1 <!-- $Id: tools.xml,v 1.54 2006-10-31 09:15:00 mike Exp $ -->
2 <chapter id="tools"><title>Supporting Tools</title>
5 In support of the service API - primarily the ASN module, which
6 provides the pro-grammatic interface to the Z39.50 APDUs, &yaz; contains
7 a collection of tools that support the development of applications.
10 <sect1 id="tools.query"><title>Query Syntax Parsers</title>
13 Since the type-1 (RPN) query structure has no direct, useful string
14 representation, every origin application needs to provide some form of
15 mapping from a local query notation or representation to a
16 <token>Z_RPNQuery</token> structure. Some programmers will prefer to
17 construct the query manually, perhaps using
18 <function>odr_malloc()</function> to simplify memory management.
19 The &yaz; distribution includes three separate, query-generating tools
20 that may be of use to you.
23 <sect2 id="PQF"><title>Prefix Query Format</title>
26 Since RPN or reverse polish notation is really just a fancy way of
27 describing a suffix notation format (operator follows operands), it
28 would seem that the confusion is total when we now introduce a prefix
29 notation for RPN. The reason is one of simple laziness - it's somewhat
30 simpler to interpret a prefix format, and this utility was designed
31 for maximum simplicity, to provide a baseline representation for use
32 in simple test applications and scripting environments (like Tcl). The
33 demonstration client included with YAZ uses the PQF.
38 The PQF have been adopted by other parties developing Z39.50
39 software. It is often referred to as Prefix Query Notation
44 The PQF is defined by the pquery module in the YAZ library.
45 There are two sets of function that have similar behavior. First
46 set operates on a PQF parser handle, second set doesn't. First set
47 set of functions are more flexible than the second set. Second set
48 is obsolete and is only provided to ensure backwards compatibility.
51 First set of functions all operate on a PQF parser handle:
54 #include <yaz/pquery.h>
56 YAZ_PQF_Parser yaz_pqf_create (void);
58 void yaz_pqf_destroy (YAZ_PQF_Parser p);
60 Z_RPNQuery *yaz_pqf_parse (YAZ_PQF_Parser p, ODR o, const char *qbuf);
62 Z_AttributesPlusTerm *yaz_pqf_scan (YAZ_PQF_Parser p, ODR o,
63 Odr_oid **attributeSetId, const char *qbuf);
66 int yaz_pqf_error (YAZ_PQF_Parser p, const char **msg, size_t *off);
69 A PQF parser is created and destructed by functions
70 <function>yaz_pqf_create</function> and
71 <function>yaz_pqf_destroy</function> respectively.
72 Function <function>yaz_pqf_parse</function> parses query given
73 by string <literal>qbuf</literal>. If parsing was successful,
74 a Z39.50 RPN Query is returned which is created using ODR stream
75 <literal>o</literal>. If parsing failed, a NULL pointer is
77 Function <function>yaz_pqf_scan</function> takes a scan query in
78 <literal>qbuf</literal>. If parsing was successful, the function
79 returns attributes plus term pointer and modifies
80 <literal>attributeSetId</literal> to hold attribute set for the
81 scan request - both allocated using ODR stream <literal>o</literal>.
82 If parsing failed, yaz_pqf_scan returns a NULL pointer.
83 Error information for bad queries can be obtained by a call to
84 <function>yaz_pqf_error</function> which returns an error code and
85 modifies <literal>*msg</literal> to point to an error description,
86 and modifies <literal>*off</literal> to the offset within last
87 query were parsing failed.
90 The second set of functions are declared as follows:
93 #include <yaz/pquery.h>
95 Z_RPNQuery *p_query_rpn (ODR o, oid_proto proto, const char *qbuf);
97 Z_AttributesPlusTerm *p_query_scan (ODR o, oid_proto proto,
98 Odr_oid **attributeSetP, const char *qbuf);
100 int p_query_attset (const char *arg);
103 The function <function>p_query_rpn()</function> takes as arguments an
104 &odr; stream (see section <link linkend="odr">The ODR Module</link>)
105 to provide a memory source (the structure created is released on
106 the next call to <function>odr_reset()</function> on the stream), a
107 protocol identifier (one of the constants <token>PROTO_Z3950</token> and
108 <token>PROTO_SR</token>), an attribute set reference, and
109 finally a null-terminated string holding the query string.
112 If the parse went well, <function>p_query_rpn()</function> returns a
113 pointer to a <literal>Z_RPNQuery</literal> structure which can be
114 placed directly into a <literal>Z_SearchRequest</literal>.
115 If parsing failed, due to syntax error, a NULL pointer is returned.
118 The <literal>p_query_attset</literal> specifies which attribute set
119 to use if the query doesn't specify one by the
120 <literal>@attrset</literal> operator.
121 The <literal>p_query_attset</literal> returns 0 if the argument is a
122 valid attribute set specifier; otherwise the function returns -1.
126 The grammar of the PQF is as follows:
130 query ::= top-set query-struct.
132 top-set ::= [ '@attrset' string ]
134 query-struct ::= attr-spec | simple | complex | '@term' term-type query
136 attr-spec ::= '@attr' [ string ] string query-struct
138 complex ::= operator query-struct query-struct.
140 operator ::= '@and' | '@or' | '@not' | '@prox' proximity.
142 simple ::= result-set | term.
144 result-set ::= '@set' string.
148 proximity ::= exclusion distance ordered relation which-code unit-code.
150 exclusion ::= '1' | '0' | 'void'.
152 distance ::= integer.
154 ordered ::= '1' | '0'.
156 relation ::= integer.
158 which-code ::= 'known' | 'private' | integer.
160 unit-code ::= integer.
162 term-type ::= 'general' | 'numeric' | 'string' | 'oid' | 'datetime' | 'null'.
166 You will note that the syntax above is a fairly faithful
167 representation of RPN, except for the Attribute, which has been
168 moved a step away from the term, allowing you to associate one or more
169 attributes with an entire query structure. The parser will
170 automatically apply the given attributes to each term as required.
174 The @attr operator is followed by an attribute specification
175 (<literal>attr-spec</literal> above). The specification consists
176 of an optional attribute set, an attribute type-value pair and
177 a sub-query. The attribute type-value pair is packed in one string:
178 an attribute type, an equals sign, and an attribute value, like this:
179 <literal>@attr 1=1003</literal>.
180 The type is always an integer but the value may be either an
181 integer or a string (if it doesn't start with a digit character).
182 A string attribute-value is encoded as a Type-1 ``complex''
183 attribute with the list of values containing the single string
184 specified, and including no semantic indicators.
188 Version 3 of the Z39.50 specification defines various encoding of terms.
189 Use <literal>@term </literal> <replaceable>type</replaceable>
190 <replaceable>string</replaceable>,
191 where type is one of: <literal>general</literal>,
192 <literal>numeric</literal> or <literal>string</literal>
193 (for InternationalString).
194 If no term type has been given, the <literal>general</literal> form
195 is used. This is the only encoding allowed in both versions 2 and 3
196 of the Z39.50 standard.
