1 <!-- $Id: tools.xml,v 1.50 2006-06-13 16:01:51 adam Exp $ -->
2 <chapter id="tools"><title>Supporting Tools</title>
5 In support of the service API - primarily the ASN module, which
6 provides the pro-grammatic interface to the Z39.50 APDUs, &yaz; contains
7 a collection of tools that support the development of applications.
10 <sect1 id="tools.query"><title>Query Syntax Parsers</title>
13 Since the type-1 (RPN) query structure has no direct, useful string
14 representation, every origin application needs to provide some form of
15 mapping from a local query notation or representation to a
16 <token>Z_RPNQuery</token> structure. Some programmers will prefer to
17 construct the query manually, perhaps using
18 <function>odr_malloc()</function> to simplify memory management.
19 The &yaz; distribution includes three separate, query-generating tools
20 that may be of use to you.
23 <sect2 id="PQF"><title>Prefix Query Format</title>
26 Since RPN or reverse polish notation is really just a fancy way of
27 describing a suffix notation format (operator follows operands), it
28 would seem that the confusion is total when we now introduce a prefix
29 notation for RPN. The reason is one of simple laziness - it's somewhat
30 simpler to interpret a prefix format, and this utility was designed
31 for maximum simplicity, to provide a baseline representation for use
32 in simple test applications and scripting environments (like Tcl). The
33 demonstration client included with YAZ uses the PQF.
38 The PQF have been adopted by other parties developing Z39.50
39 software. It is often referred to as Prefix Query Notation
44 The PQF is defined by the pquery module in the YAZ library.
45 There are two sets of function that have similar behavior. First
46 set operates on a PQF parser handle, second set doesn't. First set
47 set of functions are more flexible than the second set. Second set
48 is obsolete and is only provided to ensure backwards compatibility.
51 First set of functions all operate on a PQF parser handle:
54 #include <yaz/pquery.h>
56 YAZ_PQF_Parser yaz_pqf_create (void);
58 void yaz_pqf_destroy (YAZ_PQF_Parser p);
60 Z_RPNQuery *yaz_pqf_parse (YAZ_PQF_Parser p, ODR o, const char *qbuf);
62 Z_AttributesPlusTerm *yaz_pqf_scan (YAZ_PQF_Parser p, ODR o,
63 Odr_oid **attributeSetId, const char *qbuf);
66 int yaz_pqf_error (YAZ_PQF_Parser p, const char **msg, size_t *off);
69 A PQF parser is created and destructed by functions
70 <function>yaz_pqf_create</function> and
71 <function>yaz_pqf_destroy</function> respectively.
72 Function <function>yaz_pqf_parse</function> parses query given
73 by string <literal>qbuf</literal>. If parsing was successful,
74 a Z39.50 RPN Query is returned which is created using ODR stream
75 <literal>o</literal>. If parsing failed, a NULL pointer is
77 Function <function>yaz_pqf_scan</function> takes a scan query in
78 <literal>qbuf</literal>. If parsing was successful, the function
79 returns attributes plus term pointer and modifies
80 <literal>attributeSetId</literal> to hold attribute set for the
81 scan request - both allocated using ODR stream <literal>o</literal>.
82 If parsing failed, yaz_pqf_scan returns a NULL pointer.
83 Error information for bad queries can be obtained by a call to
84 <function>yaz_pqf_error</function> which returns an error code and
85 modifies <literal>*msg</literal> to point to an error description,
86 and modifies <literal>*off</literal> to the offset within last
87 query were parsing failed.
90 The second set of functions are declared as follows:
93 #include <yaz/pquery.h>
95 Z_RPNQuery *p_query_rpn (ODR o, oid_proto proto, const char *qbuf);
97 Z_AttributesPlusTerm *p_query_scan (ODR o, oid_proto proto,
98 Odr_oid **attributeSetP, const char *qbuf);
100 int p_query_attset (const char *arg);
103 The function <function>p_query_rpn()</function> takes as arguments an
104 &odr; stream (see section <link linkend="odr">The ODR Module</link>)
105 to provide a memory source (the structure created is released on
106 the next call to <function>odr_reset()</function> on the stream), a
107 protocol identifier (one of the constants <token>PROTO_Z3950</token> and
108 <token>PROTO_SR</token>), an attribute set reference, and
109 finally a null-terminated string holding the query string.
