5). Values: 1 right, 2 left,
630 3 left& right, 100 none, 101 process #, 102 regular-1,
631 103 regular-2, 104 CCL.
636 <entry><literal>c=</literal><replaceable>value</replaceable></entry>
638 Completeness attribute (6). Values: 1 incomplete subfield,
639 2 complete subfield, 3 complete field.
648 Refer to <xref linkend="bib1"/> or the complete
649 <ulink url="&url.z39.50.attset.bib1;">list of Bib-1 attributes</ulink>
652 It is also possible to specify non-numeric attribute values,
653 which are used in combination with certain types.
654 The special combinations are:
656 <table id="ccl.special.attribute.combos">
657 <title>Special attribute combos</title>
659 <colspec colwidth="2*" colname="name"></colspec>
660 <colspec colwidth="9*" colname="description"></colspec>
664 <entry>Description</entry>
669 <entry><literal>s=pw</literal></entry><entry>
670 The structure is set to either word or phrase depending
671 on the number of tokens in a term (phrase-word).
675 <entry><literal>s=al</literal></entry><entry>
676 Each token in the term is ANDed. (and-list).
677 This does not set the structure at all.
681 <row><entry><literal>s=ol</literal></entry><entry>
682 Each token in the term is ORed. (or-list).
683 This does not set the structure at all.
687 <row><entry><literal>s=ag</literal></entry><entry>
688 Tokens that appears as phrases (with blank in them) gets
689 structure phrase attached. Tokens that appers as words
690 gets structure phrase attached. Phrases and words are
691 ANDed. This is a variant of s=al and s=pw, with the main
692 difference that words are not split (with operator AND)
693 but instead kept in one RPN token. This facility appeared
698 <row><entry><literal>r=o</literal></entry><entry>
699 Allows ranges and the operators greather-than, less-than, ...
701 This sets Bib-1 relation attribute accordingly (relation
702 ordered). A query construct is only treated as a range if
703 dash is used and that is surrounded by white-space. So
704 <literal>-1980</literal> is treated as term
705 <literal>"-1980"</literal> not <literal><= 1980</literal>.
706 If <literal>- 1980</literal> is used, however, that is
711 <row><entry><literal>r=r</literal></entry><entry>
712 Similar to <literal>r=o</literal> but assumes that terms
713 are non-negative (not prefixed with <literal>-</literal>).
714 Thus, a dash will always be treated as a range.
715 The construct <literal>1980-1990</literal> is
716 treated as a range with <literal>r=r</literal> but as a
717 single term <literal>"1980-1990"</literal> with
718 <literal>r=o</literal>. The special attribute
719 <literal>r=r</literal> is available in YAZ 2.0.24 or later.
723 <row><entry><literal>t=l</literal></entry><entry>
724 Allows term to be left-truncated.
725 If term is of the form <literal>?x</literal>, the resulting
726 Type-1 term is <literal>x</literal> and truncation is left.
730 <row><entry><literal>t=r</literal></entry><entry>
731 Allows term to be right-truncated.
732 If term is of the form <literal>x?</literal>, the resulting
733 Type-1 term is <literal>x</literal> and truncation is right.
737 <row><entry><literal>t=n</literal></entry><entry>
738 If term is does not include <literal>?</literal>, the
739 truncation attribute is set to none (100).
743 <row><entry><literal>t=b</literal></entry><entry>
744 Allows term to be both left&right truncated.
745 If term is of the form <literal>?x?</literal>, the
746 resulting term is <literal>x</literal> and trunctation is
747 set to both left&right.
751 <row><entry><literal>t=x</literal></entry><entry>
752 Allows masking anywhere in a term, thus fully supporting
753 # (mask one character) and ? (zero or more of any).
754 If masking is used, trunction is set to 102 (regexp-1 in term)
755 and the term is converted accordingly to a regular expression.
759 <row><entry><literal>t=z</literal></entry><entry>
760 Allows masking anywhere in a term, thus fully supporting
761 # (mask one character) and ? (zero or more of any).
762 If masking is used, trunction is set to 104 (Z39.58 in term)
763 and the term is converted accordingly to Z39.58 masking term -
764 actually the same truncation as CCL itself.
772 <example id="example.ccl.profile"><title>CCL profile</title>
774 Consider the following definition:
785 <literal>ti</literal> and <literal>au</literal> both set
786 structure attribute to phrase (s=1).
787 <literal>ti</literal>
788 sets the use-attribute to 4. <literal>au</literal> sets the
790 When no qualifiers are used in the query the structure-attribute is
791 set to free-form-text (105) (rule for <literal>term</literal>).
792 The <literal>date</literal> sets the relation attribute to
793 the relation used in the CCL query and sets the use attribute
797 You can combine attributes. To Search for "ranked title" you
800 ti,ranked=knuth computer
802 which will set relation=ranked, use=title, structure=phrase.
809 is a valid query. But
817 <sect4 id="ccl.qualifier.alias">
818 <title>Qualifier alias</title>
820 A qualifier alias is of the form:
823 <replaceable>q</replaceable>
824 <replaceable>q1</replaceable> <replaceable>q2</replaceable> ..
827 which declares <replaceable>q</replaceable> to
828 be an alias for <replaceable>q1</replaceable>,
829 <replaceable>q2</replaceable>... such that the CCL
830 query <replaceable>q=x</replaceable> is equivalent to
831 <replaceable>q1=x or q2=x or ...</replaceable>.
835 <sect4 id="ccl.comments">
836 <title>Comments</title>
838 Lines with white space or lines that begin with
839 character <literal>#</literal> are treated as comments.
843 <sect4 id="ccl.directives">
844 <title>Directives</title>
846 Directive specifications takes the form
848 <para><literal>@</literal><replaceable>directive</replaceable> <replaceable>value</replaceable>
850 <table id="ccl.directives.table">
851 <title>CCL directives</title>
853 <colspec colwidth="2*" colname="name"></colspec>
854 <colspec colwidth="8*" colname="description"></colspec>
855 <colspec colwidth="1*" colname="default"></colspec>
859 <entry>Description</entry>
860 <entry>Default</entry>
865 <entry>truncation</entry>
866 <entry>Truncation character</entry>
867 <entry><literal>?</literal></entry>
871 <entry>Specifies how multiple fields are to be
872 combined. There are two modes: <literal>or</literal>:
873 multiple qualifier fields are ORed,
874 <literal>merge</literal>: attributes for the qualifier
875 fields are merged and assigned to one term.