199 <sect3 id="PQF-prox">
200 <title>Using Proximity Operators with PQF</title>
203 This is an advanced topic, describing how to construct
204 queries that make very specific requirements on the
205 relative location of their operands.
206 You may wish to skip this section and go straight to
207 <link linkend="pqf-examples">the example PQF queries</link>.
212 Most Z39.50 servers do not support proximity searching, or
213 support only a small subset of the full functionality that
214 can be expressed using the PQF proximity operator. Be
215 aware that the ability to <emphasis>express</emphasis> a
216 query in PQF is no guarantee that any given server will
217 be able to <emphasis>execute</emphasis> it.
223 The proximity operator <literal>@prox</literal> is a special
224 and more restrictive version of the conjunction operator
225 <literal>@and</literal>. Its semantics are described in
226 section 3.7.2 (Proximity) of Z39.50 the standard itself, which
227 can be read on-line at
228 <ulink url="&url.z39.50.proximity;"/>
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="&url.z39.50.proximity.asn1;"
298 >the ASN.1</ulink> of the proximity structure in the standard.)
302 <sect3 id="pqf-examples"><title>PQF queries</title>
304 <example id="example.pqf.simple.terms">
305 <title>PQF queries using simple terms</title>
314 <example id="pqf.example.pqf.boolean.operators">
315 <title>PQF boolean operators</title>
318 @or "dylan" "zimmerman"
320 @and @or dylan zimmerman when
322 @and when @or dylan zimmerman
326 <example id="example.pqf.result.sets">
327 <title>PQF references to result sets</title>
332 @and @set seta @set setb
336 <example id="example.pqf.attributes">
337 <title>Attributes for terms</title>
342 @attr 1=4 @attr 4=1 "self portrait"
344 @attrset exp1 @attr 1=1 CategoryList
346 @attr gils 1=2008 Copenhagen
348 @attr 1=/book/title computer
352 <example id="example.pqf.proximity">
353 <title>PQF Proximity queries</title>
356 @prox 0 3 1 2 k 2 dylan zimmerman
359 Here the parameters 0, 3, 1, 2, k and 2 represent exclusion,
360 distance, ordered, relation, which-code and unit-code, in that
364 exclusion = 0: the proximity condition must hold
367 distance = 3: the terms must be three units apart
370 ordered = 1: they must occur in the order they are specified
373 relation = 2: lessThanOrEqual (to the distance of 3 units)
376 which-code is ``known'', so the standard unit-codes are used
382 So the whole proximity query means that the words
383 <literal>dylan</literal> and <literal>zimmerman</literal> must
384 both occur in the record, in that order, differing in position
385 by three or fewer words (i.e. with two or fewer words between
386 them.) The query would find ``Bob Dylan, aka. Robert
387 Zimmerman'', but not ``Bob Dylan, born as Robert Zimmerman''
388 since the distance in this case is four.
392 <example id="example.pqf.search.term.type">
393 <title>PQF specification of search term type</title>
396 @term string "a UTF-8 string, maybe?"
400 <example id="example.pqf.mixed.queries">
401 <title>PQF mixed queries</title>
404 @or @and bob dylan @set Result-1
406 @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming"
408 @and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109
412 The last of these examples is a spatial search: in
413 <ulink url="http://www.gils.net/prof_v2.html#sec_7_4"
414 >the GILS attribute set</ulink>,
416 2038 indicates West Bounding Coordinate and
417 2030 indicates East Bounding Coordinate,
418 so the query is for areas extending from -114 degrees
419 to no more than -109 degrees.
426 <sect2 id="CCL"><title>CCL</title>
429 Not all users enjoy typing in prefix query structures and numerical
430 attribute values, even in a minimalistic test client. In the library
431 world, the more intuitive Common Command Language - CCL (ISO 8777)
432 has enjoyed some popularity - especially before the widespread
433 availability of graphical interfaces. It is still useful in
434 applications where you for some reason or other need to provide a
435 symbolic language for expressing boolean query structures.
439 The EUROPAGATE research project working under the Libraries programme
440 of the European Commission's DG XIII has, amongst other useful tools,
441 implemented a general-purpose CCL parser which produces an output
442 structure that can be trivially converted to the internal RPN
443 representation of &yaz; (The <literal>Z_RPNQuery</literal> structure).
444 Since the CCL utility - along with the rest of the software
445 produced by EUROPAGATE - is made freely available on a liberal
446 license, it is included as a supplement to &yaz;.
449 <sect3 id="ccl.syntax">
450 <title>CCL Syntax</title>
453 The CCL parser obeys the following grammar for the FIND argument.
454 The syntax is annotated by in the lines prefixed by
455 <literal>‐‐</literal>.
459 CCL-Find ::= CCL-Find Op Elements
462 Op ::= "and" | "or" | "not"
463 -- The above means that Elements are separated by boolean operators.
465 Elements ::= '(' CCL-Find ')'
468 | Qualifiers Relation Terms
469 | Qualifiers Relation '(' CCL-Find ')'
470 | Qualifiers '=' string '-' string
471 -- Elements is either a recursive definition, a result set reference, a
472 -- list of terms, qualifiers followed by terms, qualifiers followed
473 -- by a recursive definition or qualifiers in a range (lower - upper).
475 Set ::= 'set' = string
476 -- Reference to a result set
478 Terms ::= Terms Prox Term
480 -- Proximity of terms.
484 -- This basically means that a term may include a blank
486 Qualifiers ::= Qualifiers ',' string
488 -- Qualifiers is a list of strings separated by comma
490 Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<'
491 -- Relational operators. This really doesn't follow the ISO8777
495 -- Proximity operator
499 <example id="example.ccl.queries">
500 <title>CCL queries</title>
502 The following queries are all valid:
514 (dylan and bob) or set=1
518 Assuming that the qualifiers <literal>ti</literal>,
519 <literal>au</literal>
520 and <literal>date</literal> are defined we may use:
526 au=(bob dylan and slow train coming)
528 date>1980 and (ti=((self portrait)))
534 <sect3 id="ccl.qualifiers">
535 <title>CCL Qualifiers</title>
538 Qualifiers are used to direct the search to a particular searchable
539 index, such as title (ti) and author indexes (au). The CCL standard
540 itself doesn't specify a particular set of qualifiers, but it does
541 suggest a few short-hand notations. You can customize the CCL parser
542 to support a particular set of qualifiers to reflect the current target
543 profile. Traditionally, a qualifier would map to a particular
544 use-attribute within the BIB-1 attribute set. It is also
545 possible to set other attributes, such as the structure
550 A CCL profile is a set of predefined CCL qualifiers that may be
551 read from a file or set in the CCL API.
552 The YAZ client reads its CCL qualifiers from a file named
553 <filename>default.bib</filename>. There are four types of
554 lines in a CCL profile: qualifier specification,
555 qualifier alias, comments and directives.