112 If the parse went well, <function>p_query_rpn()</function> returns a
113 pointer to a <literal>Z_RPNQuery</literal> structure which can be
114 placed directly into a <literal>Z_SearchRequest</literal>.
115 If parsing failed, due to syntax error, a NULL pointer is returned.
118 The <literal>p_query_attset</literal> specifies which attribute set
119 to use if the query doesn't specify one by the
120 <literal>@attrset</literal> operator.
121 The <literal>p_query_attset</literal> returns 0 if the argument is a
122 valid attribute set specifier; otherwise the function returns -1.
126 The grammar of the PQF is as follows:
130 query ::= top-set query-struct.
132 top-set ::= [ '@attrset' string ]
134 query-struct ::= attr-spec | simple | complex | '@term' term-type query
136 attr-spec ::= '@attr' [ string ] string query-struct
138 complex ::= operator query-struct query-struct.
140 operator ::= '@and' | '@or' | '@not' | '@prox' proximity.
142 simple ::= result-set | term.
144 result-set ::= '@set' string.
148 proximity ::= exclusion distance ordered relation which-code unit-code.
150 exclusion ::= '1' | '0' | 'void'.
152 distance ::= integer.
154 ordered ::= '1' | '0'.
156 relation ::= integer.
158 which-code ::= 'known' | 'private' | integer.
160 unit-code ::= integer.
162 term-type ::= 'general' | 'numeric' | 'string' | 'oid' | 'datetime' | 'null'.
166 You will note that the syntax above is a fairly faithful
167 representation of RPN, except for the Attribute, which has been
168 moved a step away from the term, allowing you to associate one or more
169 attributes with an entire query structure. The parser will
170 automatically apply the given attributes to each term as required.
174 The @attr operator is followed by an attribute specification
175 (<literal>attr-spec</literal> above). The specification consists
176 of an optional attribute set, an attribute type-value pair and
177 a sub-query. The attribute type-value pair is packed in one string:
178 an attribute type, an equals sign, and an attribute value, like this:
179 <literal>@attr 1=1003</literal>.
180 The type is always an integer but the value may be either an
181 integer or a string (if it doesn't start with a digit character).
182 A string attribute-value is encoded as a Type-1 ``complex''
183 attribute with the list of values containing the single string
184 specified, and including no semantic indicators.
188 Version 3 of the Z39.50 specification defines various encoding of terms.
189 Use <literal>@term </literal> <replaceable>type</replaceable>
190 <replaceable>string</replaceable>,
191 where type is one of: <literal>general</literal>,
192 <literal>numeric</literal> or <literal>string</literal>
193 (for InternationalString).
194 If no term type has been given, the <literal>general</literal> form
195 is used. This is the only encoding allowed in both versions 2 and 3
196 of the Z39.50 standard.
199 <sect3 id="PQF-prox">
200 <title>Using Proximity Operators with PQF</title>
203 This is an advanced topic, describing how to construct
204 queries that make very specific requirements on the
205 relative location of their operands.
206 You may wish to skip this section and go straight to
207 <link linkend="pqf-examples">the example PQF queries</link>.
212 Most Z39.50 servers do not support proximity searching, or
213 support only a small subset of the full functionality that
214 can be expressed using the PQF proximity operator. Be
215 aware that the ability to <emphasis>express</emphasis> a
216 query in PQF is no guarantee that any given server will
217 be able to <emphasis>execute</emphasis> it.