877 <entry><literal>merge</literal></entry>
881 <entry>Specifies if CCL operators and qualifiers should be
882 compared with case sensitivity or not. Specify 1 for
883 case sensitive; 0 for case insensitive.</entry>
884 <entry><literal>1</literal></entry>
889 <entry>Specifies token for CCL operator AND.</entry>
890 <entry><literal>and</literal></entry>
895 <entry>Specifies token for CCL operator OR.</entry>
896 <entry><literal>or</literal></entry>
901 <entry>Specifies token for CCL operator NOT.</entry>
902 <entry><literal>not</literal></entry>
907 <entry>Specifies token for CCL operator SET.</entry>
908 <entry><literal>set</literal></entry>
916 <title>CCL API</title>
918 All public definitions can be found in the header file
919 <filename>ccl.h</filename>. A profile identifier is of type
920 <literal>CCL_bibset</literal>. A profile must be created with the call
921 to the function <function>ccl_qual_mk</function> which returns a profile
922 handle of type <literal>CCL_bibset</literal>.
926 To read a file containing qualifier definitions the function
927 <function>ccl_qual_file</function> may be convenient. This function
928 takes an already opened <literal>FILE</literal> handle pointer as
929 argument along with a <literal>CCL_bibset</literal> handle.
933 To parse a simple string with a FIND query use the function
936 struct ccl_rpn_node *ccl_find_str(CCL_bibset bibset, const char *str,
937 int *error, int *pos);
940 which takes the CCL profile (<literal>bibset</literal>) and query
941 (<literal>str</literal>) as input. Upon successful completion the RPN
942 tree is returned. If an error occur, such as a syntax error, the integer
943 pointed to by <literal>error</literal> holds the error code and
944 <literal>pos</literal> holds the offset inside query string in which
949 An English representation of the error may be obtained by calling
950 the <literal>ccl_err_msg</literal> function. The error codes are
951 listed in <filename>ccl.h</filename>.
955 To convert the CCL RPN tree (type
956 <literal>struct ccl_rpn_node *</literal>)
957 to the Z_RPNQuery of YAZ the function <function>ccl_rpn_query</function>
958 must be used. This function which is part of YAZ is implemented in
959 <filename>yaz-ccl.c</filename>.
960 After calling this function the CCL RPN tree is probably no longer
961 needed. The <literal>ccl_rpn_delete</literal> destroys the CCL RPN tree.
965 A CCL profile may be destroyed by calling the
966 <function>ccl_qual_rm</function> function.
970 The token names for the CCL operators may be changed by setting the
971 globals (all type <literal>char *</literal>)
972 <literal>ccl_token_and</literal>, <literal>ccl_token_or</literal>,
973 <literal>ccl_token_not</literal> and <literal>ccl_token_set</literal>.
974 An operator may have aliases, i.e. there may be more than one name for
975 the operator. To do this, separate each alias with a space character.
979 <sect2 id="cql"><title>CQL</title>
981 <ulink url="&url.cql;">CQL</ulink>
982 - Common Query Language - was defined for the
983 <ulink url="&url.sru;">SRU</ulink> protocol.
984 In many ways CQL has a similar syntax to CCL.
985 The objective of CQL is different. Where CCL aims to be
986 an end-user language, CQL is <emphasis>the</emphasis> protocol
987 query language for SRU.
991 If you are new to CQL, read the
992 <ulink url="&url.cql.intro;">Gentle Introduction</ulink>.
996 The CQL parser in &yaz; provides the following:
1000 It parses and validates a CQL query.
1005 It generates a C structure that allows you to convert
1006 a CQL query to some other query language, such as SQL.
1011 The parser converts a valid CQL query to PQF, thus providing a
1012 way to use CQL for both SRU servers and Z39.50 targets at the
1018 The parser converts CQL to
1019 <ulink url="&url.xcql;">XCQL</ulink>.
1020 XCQL is an XML representation of CQL.
1021 XCQL is part of the SRU specification. However, since SRU
1022 supports CQL only, we don't expect XCQL to be widely used.
1023 Furthermore, CQL has the advantage over XCQL that it is
1029 <sect3 id="cql.parsing"><title>CQL parsing</title>
1031 A CQL parser is represented by the <literal>CQL_parser</literal>
1032 handle. Its contents should be considered &yaz; internal (private).
1034 #include <yaz/cql.h>
1036 typedef struct cql_parser *CQL_parser;
1038 CQL_parser cql_parser_create(void);
1039 void cql_parser_destroy(CQL_parser cp);
1041 A parser is created by <function>cql_parser_create</function> and
1042 is destroyed by <function>cql_parser_destroy</function>.
1045 To parse a CQL query string, the following function
1048 int cql_parser_string(CQL_parser cp, const char *str);
1050 A CQL query is parsed by the <function>cql_parser_string</function>
1051 which takes a query <parameter>str</parameter>.
1052 If the query was valid (no syntax errors), then zero is returned;
1053 otherwise -1 is returned to indicate a syntax error.
1057 int cql_parser_stream(CQL_parser cp,
1058 int (*getbyte)(void *client_data),
1059 void (*ungetbyte)(int b, void *client_data),
1062 int cql_parser_stdio(CQL_parser cp, FILE *f);
1064 The functions <function>cql_parser_stream</function> and
1065 <function>cql_parser_stdio</function> parses a CQL query
1066 - just like <function>cql_parser_string</function>.
1067 The only difference is that the CQL query can be
1068 fed to the parser in different ways.
1069 The <function>cql_parser_stream</function> uses a generic
1070 byte stream as input. The <function>cql_parser_stdio</function>
1071 uses a <literal>FILE</literal> handle which is opened for reading.
1075 <sect3 id="cql.tree"><title>CQL tree</title>
1077 The the query string is valid, the CQL parser
1078 generates a tree representing the structure of the
1083 struct cql_node *cql_parser_result(CQL_parser cp);
1085 <function>cql_parser_result</function> returns the
1086 a pointer to the root node of the resulting tree.
1089 Each node in a CQL tree is represented by a
1090 <literal>struct cql_node</literal>.
1091 It is defined as follows:
1093 #define CQL_NODE_ST 1
1094 #define CQL_NODE_BOOL 2
1095 #define CQL_NODE_SORT 3
1105 struct cql_node *modifiers;
1109 struct cql_node *left;
1110 struct cql_node *right;
1111 struct cql_node *modifiers;
1115 struct cql_node *next;
1116 struct cql_node *modifiers;
1117 struct cql_node *search;
1122 There are three node types: search term (ST), boolean (BOOL)
1124 A modifier is treated as a search term too.
1127 The search term node has five members:
1131 <literal>index</literal>: index for search term.