557 <sect4 id="ccl.qualifier.specification">
558 <title>Qualifier specification</title>
560 A qualifier specification is of the form:
564 <replaceable>qualifier-name</replaceable>
565 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable>
566 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable> ...
570 where <replaceable>qualifier-name</replaceable> is the name of the
571 qualifier to be used (eg. <literal>ti</literal>),
572 <replaceable>type</replaceable> is attribute type in the attribute
573 set (Bib-1 is used if no attribute set is given) and
574 <replaceable>val</replaceable> is attribute value.
575 The <replaceable>type</replaceable> can be specified as an
576 integer or as it be specified either as a single-letter:
577 <literal>u</literal> for use,
578 <literal>r</literal> for relation,<literal>p</literal> for position,
579 <literal>s</literal> for structure,<literal>t</literal> for truncation
580 or <literal>c</literal> for completeness.
581 The attributes for the special qualifier name <literal>term</literal>
582 are used when no CCL qualifier is given in a query.
583 <table id="ccl.common.bib1.attributes">
584 <title>Common Bib-1 attributes</title>
586 <colspec colwidth="2*" colname="type"></colspec>
587 <colspec colwidth="9*" colname="description"></colspec>
591 <entry>Description</entry>
596 <entry><literal>u=</literal><replaceable>value</replaceable></entry>
598 Use attribute (1). Common use attributes are
599 1 Personal-name, 4 Title, 7 ISBN, 8 ISSN, 30 Date,
600 62 Subject, 1003 Author), 1016 Any. Specify value
606 <entry><literal>r=</literal><replaceable>value</replaceable></entry>
608 Relation attribute (2). Common values are
609 1 <, 2 <=, 3 =, 4 >=, 5 >, 6 <>,
610 100 phonetic, 101 stem, 102 relevance, 103 always matches.
615 <entry><literal>p=</literal><replaceable>value</replaceable></entry>
617 Position attribute (3). Values: 1 first in field, 2
618 first in any subfield, 3 any position in field.
623 <entry><literal>s=</literal><replaceable>value</replaceable></entry>
625 Structure attribute (4). Values: 1 phrase, 2 word,
626 3 key, 4 year, 5 date, 6 word list, 100 date (un),
627 101 name (norm), 102 name (un), 103 structure, 104 urx,
628 105 free-form-text, 106 document-text, 107 local-number,
629 108 string, 109 numeric string.
634 <entry><literal>t=</literal><replaceable>value</replaceable></entry>
636 Truncation attribute (5). Values: 1 right, 2 left,
637 3 left& right, 100 none, 101 process #, 102 regular-1,
638 103 regular-2, 104 CCL.
643 <entry><literal>c=</literal><replaceable>value</replaceable></entry>
645 Completeness attribute (6). Values: 1 incomplete subfield,
646 2 complete subfield, 3 complete field.
655 Refer to the complete
656 <ulink url="&url.z39.50.attset.bib1;">list of Bib-1 attributes</ulink>
659 It is also possible to specify non-numeric attribute values,
660 which are used in combination with certain types.
661 The special combinations are:
663 <table id="ccl.special.attribute.combos">
664 <title>Special attribute combos</title>
666 <colspec colwidth="2*" colname="name"></colspec>
667 <colspec colwidth="9*" colname="description"></colspec>
671 <entry>Description</entry>
676 <entry><literal>s=pw</literal></entry><entry>
677 The structure is set to either word or phrase depending
678 on the number of tokens in a term (phrase-word).
682 <entry><literal>s=al</literal></entry><entry>
683 Each token in the term is ANDed. (and-list).
684 This does not set the structure at all.
688 <row><entry><literal>s=ol</literal></entry><entry>
689 Each token in the term is ORed. (or-list).
690 This does not set the structure at all.
694 <row><entry><literal>r=o</literal></entry><entry>
695 Allows ranges and the operators greather-than, less-than, ...
697 This sets Bib-1 relation attribute accordingly (relation
698 ordered). A query construct is only treated as a range if
699 dash is used and that is surrounded by white-space. So
700 <literal>-1980</literal> is treated as term
701 <literal>"-1980"</literal> not <literal><= 1980</literal>.
702 If <literal>- 1980</literal> is used, however, that is
707 <row><entry><literal>r=r</literal></entry><entry>
708 Similar to <literal>r=o</literal> but assumes that terms
709 are non-negative (not prefixed with <literal>-</literal>).
710 Thus, a dash will always be treated as a range.
711 The construct <literal>1980-1990</literal> is
712 treated as a range with <literal>r=r</literal> but as a
713 single term <literal>"1980-1990"</literal> with
714 <literal>r=o</literal>. The special attribute
715 <literal>r=r</literal> is available in YAZ 2.0.24 or later.
719 <row><entry><literal>t=l</literal></entry><entry>
720 Allows term to be left-truncated.
721 If term is of the form <literal>?x</literal>, the resulting
722 Type-1 term is <literal>x</literal> and truncation is left.
726 <row><entry><literal>t=r</literal></entry><entry>
727 Allows term to be right-truncated.
728 If term is of the form <literal>x?</literal>, the resulting
729 Type-1 term is <literal>x</literal> and truncation is right.
733 <row><entry><literal>t=n</literal></entry><entry>
734 If term is does not include <literal>?</literal>, the
735 truncation attribute is set to none (100).
739 <row><entry><literal>t=b</literal></entry><entry>
740 Allows term to be both left&right truncated.
741 If term is of the form <literal>?x?</literal>, the
742 resulting term is <literal>x</literal> and trunctation is
743 set to both left&right.
750 <example id="example.ccl.profile"><title>CCL profile</title>
752 Consider the following definition:
763 <literal>ti</literal> and <literal>au</literal> both set
764 structure attribute to phrase (s=1).
765 <literal>ti</literal>
766 sets the use-attribute to 4. <literal>au</literal> sets the
768 When no qualifiers are used in the query the structure-attribute is
769 set to free-form-text (105) (rule for <literal>term</literal>).
770 The <literal>date</literal> sets the relation attribute to
771 the relation used in the CCL query and sets the use attribute
775 You can combine attributes. To Search for "ranked title" you
778 ti,ranked=knuth computer
780 which will set relation=ranked, use=title, structure=phrase.
787 is a valid query. But
795 <sect4 id="ccl.qualifier.alias">
796 <title>Qualifier alias</title>
798 A qualifier alias is of the form:
801 <replaceable>q</replaceable>
802 <replaceable>q1</replaceable> <replaceable>q2</replaceable> ..
805 which declares <replaceable>q</replaceable> to
806 be an alias for <replaceable>q1</replaceable>,
807 <replaceable>q2</replaceable>... such that the CCL
808 query <replaceable>q=x</replaceable> is equivalent to
809 <replaceable>q1=x or q2=x or ...</replaceable>.
813 <sect4 id="ccl.comments">
814 <title>Comments</title>
816 Lines with white space or lines that begin with
817 character <literal>#</literal> are treated as comments.