1132 If an index is unspecified for a search term,
1133 <literal>index</literal> will be NULL.
1138 <literal>index_uri</literal>: index URi for search term
1139 or NULL if none could be resolved for the index.
1144 <literal>term</literal>: the search term itself.
1149 <literal>relation</literal>: relation for search term.
1154 <literal>relation_uri</literal>: relation URI for search term.
1159 <literal>modifiers</literal>: relation modifiers for search
1160 term. The <literal>modifiers</literal> list itself of cql_nodes
1161 each of type <literal>ST</literal>.
1168 The boolean node represents <literal>and</literal>,
1169 <literal>or</literal>, <literal>not</literal> +
1174 <literal>left</literal> and <literal>right</literal>: left
1175 - and right operand respectively.
1180 <literal>modifiers</literal>: proximity arguments.
1187 The sort node represents both the SORTBY clause.
1191 <sect3 id="cql.to.pqf"><title>CQL to PQF conversion</title>
1193 Conversion to PQF (and Z39.50 RPN) is tricky by the fact
1194 that the resulting RPN depends on the Z39.50 target
1195 capabilities (combinations of supported attributes).
1196 In addition, the CQL and SRU operates on index prefixes
1197 (URI or strings), whereas the RPN uses Object Identifiers
1201 The CQL library of &yaz; defines a <literal>cql_transform_t</literal>
1202 type. It represents a particular mapping between CQL and RPN.
1203 This handle is created and destroyed by the functions:
1205 cql_transform_t cql_transform_open_FILE (FILE *f);
1206 cql_transform_t cql_transform_open_fname(const char *fname);
1207 void cql_transform_close(cql_transform_t ct);
1209 The first two functions create a tranformation handle from
1210 either an already open FILE or from a filename respectively.
1213 The handle is destroyed by <function>cql_transform_close</function>
1214 in which case no further reference of the handle is allowed.
1217 When a <literal>cql_transform_t</literal> handle has been created
1218 you can convert to RPN.
1220 int cql_transform_buf(cql_transform_t ct,
1221 struct cql_node *cn, char *out, int max);
1223 This function converts the CQL tree <literal>cn</literal>
1224 using handle <literal>ct</literal>.
1225 For the resulting PQF, you supply a buffer <literal>out</literal>
1226 which must be able to hold at at least <literal>max</literal>
1230 If conversion failed, <function>cql_transform_buf</function>
1231 returns a non-zero SRU error code; otherwise zero is returned
1232 (conversion successful). The meanings of the numeric error
1233 codes are listed in the SRU specifications at
1234 <ulink url="&url.sru.diagnostics.list;"/>
1237 If conversion fails, more information can be obtained by calling
1239 int cql_transform_error(cql_transform_t ct, char **addinfop);
1241 This function returns the most recently returned numeric
1242 error-code and sets the string-pointer at
1243 <literal>*addinfop</literal> to point to a string containing
1244 additional information about the error that occurred: for
1245 example, if the error code is 15 (``Illegal or unsupported context
1246 set''), the additional information is the name of the requested
1247 context set that was not recognised.
1250 The SRU error-codes may be translated into brief human-readable
1251 error messages using
1253 const char *cql_strerror(int code);
1257 If you wish to be able to produce a PQF result in a different
1258 way, there are two alternatives.
1260 void cql_transform_pr(cql_transform_t ct,
1261 struct cql_node *cn,
1262 void (*pr)(const char *buf, void *client_data),
1265 int cql_transform_FILE(cql_transform_t ct,
1266 struct cql_node *cn, FILE *f);
1268 The former function produces output to a user-defined
1269 output stream. The latter writes the result to an already
1270 open <literal>FILE</literal>.
1273 <sect3 id="cql.to.rpn">
1274 <title>Specification of CQL to RPN mappings</title>
1276 The file supplied to functions
1277 <function>cql_transform_open_FILE</function>,
1278 <function>cql_transform_open_fname</function> follows
1279 a structure found in many Unix utilities.
1280 It consists of mapping specifications - one per line.
1281 Lines starting with <literal>#</literal> are ignored (comments).
1284 Each line is of the form
1286 <replaceable>CQL pattern</replaceable><literal> = </literal> <replaceable> RPN equivalent</replaceable>
1290 An RPN pattern is a simple attribute list. Each attribute pair
1293 [<replaceable>set</replaceable>] <replaceable>type</replaceable><literal>=</literal><replaceable>value</replaceable>
1295 The attribute <replaceable>set</replaceable> is optional.
1296 The <replaceable>type</replaceable> is the attribute type,
1297 <replaceable>value</replaceable> the attribute value.
1300 The character <literal>*</literal> (asterisk) has special meaning
1301 when used in the RPN pattern.
1302 Each occurrence of <literal>*</literal> is substituted with the
1303 CQL matching name (index, relation, qualifier etc).
1304 This facility can be used to copy a CQL name verbatim to the RPN result.
1307 The following CQL patterns are recognized:
1309 <varlistentry><term>
1310 <literal>index.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1314 This pattern is invoked when a CQL index, such as
1315 dc.title is converted. <replaceable>set</replaceable>
1316 and <replaceable>name</replaceable> are the context set and index
1318 Typically, the RPN specifies an equivalent use attribute.
1321 For terms not bound by an index the pattern
1322 <literal>index.cql.serverChoice</literal> is used.
1323 Here, the prefix <literal>cql</literal> is defined as
1324 <literal>http://www.loc.gov/zing/cql/cql-indexes/v1.0/</literal>.
1325 If this pattern is not defined, the mapping will fail.
1329 <literal>index.</literal><replaceable>set</replaceable><literal>.*</literal>
1330 is used when no other index pattern is matched.
1334 <varlistentry><term>
1335 <literal>qualifier.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1340 For backwards compatibility, this is recognised as a synonym of
1341 <literal>index.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1345 <varlistentry><term>
1346 <literal>relation.</literal><replaceable>relation</replaceable>
1350 This pattern specifies how a CQL relation is mapped to RPN.
1351 <replaceable>pattern</replaceable> is name of relation
1352 operator. Since <literal>=</literal> is used as
1353 separator between CQL pattern and RPN, CQL relations
1354 including <literal>=</literal> cannot be
1355 used directly. To avoid a conflict, the names
1356 <literal>ge</literal>,
1357 <literal>eq</literal>,
1358 <literal>le</literal>,
1359 must be used for CQL operators, greater-than-or-equal,
1360 equal, less-than-or-equal respectively.