821 <sect4 id="ccl.directives">
822 <title>Directives</title>
824 Directive specifications takes the form
826 <para><literal>@</literal><replaceable>directive</replaceable> <replaceable>value</replaceable>
828 <table id="ccl.directives.table">
829 <title>CCL directives</title>
831 <colspec colwidth="2*" colname="name"></colspec>
832 <colspec colwidth="8*" colname="description"></colspec>
833 <colspec colwidth="1*" colname="default"></colspec>
837 <entry>Description</entry>
838 <entry>Default</entry>
843 <entry>truncation</entry>
844 <entry>Truncation character</entry>
845 <entry><literal>?</literal></entry>
849 <entry>Specifies how multiple fields are to be
850 combined. There are two modes: <literal>or</literal>:
851 multiple qualifier fields are ORed,
852 <literal>merge</literal>: attributes for the qualifier
853 fields are merged and assigned to one term.
855 <entry><literal>merge</literal></entry>
859 <entry>Specificies if CCL operatores and qualifiers should be
860 compared with case sensitivity or not. Specify 0 for
861 case sensitive; 1 for case insensitive.</entry>
862 <entry><literal>0</literal></entry>
867 <entry>Specifies token for CCL operator AND.</entry>
868 <entry><literal>and</literal></entry>
873 <entry>Specifies token for CCL operator OR.</entry>
874 <entry><literal>or</literal></entry>
879 <entry>Specifies token for CCL operator NOT.</entry>
880 <entry><literal>not</literal></entry>
885 <entry>Specifies token for CCL operator SET.</entry>
886 <entry><literal>set</literal></entry>
894 <title>CCL API</title>
896 All public definitions can be found in the header file
897 <filename>ccl.h</filename>. A profile identifier is of type
898 <literal>CCL_bibset</literal>. A profile must be created with the call
899 to the function <function>ccl_qual_mk</function> which returns a profile
900 handle of type <literal>CCL_bibset</literal>.
904 To read a file containing qualifier definitions the function
905 <function>ccl_qual_file</function> may be convenient. This function
906 takes an already opened <literal>FILE</literal> handle pointer as
907 argument along with a <literal>CCL_bibset</literal> handle.
911 To parse a simple string with a FIND query use the function
914 struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str,
915 int *error, int *pos);
918 which takes the CCL profile (<literal>bibset</literal>) and query
919 (<literal>str</literal>) as input. Upon successful completion the RPN
920 tree is returned. If an error occur, such as a syntax error, the integer
921 pointed to by <literal>error</literal> holds the error code and
922 <literal>pos</literal> holds the offset inside query string in which
927 An English representation of the error may be obtained by calling
928 the <literal>ccl_err_msg</literal> function. The error codes are
929 listed in <filename>ccl.h</filename>.
933 To convert the CCL RPN tree (type
934 <literal>struct ccl_rpn_node *</literal>)
935 to the Z_RPNQuery of YAZ the function <function>ccl_rpn_query</function>
936 must be used. This function which is part of YAZ is implemented in
937 <filename>yaz-ccl.c</filename>.
938 After calling this function the CCL RPN tree is probably no longer
939 needed. The <literal>ccl_rpn_delete</literal> destroys the CCL RPN tree.
943 A CCL profile may be destroyed by calling the
944 <function>ccl_qual_rm</function> function.
948 The token names for the CCL operators may be changed by setting the
949 globals (all type <literal>char *</literal>)
950 <literal>ccl_token_and</literal>, <literal>ccl_token_or</literal>,
951 <literal>ccl_token_not</literal> and <literal>ccl_token_set</literal>.
952 An operator may have aliases, i.e. there may be more than one name for
953 the operator. To do this, separate each alias with a space character.
957 <sect2 id="cql"><title>CQL</title>
959 <ulink url="&url.cql;">CQL</ulink>
960 - Common Query Language - was defined for the
961 <ulink url="&url.sru;">SRU</ulink> protocol.
962 In many ways CQL has a similar syntax to CCL.
963 The objective of CQL is different. Where CCL aims to be
964 an end-user language, CQL is <emphasis>the</emphasis> protocol
965 query language for SRU.
969 If you are new to CQL, read the
970 <ulink url="&url.cql.intro;">Gentle Introduction</ulink>.
974 The CQL parser in &yaz; provides the following:
978 It parses and validates a CQL query.
983 It generates a C structure that allows you to convert
984 a CQL query to some other query language, such as SQL.
989 The parser converts a valid CQL query to PQF, thus providing a
990 way to use CQL for both SRU servers and Z39.50 targets at the
996 The parser converts CQL to
997 <ulink url="&url.xcql;">XCQL</ulink>.
998 XCQL is an XML representation of CQL.
999 XCQL is part of the SRU specification. However, since SRU
1000 supports CQL only, we don't expect XCQL to be widely used.
1001 Furthermore, CQL has the advantage over XCQL that it is
1007 <sect3 id="cql.parsing"><title>CQL parsing</title>
1009 A CQL parser is represented by the <literal>CQL_parser</literal>
1010 handle. Its contents should be considered &yaz; internal (private).
1012 #include <yaz/cql.h>
1014 typedef struct cql_parser *CQL_parser;
1016 CQL_parser cql_parser_create(void);
1017 void cql_parser_destroy(CQL_parser cp);
1019 A parser is created by <function>cql_parser_create</function> and
1020 is destroyed by <function>cql_parser_destroy</function>.
1023 To parse a CQL query string, the following function
1026 int cql_parser_string(CQL_parser cp, const char *str);
1028 A CQL query is parsed by the <function>cql_parser_string</function>
1029 which takes a query <parameter>str</parameter>.
1030 If the query was valid (no syntax errors), then zero is returned;
1031 otherwise -1 is returned to indicate a syntax error.
1035 int cql_parser_stream(CQL_parser cp,
1036 int (*getbyte)(void *client_data),
1037 void (*ungetbyte)(int b, void *client_data),
1040 int cql_parser_stdio(CQL_parser cp, FILE *f);
1042 The functions <function>cql_parser_stream</function> and
1043 <function>cql_parser_stdio</function> parses a CQL query
1044 - just like <function>cql_parser_string</function>.
1045 The only difference is that the CQL query can be
1046 fed to the parser in different ways.
1047 The <function>cql_parser_stream</function> uses a generic
1048 byte stream as input. The <function>cql_parser_stdio</function>
1049 uses a <literal>FILE</literal> handle which is opened for reading.
1053 <sect3 id="cql.tree"><title>CQL tree</title>
1055 The the query string is valid, the CQL parser
1056 generates a tree representing the structure of the
1061 struct cql_node *cql_parser_result(CQL_parser cp);
1063 <function>cql_parser_result</function> returns the
1064 a pointer to the root node of the resulting tree.
1067 Each node in a CQL tree is represented by a
1068 <literal>struct cql_node</literal>.
1069 It is defined as follows:
1071 #define CQL_NODE_ST 1
1072 #define CQL_NODE_BOOL 2
1082 struct cql_node *modifiers;
1086 struct cql_node *left;
1087 struct cql_node *right;
1088 struct cql_node *modifiers;
1093 There are two node types: search term (ST) and boolean (BOOL).
1094 A modifier is treated as a search term too.
1097 The search term node has five members:
1101 <literal>index</literal>: index for search term.
1102 If an index is unspecified for a search term,
1103 <literal>index</literal> will be NULL.
1108 <literal>index_uri</literal>: index URi for search term
1109 or NULL if none could be resolved for the index.
1114 <literal>term</literal>: the search term itself.
1119 <literal>relation</literal>: relation for search term.
1124 <literal>relation_uri</literal>: relation URI for search term.
1129 <literal>modifiers</literal>: relation modifiers for search
1130 term. The <literal>modifiers</literal> list itself of cql_nodes
1131 each of type <literal>ST</literal>.
1138 The boolean node represents both <literal>and</literal>,
1139 <literal>or</literal>, not as well as
1144 <literal>left</literal> and <literal>right</literal>: left
1145 - and right operand respectively.
1150 <literal>modifiers</literal>: proximity arguments.
1157 <sect3 id="cql.to.pqf"><title>CQL to PQF conversion</title>
1159 Conversion to PQF (and Z39.50 RPN) is tricky by the fact
1160 that the resulting RPN depends on the Z39.50 target
1161 capabilities (combinations of supported attributes).
1162 In addition, the CQL and SRU operates on index prefixes
1163 (URI or strings), whereas the RPN uses Object Identifiers
1167 The CQL library of &yaz; defines a <literal>cql_transform_t</literal>
1168 type. It represents a particular mapping between CQL and RPN.
1169 This handle is created and destroyed by the functions:
1171 cql_transform_t cql_transform_open_FILE (FILE *f);
1172 cql_transform_t cql_transform_open_fname(const char *fname);
1173 void cql_transform_close(cql_transform_t ct);
1175 The first two functions create a tranformation handle from
1176 either an already open FILE or from a filename respectively.
1179 The handle is destroyed by <function>cql_transform_close</function>
1180 in which case no further reference of the handle is allowed.
1183 When a <literal>cql_transform_t</literal> handle has been created
1184 you can convert to RPN.
1186 int cql_transform_buf(cql_transform_t ct,
1187 struct cql_node *cn, char *out, int max);
1189 This function converts the CQL tree <literal>cn</literal>
1190 using handle <literal>ct</literal>.
1191 For the resulting PQF, you supply a buffer <literal>out</literal>
1192 which must be able to hold at at least <literal>max</literal>
1196 If conversion failed, <function>cql_transform_buf</function>
1197 returns a non-zero SRU error code; otherwise zero is returned
1198 (conversion successful). The meanings of the numeric error
1199 codes are listed in the SRU specifications at
1200 <ulink url="&url.sru.diagnostics.list;"/>
1203 If conversion fails, more information can be obtained by calling
1205 int cql_transform_error(cql_transform_t ct, char **addinfop);
1207 This function returns the most recently returned numeric
1208 error-code and sets the string-pointer at
1209 <literal>*addinfop</literal> to point to a string containing
1210 additional information about the error that occurred: for
1211 example, if the error code is 15 (``Illegal or unsupported context
1212 set''), the additional information is the name of the requested
1213 context set that was not recognised.
1216 The SRU error-codes may be translated into brief human-readable
1217 error messages using
1219 const char *cql_strerror(int code);
1223 If you wish to be able to produce a PQF result in a different
1224 way, there are two alternatives.
1226 void cql_transform_pr(cql_transform_t ct,
1227 struct cql_node *cn,
1228 void (*pr)(const char *buf, void *client_data),
1231 int cql_transform_FILE(cql_transform_t ct,
1232 struct cql_node *cn, FILE *f);
1234 The former function produces output to a user-defined
1235 output stream. The latter writes the result to an already
1236 open <literal>FILE</literal>.
1239 <sect3 id="cql.to.rpn">
1240 <title>Specification of CQL to RPN mappings</title>
1242 The file supplied to functions
1243 <function>cql_transform_open_FILE</function>,
1244 <function>cql_transform_open_fname</function> follows
1245 a structure found in many Unix utilities.
1246 It consists of mapping specifications - one per line.
1247 Lines starting with <literal>#</literal> are ignored (comments).
1250 Each line is of the form
1252 <replaceable>CQL pattern</replaceable><literal> = </literal> <replaceable> RPN equivalent</replaceable>
1256 An RPN pattern is a simple attribute list. Each attribute pair
1259 [<replaceable>set</replaceable>] <replaceable>type</replaceable><literal>=</literal><replaceable>value</replaceable>
1261 The attribute <replaceable>set</replaceable> is optional.
1262 The <replaceable>type</replaceable> is the attribute type,
1263 <replaceable>value</replaceable> the attribute value.
1266 The following CQL patterns are recognized:
1268 <varlistentry><term>
1269 <literal>index.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1273 This pattern is invoked when a CQL index, such as
1274 dc.title is converted. <replaceable>set</replaceable>
1275 and <replaceable>name</replaceable> are the context set and index
1277 Typically, the RPN specifies an equivalent use attribute.
1280 For terms not bound by an index the pattern
1281 <literal>index.cql.serverChoice</literal> is used.
1282 Here, the prefix <literal>cql</literal> is defined as
1283 <literal>http://www.loc.gov/zing/cql/cql-indexes/v1.0/</literal>.
1284 If this pattern is not defined, the mapping will fail.
1288 <varlistentry><term>
1289 <literal>qualifier.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1294 For backwards compatibility, this is recognised as a synonym of
1295 <literal>index.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1299 <varlistentry><term>
1300 <literal>relation.</literal><replaceable>relation</replaceable>
1304 This pattern specifies how a CQL relation is mapped to RPN.
1305 <replaceable>pattern</replaceable> is name of relation
1306 operator. Since <literal>=</literal> is used as
1307 separator between CQL pattern and RPN, CQL relations
1308 including <literal>=</literal> cannot be
1309 used directly. To avoid a conflict, the names
1310 <literal>ge</literal>,
1311 <literal>eq</literal>,
1312 <literal>le</literal>,
1313 must be used for CQL operators, greater-than-or-equal,
1314 equal, less-than-or-equal respectively.
1315 The RPN pattern is supposed to include a relation attribute.
1318 For terms not bound by a relation, the pattern
1319 <literal>relation.scr</literal> is used. If the pattern
1320 is not defined, the mapping will fail.
1323 The special pattern, <literal>relation.*</literal> is used
1324 when no other relation pattern is matched.
1329 <varlistentry><term>
1330 <literal>relationModifier.</literal><replaceable>mod</replaceable>
1334 This pattern specifies how a CQL relation modifier is mapped to RPN.
1335 The RPN pattern is usually a relation attribute.
1340 <varlistentry><term>
1341 <literal>structure.</literal><replaceable>type</replaceable>
1345 This pattern specifies how a CQL structure is mapped to RPN.
1346 Note that this CQL pattern is somewhat to similar to
1347 CQL pattern <literal>relation</literal>.
1348 The <replaceable>type</replaceable> is a CQL relation.
1351 The pattern, <literal>structure.*</literal> is used
1352 when no other structure pattern is matched.