1361 The RPN pattern is supposed to include a relation attribute.
1364 For terms not bound by a relation, the pattern
1365 <literal>relation.scr</literal> is used. If the pattern
1366 is not defined, the mapping will fail.
1369 The special pattern, <literal>relation.*</literal> is used
1370 when no other relation pattern is matched.
1375 <varlistentry><term>
1376 <literal>relationModifier.</literal><replaceable>mod</replaceable>
1380 This pattern specifies how a CQL relation modifier is mapped to RPN.
1381 The RPN pattern is usually a relation attribute.
1386 <varlistentry><term>
1387 <literal>structure.</literal><replaceable>type</replaceable>
1391 This pattern specifies how a CQL structure is mapped to RPN.
1392 Note that this CQL pattern is somewhat to similar to
1393 CQL pattern <literal>relation</literal>.
1394 The <replaceable>type</replaceable> is a CQL relation.
1397 The pattern, <literal>structure.*</literal> is used
1398 when no other structure pattern is matched.
1399 Usually, the RPN equivalent specifies a structure attribute.
1404 <varlistentry><term>
1405 <literal>position.</literal><replaceable>type</replaceable>
1409 This pattern specifies how the anchor (position) of
1410 CQL is mapped to RPN.
1411 The <replaceable>type</replaceable> is one
1412 of <literal>first</literal>, <literal>any</literal>,
1413 <literal>last</literal>, <literal>firstAndLast</literal>.
1416 The pattern, <literal>position.*</literal> is used
1417 when no other position pattern is matched.
1422 <varlistentry><term>
1423 <literal>set.</literal><replaceable>prefix</replaceable>
1427 This specification defines a CQL context set for a given prefix.
1428 The value on the right hand side is the URI for the set -
1429 <emphasis>not</emphasis> RPN. All prefixes used in
1430 index patterns must be defined this way.
1435 <varlistentry><term>
1436 <literal>set</literal>
1440 This specification defines a default CQL context set for index names.
1441 The value on the right hand side is the URI for the set.
1448 <example id="example.cql.to.rpn.mapping">
1449 <title>CQL to RPN mapping file</title>
1451 This simple file defines two context sets, three indexes and three
1452 relations, a position pattern and a default structure.
1454 <programlisting><![CDATA[
1455 set.cql = http://www.loc.gov/zing/cql/context-sets/cql/v1.1/
1456 set.dc = http://www.loc.gov/zing/cql/dc-indexes/v1.0/
1458 index.cql.serverChoice = 1=1016
1459 index.dc.title = 1=4
1460 index.dc.subject = 1=21
1466 position.any = 3=3 6=1
1472 With the mappings above, the CQL query
1476 is converted to the PQF:
1478 @attr 1=1016 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "computer"
1480 by rules <literal>index.cql.serverChoice</literal>,
1481 <literal>relation.scr</literal>, <literal>structure.*</literal>,
1482 <literal>position.any</literal>.
1489 is rejected, since <literal>position.right</literal> is
1495 >my = "http://www.loc.gov/zing/cql/dc-indexes/v1.0/" my.title = x
1499 @attr 1=4 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "x"
1503 <example id="example.cql.to.rpn.string">
1504 <title>CQL to RPN string attributes</title>
1506 In this example we allow any index to be passed to RPN as
1509 <programlisting><![CDATA[
1510 # Identifiers for prefixes used in this file. (index.*)
1511 set.cql = info:srw/cql-context-set/1/cql-v1.1
1512 set.rpn = http://bogus/rpn
1513 set = http://bogus/rpn
1515 # The default index when none is specified by the query
1516 index.cql.serverChoice = 1=any
1525 The <literal>http://bogus/rpn</literal> context set is also the default
1526 so we can make queries such as
1530 which is converted to
1532 @attr 2=3 @attr 4=1 @attr 3=3 @attr 1=title "a"
1536 <example id="example.cql.to.rpn.bathprofile">
1537 <title>CQL to RPN using Bath Profile</title>
1539 The file <filename>etc/pqf.properties</filename> has mappings from
1540 the Bath Profile and Dublin Core to RPN.
1541 If YAZ is installed as a package it's usually located
1542 in <filename>/usr/share/yaz/etc</filename> and part of the
1543 development package, such as <literal>libyaz-dev</literal>.
1547 <sect3 id="cql.xcql"><title>CQL to XCQL conversion</title>
1549 Conversion from CQL to XCQL is trivial and does not
1550 require a mapping to be defined.
1551 There three functions to choose from depending on the
1552 way you wish to store the resulting output (XML buffer
1555 int cql_to_xml_buf(struct cql_node *cn, char *out, int max);
1556 void cql_to_xml(struct cql_node *cn,
1557 void (*pr)(const char *buf, void *client_data),
1559 void cql_to_xml_stdio(struct cql_node *cn, FILE *f);
1561 Function <function>cql_to_xml_buf</function> converts
1562 to XCQL and stores result in a user supplied buffer of a given
1566 <function>cql_to_xml</function> writes the result in
1567 a user defined output stream.
1568 <function>cql_to_xml_stdio</function> writes to a
1572 <sect3 id="rpn.to.cql">
1573 <title>PQF to CQL conversion</title>
1575 Conversion from PQF to CQL is offered by the two functions shown
1576 below. The former uses a generic stream for result. The latter
1577 puts result in a WRBUF (string container).
1579 #include <yaz/rpn2cql.h>
1581 int cql_transform_rpn2cql_stream(cql_transform_t ct,
1582 void (*pr)(const char *buf, void *client_data),
1586 int cql_transform_rpn2cql_wrbuf(cql_transform_t ct,
1590 The configuration is the same as used in CQL to PQF conversions.
1595 <sect1 id="tools.oid"><title>Object Identifiers</title>
1598 The basic YAZ representation of an OID is an array of integers,
1599 terminated with the value -1. This integer is of type
1600 <literal>Odr_oid</literal>.
1603 Fundamental OID operations and the type <literal>Odr_oid</literal>
1604 are defined in <filename>yaz/oid_util.h</filename>.
1607 An OID can either be declared as a automatic variable or it can
1608 allocated using the memory utilities or ODR/NMEM. It's
1609 guaranteed that an OID can fit in <literal>OID_SIZE</literal> integers.