1353 Usually, the RPN equivalent specifies a structure attribute.
1358 <varlistentry><term>
1359 <literal>position.</literal><replaceable>type</replaceable>
1363 This pattern specifies how the anchor (position) of
1364 CQL is mapped to RPN.
1365 The <replaceable>type</replaceable> is one
1366 of <literal>first</literal>, <literal>any</literal>,
1367 <literal>last</literal>, <literal>firstAndLast</literal>.
1370 The pattern, <literal>position.*</literal> is used
1371 when no other position pattern is matched.
1376 <varlistentry><term>
1377 <literal>set.</literal><replaceable>prefix</replaceable>
1381 This specification defines a CQL context set for a given prefix.
1382 The value on the right hand side is the URI for the set -
1383 <emphasis>not</emphasis> RPN. All prefixes used in
1384 index patterns must be defined this way.
1390 <example id="example.cql.to.rpn.mapping"><title>CQL to RPN mapping file</title>
1392 This simple file defines two context sets, three indexes and three
1393 relations, a position pattern and a default structure.
1395 <programlisting><![CDATA[
1396 set.cql = http://www.loc.gov/zing/cql/context-sets/cql/v1.1/
1397 set.dc = http://www.loc.gov/zing/cql/dc-indexes/v1.0/
1399 index.cql.serverChoice = 1=1016
1400 index.dc.title = 1=4
1401 index.dc.subject = 1=21
1407 position.any = 3=3 6=1
1413 With the mappings above, the CQL query
1417 is converted to the PQF:
1419 @attr 1=1016 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "computer"
1421 by rules <literal>index.cql.serverChoice</literal>,
1422 <literal>relation.scr</literal>, <literal>structure.*</literal>,
1423 <literal>position.any</literal>.
1430 is rejected, since <literal>position.right</literal> is
1436 >my = "http://www.loc.gov/zing/cql/dc-indexes/v1.0/" my.title = x
1440 @attr 1=4 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "x"
1444 <example id="example.cql.to.rpn.bathprofile">
1445 <title>CQL to RPN using Bath Profile</title>
1447 The file <filename>etc/pqf.properties</filename> has mappings from
1448 the Bath Profile and Dublin Core to RPN.
1449 If YAZ is installed as a package it's usually located
1450 in <filename>/usr/share/yaz/etc</filename> and part of the
1451 development package, such as <literal>libyaz-dev</literal>.
1455 <sect3 id="cql.xcql"><title>CQL to XCQL conversion</title>
1457 Conversion from CQL to XCQL is trivial and does not
1458 require a mapping to be defined.
1459 There three functions to choose from depending on the
1460 way you wish to store the resulting output (XML buffer
1463 int cql_to_xml_buf(struct cql_node *cn, char *out, int max);
1464 void cql_to_xml(struct cql_node *cn,
1465 void (*pr)(const char *buf, void *client_data),
1467 void cql_to_xml_stdio(struct cql_node *cn, FILE *f);
1469 Function <function>cql_to_xml_buf</function> converts
1470 to XCQL and stores result in a user supplied buffer of a given
1474 <function>cql_to_xml</function> writes the result in
1475 a user defined output stream.
1476 <function>cql_to_xml_stdio</function> writes to a
1482 <sect1 id="tools.oid"><title>Object Identifiers</title>
1485 The basic YAZ representation of an OID is an array of integers,
1486 terminated with the value -1. The &odr; module provides two
1487 utility-functions to create and copy this type of data elements:
1491 Odr_oid *odr_getoidbystr(ODR o, char *str);
1495 Creates an OID based on a string-based representation using dots (.)
1496 to separate elements in the OID.
1500 Odr_oid *odr_oiddup(ODR odr, Odr_oid *o);
1504 Creates a copy of the OID referenced by the <emphasis>o</emphasis>
1506 Both functions take an &odr; stream as parameter. This stream is used to
1507 allocate memory for the data elements, which is released on a
1508 subsequent call to <function>odr_reset()</function> on that stream.
1512 The OID module provides a higher-level representation of the
1513 family of object identifiers which describe the Z39.50 protocol and its
1514 related objects. The definition of the module interface is given in
1515 the <filename>oid.h</filename> file.
1519 The interface is mainly based on the <literal>oident</literal> structure.
1520 The definition of this structure looks like this:
1524 typedef struct oident
1529 int oidsuffix[OID_SIZE];
1535 The proto field takes one of the values
1544 Use <literal>PROTO_Z3950</literal> for Z39.50 Object Identifers,
1545 <literal>PROTO_GENERAL</literal> for other types (such as
1546 those associated with ILL).
1550 The oclass field takes one of the values
1572 corresponding to the OID classes defined by the Z39.50 standard.
1574 Finally, the value field takes one of the values
1632 again, corresponding to the specific OIDs defined by the standard.
1634 <ulink url="&url.z39.50.oids;">
1635 Registry of Z39.50 Object Identifiers</ulink> for the
1640 The desc field contains a brief, mnemonic name for the OID in question.
1648 struct oident *oid_getentbyoid(int *o);
1652 takes as argument an OID, and returns a pointer to a static area
1653 containing an <literal>oident</literal> structure. You typically use
1654 this function when you receive a PDU containing an OID, and you wish
1655 to branch out depending on the specific OID value.
1663 int *oid_ent_to_oid(struct oident *ent, int *dst);
1667 Takes as argument an <literal>oident</literal> structure - in which
1668 the <literal>proto</literal>, <literal>oclass</literal>/, and
1669 <literal>value</literal> fields are assumed to be set correctly -
1670 and returns a pointer to a the buffer as given by <literal>dst</literal>
1672 representation of the corresponding OID. The function returns
1673 NULL and the array dst is unchanged if a mapping couldn't place.
1674 The array <literal>dst</literal> should be at least of size
1675 <literal>OID_SIZE</literal>.
1679 The <function>oid_ent_to_oid()</function> function can be used whenever
1680 you need to prepare a PDU containing one or more OIDs. The separation of
1681 the <literal>protocol</literal> element from the remainder of the
1682 OID-description makes it simple to write applications that can
1683 communicate with either Z39.50 or OSI SR-based applications.
1691 oid_value oid_getvalbyname(const char *name);
1695 takes as argument a mnemonic OID name, and returns the
1696 <literal>/value</literal> field of the first entry in the database that
1697 contains the given name in its <literal>desc</literal> field.
1701 Three utility functions are provided for translating OIDs'
1702 symbolic names (e.g. <literal>Usmarc</literal> into OID structures
1703 (int arrays) and strings containing the OID in dotted notation
1704 (e.g. <literal>1.2.840.10003.9.5.1</literal>). They are:
1708 int *oid_name_to_oid(oid_class oclass, const char *name, int *oid);
1709 char *oid_to_dotstring(const int *oid, char *oidbuf);
1710 char *oid_name_to_dotstring(oid_class oclass, const char *name, char *oidbuf);
1714 <literal>oid_name_to_oid()</literal>
1715 translates the specified symbolic <literal>name</literal>,
1716 interpreted as being of class <literal>oclass</literal>. (The
1717 class must be specified as many symbolic names exist within
1718 multiple classes - for example, <literal>Zthes</literal> is the
1719 symbolic name of an attribute set, a schema and a tag-set.) The
1720 sequence of integers representing the OID is written into the
1721 area <literal>oid</literal> provided by the caller; it is the
1722 caller's responsibility to ensure that this area is large enough
1723 to contain the translated OID. As a convenience, the address of
1724 the buffer (i.e. the value of <literal>oid</literal>) is
1728 <literal>oid_to_dotstring()</literal>
1729 Translates the int-array <literal>oid</literal> into a dotted
1730 string which is written into the area <literal>oidbuf</literal>
1731 supplied by the caller; it is the caller's responsibility to
1732 ensure that this area is large enough. The address of the buffer
1736 <literal>oid_name_to_dotstring()</literal>
1737 combines the previous two functions to derive a dotted string
1738 representing the OID specified by <literal>oclass</literal> and
1739 <literal>name</literal>, writing it into the buffer passed as
1740 <literal>oidbuf</literal> and returning its address.
1744 Finally, the module provides the following utility functions, whose
1745 meaning should be obvious:
1749 void oid_oidcpy(int *t, int *s);
1750 void oid_oidcat(int *t, int *s);
1751 int oid_oidcmp(int *o1, int *o2);
1752 int oid_oidlen(int *o);
1757 The OID module has been criticized - and perhaps rightly so
1758 - for needlessly abstracting the
1759 representation of OIDs. Other toolkits use a simple
1760 string-representation of OIDs with good results. In practice, we have
1761 found the interface comfortable and quick to work with, and it is a
1762 simple matter (for what it's worth) to create applications compatible
1763 with both ISO SR and Z39.50. Finally, the use of the
1764 <literal>/oident</literal> database is by no means mandatory.
1765 You can easily create your own system for representing OIDs, as long
1766 as it is compatible with the low-level integer-array representation
1773 <sect1 id="tools.nmem"><title>Nibble Memory</title>
1776 Sometimes when you need to allocate and construct a large,
1777 interconnected complex of structures, it can be a bit of a pain to
1778 release the associated memory again. For the structures describing the
1779 Z39.50 PDUs and related structures, it is convenient to use the
1780 memory-management system of the &odr; subsystem (see
1781 <xref linkend="odr.use"/>). However, in some circumstances
1782 where you might otherwise benefit from using a simple nibble memory
1783 management system, it may be impractical to use
1784 <function>odr_malloc()</function> and <function>odr_reset()</function>.
1785 For this purpose, the memory manager which also supports the &odr;
1786 streams is made available in the NMEM module. The external interface
1787 to this module is given in the <filename>nmem.h</filename> file.
1791 The following prototypes are given:
1795 NMEM nmem_create(void);
1796 void nmem_destroy(NMEM n);
1797 void *nmem_malloc(NMEM n, int size);
1798 void nmem_reset(NMEM n);
1799 int nmem_total(NMEM n);
1800 void nmem_init(void);
1801 void nmem_exit(void);
1805 The <function>nmem_create()</function> function returns a pointer to a
1806 memory control handle, which can be released again by
1807 <function>nmem_destroy()</function> when no longer needed.
1808 The function <function>nmem_malloc()</function> allocates a block of
1809 memory of the requested size. A call to <function>nmem_reset()</function>
1810 or <function>nmem_destroy()</function> will release all memory allocated
1811 on the handle since it was created (or since the last call to
1812 <function>nmem_reset()</function>. The function
1813 <function>nmem_total()</function> returns the number of bytes currently
1814 allocated on the handle.
1818 The nibble memory pool is shared amongst threads. POSIX
1819 mutex'es and WIN32 Critical sections are introduced to keep the
1820 module thread safe. Function <function>nmem_init()</function>
1821 initializes the nibble memory library and it is called automatically
1822 the first time the <literal>YAZ.DLL</literal> is loaded. &yaz; uses
1823 function <function>DllMain</function> to achieve this. You should
1824 <emphasis>not</emphasis> call <function>nmem_init</function> or
1825 <function>nmem_exit</function> unless you're absolute sure what
1826 you're doing. Note that in previous &yaz; versions you'd have to call
1827 <function>nmem_init</function> yourself.
1832 <sect1 id="tools.log"><title>Log</title>
1834 &yaz; has evolved a fairly complex log system which should be useful both
1835 for debugging &yaz; itself, debugging applications that use &yaz;, and for
1836 production use of those applications.
1839 The log functions are declared in header <filename>yaz/log.h</filename>
1840 and implemented in <filename>src/log.c</filename>.
1841 Due to name clash with syslog and some math utilities the logging
1842 interface has been modified as of YAZ 2.0.29. The obsolete interface
1843 is still available if in header file <filename>yaz/log.h</filename>.
1844 The key points of the interface are:
1847 void yaz_log(int level, const char *fmt, ...)
1849 void yaz_log_init(int level, const char *prefix, const char *name);
1850 void yaz_log_init_file(const char *fname);
1851 void yaz_log_init_level(int level);
1852 void yaz_log_init_prefix(const char *prefix);
1853 void yaz_log_time_format(const char *fmt);
1854 void yaz_log_init_max_size(int mx);
1856 int yaz_log_mask_str(const char *str);
1857 int yaz_log_module_level(const char *name);
1861 The reason for the whole log module is the <function>yaz_log</function>
1862 function. It takes a bitmask indicating the log levels, a
1863 <literal>printf</literal>-like format string, and a variable number of
1868 The <literal>log level</literal> is a bit mask, that says on which level(s)
1869 the log entry should be made, and optionally set some behaviour of the
1870 logging. In the most simple cases, it can be one of <literal>YLOG_FATAL,
1871 YLOG_DEBUG, YLOG_WARN, YLOG_LOG</literal>. Those can be combined with bits
1872 that modify the way the log entry is written:<literal>YLOG_ERRNO,
1873 YLOG_NOTIME, YLOG_FLUSH</literal>.
1874 Most of the rest of the bits are deprecated, and should not be used. Use
1875 the dynamic log levels instead.
1879 Applications that use &yaz;, should not use the LOG_LOG for ordinary
1880 messages, but should make use of the dynamic loglevel system. This consists
1881 of two parts, defining the loglevel and checking it.