1611 <example id="tools.oid.bib1.1"><title>Create OID on stack</title>
1613 We can create an OID for the Bib-1 attribute set with:
1615 Odr_oid bib1[OID_SIZE];
1627 And OID may also be filled from a string-based representation using
1628 dots (.). This is achieved by function
1630 int oid_dotstring_to_oid(const char *name, Odr_oid *oid);
1632 This functions returns 0 if name could be converted; -1 otherwise.
1634 <example id="tools.oid.bib1.2"><title>Using oid_oiddotstring_to_oid</title>
1636 We can fill the Bib-1 attribute set OID easier with:
1638 Odr_oid bib1[OID_SIZE];
1639 oid_oiddotstring_to_oid("1.2.840.10003.3.1", bib1);
1644 We can also allocate an OID dynamically on a ODR stream with:
1646 Odr_oid *odr_getoidbystr(ODR o, const char *str);
1648 This creates an OID from string-based representation using dots.
1649 This function take an &odr; stream as parameter. This stream is used to
1650 allocate memory for the data elements, which is released on a
1651 subsequent call to <function>odr_reset()</function> on that stream.
1654 <example id="tools.oid.bib1.3"><title>Using odr_getoidbystr</title>
1656 We can create a OID for the Bib-1 attribute set with:
1658 Odr_oid *bib1 = odr_getoidbystr(odr, "1.2.840.10003.3.1");
1666 char *oid_oid_to_dotstring(const Odr_oid *oid, char *oidbuf)
1668 does the reverse of <function>oid_oiddotstring_to_oid</function>. It
1669 converts an OID to the string-based representation using dots.
1670 The supplied char buffer <literal>oidbuf</literal> holds the resulting
1671 string and must be at least <literal>OID_STR_MAX</literal> in size.
1675 OIDs can be copied with <function>oid_oidcpy</function> which takes
1676 two OID lists as arguments. Alternativly, an OID copy can be allocated
1677 on a ODR stream with:
1679 Odr_oid *odr_oiddup(ODR odr, const Odr_oid *o);
1684 OIDs can be compared with <function>oid_oidcmp</function> which returns
1685 zero if the two OIDs provided are identical; non-zero otherwise.
1688 <sect2 id="tools.oid.database"><title>OID database</title>
1690 From YAZ version 3 and later, the oident system has been replaced
1691 by an OID database. OID database is a misnomer .. the old odient
1692 system was also a database.
1695 The OID database is really just a map between named Object Identifiers
1696 (string) and their OID raw equivalents. Most operations either
1697 convert from string to OID or other way around.
1700 Unfortunately, whenever we supply a string we must also specify the
1701 <emphasis>OID class</emphasis>. The class is necessary because some
1702 strings correspond to multiple OIDs. An example of such a string is
1703 <literal>Bib-1</literal> which may either be an attribute-set
1704 or a diagnostic-set.
1707 Applications using the YAZ database should include
1708 <filename>yaz/oid_db.h</filename>.
1711 A YAZ database handle is of type <literal>yaz_oid_db_t</literal>.
1712 Actually that's a pointer. You need not think deal with that.
1713 YAZ has a built-in database which can be considered "constant" for
1715 We can get hold that by using function <function>yaz_oid_std</function>.
1718 All functions with prefix <function>yaz_string_to_oid</function>
1719 converts from class + string to OID. We have variants of this
1720 operation due to different memory allocation strategies.
1723 All functions with prefix
1724 <function>yaz_oid_to_string</function> converts from OID to string
1728 <example id="tools.oid.bib1.4"><title>Create OID with YAZ DB</title>
1730 We can create an OID for the Bib-1 attribute set on the ODR stream
1734 yaz_string_to_oid_odr(yaz_oid_std(), CLASS_ATTSET, "Bib-1", odr);
1736 This is more complex than using <function>odr_getoidbystr</function>.
1737 You would only use <function>yaz_string_to_oid_odr</function> when the
1738 string (here Bib-1) is supplied by a user or configuration.
1743 <sect2 id="tools.oid.std"><title>Standard OIDs</title>
1746 All the object identifers in the standard OID database as returned
1747 by <function>yaz_oid_std</function> can referenced directly in a
1748 program as a constant OID.
1749 Each constant OID is prefixed with <literal>yaz_oid_</literal> -
1750 followed by OID class (lowercase) - then by OID name (normalized and
1754 See <xref linkend="list-oids"/> for list of all object identifiers
1756 These are declared in <filename>yaz/oid_std.h</filename> but are
1757 included by <filename>yaz/oid_db.h</filename> as well.
1760 <example id="tools.oid.bib1.5"><title>Use a built-in OID</title>
1762 We can allocate our own OID filled with the constant OID for
1765 Odr_oid *bib1 = odr_oiddup(o, yaz_oid_attset_bib1);
1771 <sect1 id="tools.nmem"><title>Nibble Memory</title>
1774 Sometimes when you need to allocate and construct a large,
1775 interconnected complex of structures, it can be a bit of a pain to
1776 release the associated memory again. For the structures describing the
1777 Z39.50 PDUs and related structures, it is convenient to use the
1778 memory-management system of the &odr; subsystem (see
1779 <xref linkend="odr.use"/>). However, in some circumstances
1780 where you might otherwise benefit from using a simple nibble memory
1781 management system, it may be impractical to use
1782 <function>odr_malloc()</function> and <function>odr_reset()</function>.
1783 For this purpose, the memory manager which also supports the &odr;
1784 streams is made available in the NMEM module. The external interface
1785 to this module is given in the <filename>nmem.h</filename> file.
1789 The following prototypes are given:
1793 NMEM nmem_create(void);
1794 void nmem_destroy(NMEM n);
1795 void *nmem_malloc(NMEM n, size_t size);
1796 void nmem_reset(NMEM n);
1797 size_t nmem_total(NMEM n);
1798 void nmem_init(void);
1799 void nmem_exit(void);
1803 The <function>nmem_create()</function> function returns a pointer to a
1804 memory control handle, which can be released again by
1805 <function>nmem_destroy()</function> when no longer needed.
1806 The function <function>nmem_malloc()</function> allocates a block of
1807 memory of the requested size. A call to <function>nmem_reset()</function>
1808 or <function>nmem_destroy()</function> will release all memory allocated
1809 on the handle since it was created (or since the last call to
1810 <function>nmem_reset()</function>. The function
1811 <function>nmem_total()</function> returns the number of bytes currently
1812 allocated on the handle.
1816 The nibble memory pool is shared amongst threads. POSIX
1817 mutex'es and WIN32 Critical sections are introduced to keep the
1818 module thread safe. Function <function>nmem_init()</function>
1819 initializes the nibble memory library and it is called automatically
1820 the first time the <literal>YAZ.DLL</literal> is loaded. &yaz; uses
1821 function <function>DllMain</function> to achieve this. You should
1822 <emphasis>not</emphasis> call <function>nmem_init</function> or
1823 <function>nmem_exit</function> unless you're absolute sure what
1824 you're doing. Note that in previous &yaz; versions you'd have to call
1825 <function>nmem_init</function> yourself.