1885 To define the log levels, the (main) program should pass a string to
1886 <function>yaz_log_mask_str</function> to define which log levels are to be
1887 logged. This string should be a comma-separated list of log level names,
1888 and can contain both hard-coded names and dynamic ones. The log level
1889 calculation starts with <literal>YLOG_DEFAULT_LEVEL</literal> and adds a bit
1890 for each word it meets, unless the word starts with a '-', in which case it
1891 clears the bit. If the string <literal>'none'</literal> is found,
1892 all bits are cleared. Typically this string comes from the command-line,
1893 often identified by <literal>-v</literal>. The
1894 <function>yaz_log_mask_str</function> returns a log level that should be
1895 passed to <function>yaz_log_init_level</function> for it to take effect.
1899 Each module should check what log bits it should be used, by calling
1900 <function>yaz_log_module_level</function> with a suitable name for the
1901 module. The name is cleared from a preceding path and an extension, if any,
1902 so it is quite possible to use <literal>__FILE__</literal> for it. If the
1903 name has been passed to <function>yaz_log_mask_str</function>, the routine
1904 returns a non-zero bitmask, which should then be used in consequent calls
1905 to yaz_log. (It can also be tested, so as to avoid unnecessary calls to
1906 yaz_log, in time-critical places, or when the log entry would take time
1911 Yaz uses the following dynamic log levels:
1912 <literal>server, session, request, requestdetail</literal> for the server
1914 <literal>zoom</literal> for the zoom client api.
1915 <literal>ztest</literal> for the simple test server.
1916 <literal>malloc, nmem, odr, eventl</literal> for internal debugging of yaz itself.
1917 Of course, any program using yaz is welcome to define as many new ones, as
1922 By default the log is written to stderr, but this can be changed by a call
1923 to <function>yaz_log_init_file</function> or
1924 <function>yaz_log_init</function>. If the log is directed to a file, the
1925 file size is checked at every write, and if it exceeds the limit given in
1926 <function>yaz_log_init_max_size</function>, the log is rotated. The
1927 rotation keeps one old version (with a <literal>.1</literal> appended to
1928 the name). The size defaults to 1GB. Setting it to zero will disable the
1933 A typical yaz-log looks like this
1934 13:23:14-23/11 yaz-ztest(1) [session] Starting session from tcp:127.0.0.1 (pid=30968)
1935 13:23:14-23/11 yaz-ztest(1) [request] Init from 'YAZ' (81) (ver 2.0.28) OK
1936 13:23:17-23/11 yaz-ztest(1) [request] Search Z: @attrset Bib-1 foo OK:7 hits
1937 13:23:22-23/11 yaz-ztest(1) [request] Present: [1] 2+2 OK 2 records returned
1938 13:24:13-23/11 yaz-ztest(1) [request] Close OK
1942 The log entries start with a time stamp. This can be omitted by setting the
1943 <literal>YLOG_NOTIME</literal> bit in the loglevel. This way automatic tests
1944 can be hoped to produce identical log files, that are easy to diff. The
1945 format of the time stamp can be set with
1946 <function>yaz_log_time_format</function>, which takes a format string just
1947 like <function>strftime</function>.
1951 Next in a log line comes the prefix, often the name of the program. For
1952 yaz-based servers, it can also contain the session number. Then
1953 comes one or more logbits in square brackets, depending on the logging
1954 level set by <function>yaz_log_init_level</function> and the loglevel
1955 passed to <function>yaz_log_init_level</function>. Finally comes the format
1956 string and additional values passed to <function>yaz_log</function>
1960 The log level <literal>YLOG_LOGLVL</literal>, enabled by the string
1961 <literal>loglevel</literal>, will log all the log-level affecting
1962 operations. This can come in handy if you need to know what other log
1963 levels would be useful. Grep the logfile for <literal>[loglevel]</literal>.
1967 The log system is almost independent of the rest of &yaz;, the only
1968 important dependence is of <filename>nmem</filename>, and that only for
1969 using the semaphore definition there.
1973 The dynamic log levels and log rotation were introduced in &yaz; 2.0.28. At
1974 the same time, the log bit names were changed from
1975 <literal>LOG_something</literal> to <literal>YLOG_something</literal>,
1976 to avoid collision with <filename>syslog.h</filename>.
1981 <sect1 id="marc"><title>MARC</title>
1984 YAZ provides a fast utility that decodes MARC records and
1985 encodes to a varity of output formats. The MARC records must
1986 be encoded in ISO2709.
1989 #include <yaz/marcdisp.h>
1991 /* create handler */
1992 yaz_marc_t yaz_marc_create(void);
1994 void yaz_marc_destroy(yaz_marc_t mt);
1996 /* set XML mode YAZ_MARC_LINE, YAZ_MARC_SIMPLEXML, ... */
1997 void yaz_marc_xml(yaz_marc_t mt, int xmlmode);
1998 #define YAZ_MARC_LINE 0
1999 #define YAZ_MARC_SIMPLEXML 1
2000 #define YAZ_MARC_OAIMARC 2
2001 #define YAZ_MARC_MARCXML 3
2002 #define YAZ_MARC_ISO2709 4
2003 #define YAZ_MARC_XCHANGE 5
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 char **result, int *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);
2023 A MARC conversion handle must be created by using
2024 <function>yaz_marc_create</function> and destroyed
2025 by calling <function>yaz_marc_destroy</function>.
2028 All other function operate on a <literal>yaz_marc_t</literal> handle.
2029 The output is specified by a call to <function>yaz_marc_xml</function>.
2030 The <literal>xmlmode</literal> must be one of
2033 <term>YAZ_MARC_LINE</term>
2036 A simple line-by-line format suitable for display but not
2037 recommend for further (machine) processing.
2043 <term>YAZ_MARC_MARCXML</term>
2046 The resulting record is converted to MARCXML.
2052 <term>YAZ_MARC_ISO2709</term>
2055 The resulting record is converted to ISO2709 (MARC).
2062 The actual conversion functions are
2063 <function>yaz_marc_decode_buf</function> and
2064 <function>yaz_marc_decode_wrbuf</function> which decodes and encodes
2065 a MARC record. The former function operates on simple buffers, the
2066 stores the resulting record in a WRBUF handle (WRBUF is a simple string
2069 <example id="example.marc.display">
2070 <title>Display of MARC record</title>
2072 The followint program snippet illustrates how the MARC API may
2073 be used to convert a MARC record to the line-by-line format:
2074 <programlisting><![CDATA[
2075 void print_marc(const char *marc_buf, int marc_buf_size)
2077 char *result; /* for result buf */
2078 int result_len; /* for size of result */
2079 yaz_marc_t mt = yaz_marc_create();
2080 yaz_marc_xml(mt, YAZ_MARC_LINE);
2081 yaz_marc_decode_buf(mt, marc_buf, marc_buf_size,
2082 &result, &result_len);
2083 fwrite(result, result_len, 1, stdout);
2084 yaz_marc_destroy(mt); /* note that result is now freed... */
2094 <!-- Keep this comment at the end of the file
2099 sgml-minimize-attributes:nil
2100 sgml-always-quote-attributes:t
2103 sgml-parent-document: "yaz.xml"
2104 sgml-local-catalogs: nil
2105 sgml-namecase-general:t