1830 <sect1 id="tools.log"><title>Log</title>
1832 &yaz; has evolved a fairly complex log system which should be useful both
1833 for debugging &yaz; itself, debugging applications that use &yaz;, and for
1834 production use of those applications.
1837 The log functions are declared in header <filename>yaz/log.h</filename>
1838 and implemented in <filename>src/log.c</filename>.
1839 Due to name clash with syslog and some math utilities the logging
1840 interface has been modified as of YAZ 2.0.29. The obsolete interface
1841 is still available if in header file <filename>yaz/log.h</filename>.
1842 The key points of the interface are:
1845 void yaz_log(int level, const char *fmt, ...)
1847 void yaz_log_init(int level, const char *prefix, const char *name);
1848 void yaz_log_init_file(const char *fname);
1849 void yaz_log_init_level(int level);
1850 void yaz_log_init_prefix(const char *prefix);
1851 void yaz_log_time_format(const char *fmt);
1852 void yaz_log_init_max_size(int mx);
1854 int yaz_log_mask_str(const char *str);
1855 int yaz_log_module_level(const char *name);
1859 The reason for the whole log module is the <function>yaz_log</function>
1860 function. It takes a bitmask indicating the log levels, a
1861 <literal>printf</literal>-like format string, and a variable number of
1866 The <literal>log level</literal> is a bit mask, that says on which level(s)
1867 the log entry should be made, and optionally set some behaviour of the
1868 logging. In the most simple cases, it can be one of <literal>YLOG_FATAL,
1869 YLOG_DEBUG, YLOG_WARN, YLOG_LOG</literal>. Those can be combined with bits
1870 that modify the way the log entry is written:<literal>YLOG_ERRNO,
1871 YLOG_NOTIME, YLOG_FLUSH</literal>.
1872 Most of the rest of the bits are deprecated, and should not be used. Use
1873 the dynamic log levels instead.
1877 Applications that use &yaz;, should not use the LOG_LOG for ordinary
1878 messages, but should make use of the dynamic loglevel system. This consists
1879 of two parts, defining the loglevel and checking it.
1883 To define the log levels, the (main) program should pass a string to
1884 <function>yaz_log_mask_str</function> to define which log levels are to be
1885 logged. This string should be a comma-separated list of log level names,
1886 and can contain both hard-coded names and dynamic ones. The log level
1887 calculation starts with <literal>YLOG_DEFAULT_LEVEL</literal> and adds a bit
1888 for each word it meets, unless the word starts with a '-', in which case it
1889 clears the bit. If the string <literal>'none'</literal> is found,
1890 all bits are cleared. Typically this string comes from the command-line,
1891 often identified by <literal>-v</literal>. The
1892 <function>yaz_log_mask_str</function> returns a log level that should be
1893 passed to <function>yaz_log_init_level</function> for it to take effect.
1897 Each module should check what log bits it should be used, by calling
1898 <function>yaz_log_module_level</function> with a suitable name for the
1899 module. The name is cleared from a preceding path and an extension, if any,
1900 so it is quite possible to use <literal>__FILE__</literal> for it. If the
1901 name has been passed to <function>yaz_log_mask_str</function>, the routine
1902 returns a non-zero bitmask, which should then be used in consequent calls
1903 to yaz_log. (It can also be tested, so as to avoid unnecessary calls to
1904 yaz_log, in time-critical places, or when the log entry would take time
1909 Yaz uses the following dynamic log levels:
1910 <literal>server, session, request, requestdetail</literal> for the server
1912 <literal>zoom</literal> for the zoom client api.
1913 <literal>ztest</literal> for the simple test server.
1914 <literal>malloc, nmem, odr, eventl</literal> for internal debugging of yaz itself.
1915 Of course, any program using yaz is welcome to define as many new ones, as
1920 By default the log is written to stderr, but this can be changed by a call
1921 to <function>yaz_log_init_file</function> or
1922 <function>yaz_log_init</function>. If the log is directed to a file, the
1923 file size is checked at every write, and if it exceeds the limit given in
1924 <function>yaz_log_init_max_size</function>, the log is rotated. The
1925 rotation keeps one old version (with a <literal>.1</literal> appended to
1926 the name). The size defaults to 1GB. Setting it to zero will disable the
1931 A typical yaz-log looks like this
1932 13:23:14-23/11 yaz-ztest(1) [session] Starting session from tcp:127.0.0.1 (pid=30968)
1933 13:23:14-23/11 yaz-ztest(1) [request] Init from 'YAZ' (81) (ver 2.0.28) OK
1934 13:23:17-23/11 yaz-ztest(1) [request] Search Z: @attrset Bib-1 foo OK:7 hits
1935 13:23:22-23/11 yaz-ztest(1) [request] Present: [1] 2+2 OK 2 records returned
1936 13:24:13-23/11 yaz-ztest(1) [request] Close OK
1940 The log entries start with a time stamp. This can be omitted by setting the
1941 <literal>YLOG_NOTIME</literal> bit in the loglevel. This way automatic tests
1942 can be hoped to produce identical log files, that are easy to diff. The
1943 format of the time stamp can be set with
1944 <function>yaz_log_time_format</function>, which takes a format string just
1945 like <function>strftime</function>.
1949 Next in a log line comes the prefix, often the name of the program. For
1950 yaz-based servers, it can also contain the session number. Then
1951 comes one or more logbits in square brackets, depending on the logging
1952 level set by <function>yaz_log_init_level</function> and the loglevel
1953 passed to <function>yaz_log_init_level</function>. Finally comes the format
1954 string and additional values passed to <function>yaz_log</function>
1958 The log level <literal>YLOG_LOGLVL</literal>, enabled by the string
1959 <literal>loglevel</literal>, will log all the log-level affecting
1960 operations. This can come in handy if you need to know what other log
1961 levels would be useful. Grep the logfile for <literal>[loglevel]</literal>.
1965 The log system is almost independent of the rest of &yaz;, the only
1966 important dependence is of <filename>nmem</filename>, and that only for
1967 using the semaphore definition there.
1971 The dynamic log levels and log rotation were introduced in &yaz; 2.0.28. At
1972 the same time, the log bit names were changed from
1973 <literal>LOG_something</literal> to <literal>YLOG_something</literal>,
1974 to avoid collision with <filename>syslog.h</filename>.
1979 <sect1 id="marc"><title>MARC</title>
1982 YAZ provides a fast utility for working with MARC records.
1983 Early versions of the MARC utility only allowed decoding of ISO2709.
1984 Today the utility may both encode - and decode to a varity of formats.
1987 #include <yaz/marcdisp.h>
1989 /* create handler */
1990 yaz_marc_t yaz_marc_create(void);
1992 void yaz_marc_destroy(yaz_marc_t mt);
1994 /* set XML mode YAZ_MARC_LINE, YAZ_MARC_SIMPLEXML, ... */
1995 void yaz_marc_xml(yaz_marc_t mt, int xmlmode);
1996 #define YAZ_MARC_LINE 0
1997 #define YAZ_MARC_SIMPLEXML 1
1998 #define YAZ_MARC_OAIMARC 2
1999 #define YAZ_MARC_MARCXML 3
2000 #define YAZ_MARC_ISO2709 4
2001 #define YAZ_MARC_XCHANGE 5
2002 #define YAZ_MARC_CHECK 6
2003 #define YAZ_MARC_TURBOMARC 7
2005 /* supply iconv handle for character set conversion .. */
2006 void yaz_marc_iconv(yaz_marc_t mt, yaz_iconv_t cd);
2008 /* set debug level, 0=none, 1=more, 2=even more, .. */
2009 void yaz_marc_debug(yaz_marc_t mt, int level);
2011 /* decode MARC in buf of size bsize. Returns >0 on success; <=0 on failure.
2012 On success, result in *result with size *rsize. */
2013 int yaz_marc_decode_buf(yaz_marc_t mt, const char *buf, int bsize,
2014 const char **result, size_t *rsize);
2016 /* decode MARC in buf of size bsize. Returns >0 on success; <=0 on failure.
2017 On success, result in WRBUF */
2018 int yaz_marc_decode_wrbuf(yaz_marc_t mt, const char *buf,
2019 int bsize, WRBUF wrbuf);
2024 The synopsis is just a basic subset of all functionality. Refer
2025 to the actual header file <filename>marcdisp.h</filename> for
2030 A MARC conversion handle must be created by using
2031 <function>yaz_marc_create</function> and destroyed
2032 by calling <function>yaz_marc_destroy</function>.
2035 All other function operate on a <literal>yaz_marc_t</literal> handle.
2036 The output is specified by a call to <function>yaz_marc_xml</function>.
2037 The <literal>xmlmode</literal> must be one of
2040 <term>YAZ_MARC_LINE</term>
2043 A simple line-by-line format suitable for display but not
2044 recommend for further (machine) processing.
2050 <term>YAZ_MARC_MARCXML</term>
2053 <ulink url="&url.marcxml;">MARCXML</ulink>.
2059 <term>YAZ_MARC_ISO2709</term>
2062 ISO2709 (sometimes just referred to as "MARC").
2068 <term>YAZ_MARC_XCHANGE</term>
2071 <ulink url="&url.marcxchange;">MarcXchange</ulink>.
2077 <term>YAZ_MARC_CHECK</term>
2080 Pseudo format for validation only. Does not generate
2081 any real output except diagnostics.
2087 <term>YAZ_MARC_TURBOMARC</term>
2090 XML format with same semantics as MARCXML but more compact
2091 and geared towards fast processing with XSLT. Refer to
2092 <xref linkend="tools.turbomarc"/> for more information.
2100 The actual conversion functions are
2101 <function>yaz_marc_decode_buf</function> and
2102 <function>yaz_marc_decode_wrbuf</function> which decodes and encodes
2103 a MARC record. The former function operates on simple buffers, the
2104 stores the resulting record in a WRBUF handle (WRBUF is a simple string
2107 <example id="example.marc.display">
2108 <title>Display of MARC record</title>
2110 The following program snippet illustrates how the MARC API may
2111 be used to convert a MARC record to the line-by-line format:
2112 <programlisting><![CDATA[
2113 void print_marc(const char *marc_buf, int marc_buf_size)
2115 char *result; /* for result buf */
2116 size_t result_len; /* for size of result */
2117 yaz_marc_t mt = yaz_marc_create();
2118 yaz_marc_xml(mt, YAZ_MARC_LINE);
2119 yaz_marc_decode_buf(mt, marc_buf, marc_buf_size,
2120 &result, &result_len);
2121 fwrite(result, result_len, 1, stdout);
2122 yaz_marc_destroy(mt); /* note that result is now freed... */
2128 <sect2 id="tools.turbomarc">
2129 <title>TurboMARC</title>
2131 TurboMARC is yet another XML encoding of a MARC record. The format
2132 was designed for fast processing with XSLT.
2136 Pazpar2 uses XSLT to convert an XML encoded MARC record to an internal
2137 representation. This conversion mostly check the tag of a MARC field
2138 to determine the basic rules in the conversion. This check is
2139 costly when that is tag is encoded as an attribute in MARCXML.
2140 By having the tag value as the element instead, makes processing
2141 many times faster (at least for Libxslt).
2144 TurboMARC is encoded as follows:
2147 Record elements is part of namespace
2148 "<literal>http://www.indexdata.com/turbomarc</literal>".
2151 A record is enclosed in element <literal>r</literal>.
2154 A collection of records is enclosed in element
2155 <literal>collection</literal>.
2158 The leader is encoded as element <literal>l</literal> with the
2159 leader content as its (text) value.
2162 A control field is encoded as element <literal>c</literal> concatenated
2163 with the tag value of the control field if the tag value
2164 matches the regular expression <literal>[a-zA-Z0-9]*</literal>.
2165 If the tag value do not match the regular expression
2166 <literal>[a-zA-Z0-9]*</literal> the control field is encoded
2167 as element <literal>c</literal> and attribute <literal>code</literal>
2168 will hold the tag value.
2169 This rule ensure that in the rare cases where a tag value might
2170 result in a non-wellformed XML YAZ encode it as a coded attribute
2174 The control field content is the the text value of this element.
2175 Indicators are encoded as attribute names
2176 <literal>i1</literal>, <literal>i2</literal>, etc.. and
2177 corresponding values for each indicator.
2180 A data field is encoded as element <literal>d</literal> concatenated
2181 with the tag value of the data field or using the attribute
2182 <literal>code</literal> as described in the rules for control fields.
2183 The children of the data field element is subfield elements.
2184 Each subfield element is encoded as <literal>s</literal>
2185 concatenated with the sub field code.
2186 The text of the subfield element is the contents of the subfield.
2187 Indicators are encoded as attributes for the data field element similar
2188 to the encoding for control fields.
2195 <sect1 id="tools.retrieval">
2196 <title>Retrieval Facility</title>
2198 YAZ version 2.1.20 or later includes a Retrieval facility tool
2199 which allows a SRU/Z39.50 to describe itself and perform record
2200 conversions. The idea is the following:
2205 An SRU/Z39.50 client sends a retrieval request which includes
2206 a combination of the following parameters: syntax (format),
2207 schema (or element set name).
2213 The retrieval facility is invoked with parameters in a
2214 server/proxy. The retrieval facility matches the parameters a set of
2215 "supported" retrieval types.
2216 If there is no match, the retrieval signals an error
2217 (syntax and / or schema not supported).
2223 For a successful match, the backend is invoked with the same
2224 or altered retrieval parameters (syntax, schema). If
2225 a record is received from the backend, it is converted to the
2226 frontend name / syntax.
2232 The resulting record is sent back the client and tagged with
2233 the frontend syntax / schema.
2240 The Retrieval facility is driven by an XML configuration. The
2241 configuration is neither Z39.50 ZeeRex or SRU ZeeRex. But it
2242 should be easy to generate both of them from the XML configuration.
2243 (unfortunately the two versions
2244 of ZeeRex differ substantially in this regard).
2246 <sect2 id="tools.retrieval.format">
2247 <title>Retrieval XML format</title>
2249 All elements should be covered by namespace
2250 <literal>http://indexdata.com/yaz</literal> .
2251 The root element node must be <literal>retrievalinfo</literal>.
2254 The <literal>retrievalinfo</literal> must include one or
2255 more <literal>retrieval</literal> elements. Each
2256 <literal>retrieval</literal> defines specific combination of
2257 syntax, name and identifier supported by this retrieval service.
2260 The <literal>retrieval</literal> element may include any of the
2261 following attributes:
2263 <varlistentry><term><literal>syntax</literal> (REQUIRED)</term>
2266 Defines the record syntax. Possible values is any
2267 of the names defined in YAZ' OID database or a raw
2272 <varlistentry><term><literal>name</literal> (OPTIONAL)</term>
2275 Defines the name of the retrieval format. This can be
2276 any string. For SRU, the value, is equivalent to schema (short-hand);
2277 for Z39.50 it's equivalent to simple element set name.
2278 For YAZ 3.0.24 and later this name may be specified as a glob
2279 expression with operators
2280 <literal>*</literal> and <literal>?</literal>.
2284 <varlistentry><term><literal>identifier</literal> (OPTIONAL)</term>
2287 Defines the URI schema name of the retrieval format. This can be
2288 any string. For SRU, the value, is equivalent to URI schema.
2289 For Z39.50, there is no equivalent.
2296 The <literal>retrieval</literal> may include one
2297 <literal>backend</literal> element. If a <literal>backend</literal>
2298 element is given, it specifies how the records are retrieved by
2299 some backend and how the records are converted from the backend to
2303 The attributes, <literal>name</literal> and <literal>syntax</literal>
2304 may be specified for the <literal>backend</literal> element. These
2305 semantics of these attributes is equivalent to those for the
2306 <literal>retrieval</literal>. However, these values are passed to
2310 The <literal>backend</literal> element may includes one or more
2311 conversion instructions (as children elements). The supported
2314 <varlistentry><term><literal>marc</literal></term>
2317 The <literal>marc</literal> element specifies a conversion
2318 to - and from ISO2709 encoded MARC and
2319 <ulink url="&url.marcxml;">&acro.marcxml;</ulink>/MarcXchange.
2320 The following attributes may be specified:
2323 <varlistentry><term><literal>inputformat</literal> (REQUIRED)</term>
2326 Format of input. Supported values are
2327 <literal>marc</literal> (for ISO2709); and <literal>xml</literal>
2328 for MARCXML/MarcXchange.
2333 <varlistentry><term><literal>outputformat</literal> (REQUIRED)</term>
2336 Format of output. Supported values are
2337 <literal>line</literal> (MARC line format);
2338 <literal>marcxml</literal> (for MARCXML),
2339 <literal>marc</literal> (ISO2709),
2340 <literal>marcxhcange</literal> (for MarcXchange).
2345 <varlistentry><term><literal>inputcharset</literal> (OPTIONAL)</term>
2348 Encoding of input. For XML input formats, this need not
2349 be given, but for ISO2709 based inputformats, this should
2350 be set to the encoding used. For MARC21 records, a common
2351 inputcharset value would be <literal>marc-8</literal>.
2356 <varlistentry><term><literal>outputcharset</literal> (OPTIONAL)</term>
2359 Encoding of output. If outputformat is XML based, it is
2360 strongly recommened to use <literal>utf-8</literal>.
2369 <varlistentry><term><literal>xslt</literal></term>
2372 The <literal>xslt</literal> element specifies a conversion
2373 via &acro.xslt;. The following attributes may be specified:
2376 <varlistentry><term><literal>stylesheet</literal> (REQUIRED)</term>
2391 <sect2 id="tools.retrieval.examples">
2392 <title>Retrieval Facility Examples</title>
2393 <example id="tools.retrieval.marc21">
2394 <title>MARC21 backend</title>
2396 A typical way to use the retrieval facility is to enable XML
2397 for servers that only supports ISO2709 encoded MARC21 records.
2399 <programlisting><![CDATA[
2401 <retrieval syntax="usmarc" name="F"/>
2402 <retrieval syntax="usmarc" name="B"/>
2403 <retrieval syntax="xml" name="marcxml"
2404 identifier="info:srw/schema/1/marcxml-v1.1">
2405 <backend syntax="usmarc" name="F">
2406 <marc inputformat="marc" outputformat="marcxml"
2407 inputcharset="marc-8"/>
2410 <retrieval syntax="xml" name="dc">
2411 <backend syntax="usmarc" name="F">
2412 <marc inputformat="marc" outputformat="marcxml"
2413 inputcharset="marc-8"/>
2414 <xslt stylesheet="MARC21slim2DC.xsl"/>
2421 This means that our frontend supports:
2425 MARC21 F(ull) records.
2430 MARC21 B(rief) records.
2442 Dublin core records.
2449 <sect2 id="tools.retrieval.api">
2452 It should be easy to use the retrieval systems from applications. Refer
2454 <filename>yaz/retrieval.h</filename> and
2455 <filename>yaz/record_conv.h</filename>.
2461 <!-- Keep this comment at the end of the file
2466 sgml-minimize-attributes:nil
2467 sgml-always-quote-attributes:t
2470 sgml-parent-document: "yaz.xml"
2471 sgml-local-catalogs: nil
2472 sgml-namecase-general:t