223 The proximity operator <literal>@prox</literal> is a special
224 and more restrictive version of the conjunction operator
225 <literal>@and</literal>. Its semantics are described in
226 section 3.7.2 (Proximity) of Z39.50 the standard itself, which
227 can be read on-line at
228 <ulink url="&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><title>PQF queries using simple terms</title>
313 <example><title>PQF boolean operators</title>
316 @or "dylan" "zimmerman"
318 @and @or dylan zimmerman when
320 @and when @or dylan zimmerman
324 <example><title>PQF references to result sets</title>
329 @and @set seta @set setb
333 <example><title>Attributes for terms</title>
338 @attr 1=4 @attr 4=1 "self portrait"
340 @attrset exp1 @attr 1=1 CategoryList
342 @attr gils 1=2008 Copenhagen
344 @attr 1=/book/title computer
348 <example><title>PQF Proximity queries</title>
351 @prox 0 3 1 2 k 2 dylan zimmerman
354 Here the parameters 0, 3, 1, 2, k and 2 represent exclusion,
355 distance, ordered, relation, which-code and unit-code, in that
359 exclusion = 0: the proximity condition must hold
362 distance = 3: the terms must be three units apart
365 ordered = 1: they must occur in the order they are specified
368 relation = 2: lessThanOrEqual (to the distance of 3 units)
371 which-code is ``known'', so the standard unit-codes are used
377 So the whole proximity query means that the words
378 <literal>dylan</literal> and <literal>zimmerman</literal> must
379 both occur in the record, in that order, differing in position
380 by three or fewer words (i.e. with two or fewer words between
381 them.) The query would find ``Bob Dylan, aka. Robert
382 Zimmerman'', but not ``Bob Dylan, born as Robert Zimmerman''
383 since the distance in this case is four.
387 <example><title>PQF specification of search term</title>
390 @term string "a UTF-8 string, maybe?"
394 <example><title>PQF mixed queries</title>
397 @or @and bob dylan @set Result-1
399 @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming"
401 @and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109
405 The last of these examples is a spatial search: in
406 <ulink url="http://www.gils.net/prof_v2.html#sec_7_4"
407 >the GILS attribute set</ulink>,
409 2038 indicates West Bounding Coordinate and
410 2030 indicates East Bounding Coordinate,
411 so the query is for areas extending from -114 degrees
412 to no more than -109 degrees.
419 <sect2 id="CCL"><title>CCL</title>
422 Not all users enjoy typing in prefix query structures and numerical
423 attribute values, even in a minimalistic test client. In the library
424 world, the more intuitive Common Command Language - CCL (ISO 8777)
425 has enjoyed some popularity - especially before the widespread
426 availability of graphical interfaces. It is still useful in
427 applications where you for some reason or other need to provide a
428 symbolic language for expressing boolean query structures.
432 The EUROPAGATE research project working under the Libraries programme
433 of the European Commission's DG XIII has, amongst other useful tools,
434 implemented a general-purpose CCL parser which produces an output
435 structure that can be trivially converted to the internal RPN
436 representation of &yaz; (The <literal>Z_RPNQuery</literal> structure).
437 Since the CCL utility - along with the rest of the software
438 produced by EUROPAGATE - is made freely available on a liberal
439 license, it is included as a supplement to &yaz;.
442 <sect3><title>CCL Syntax</title>
445 The CCL parser obeys the following grammar for the FIND argument.
446 The syntax is annotated by in the lines prefixed by
447 <literal>‐‐</literal>.
451 CCL-Find ::= CCL-Find Op Elements
454 Op ::= "and" | "or" | "not"
455 -- The above means that Elements are separated by boolean operators.
457 Elements ::= '(' CCL-Find ')'
460 | Qualifiers Relation Terms
461 | Qualifiers Relation '(' CCL-Find ')'
462 | Qualifiers '=' string '-' string
463 -- Elements is either a recursive definition, a result set reference, a
464 -- list of terms, qualifiers followed by terms, qualifiers followed
465 -- by a recursive definition or qualifiers in a range (lower - upper).
467 Set ::= 'set' = string
468 -- Reference to a result set
470 Terms ::= Terms Prox Term
472 -- Proximity of terms.
476 -- This basically means that a term may include a blank
478 Qualifiers ::= Qualifiers ',' string
480 -- Qualifiers is a list of strings separated by comma
482 Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<'
483 -- Relational operators. This really doesn't follow the ISO8777
487 -- Proximity operator
491 <example><title>CCL queries</title>
493 The following queries are all valid:
505 (dylan and bob) or set=1
509 Assuming that the qualifiers <literal>ti</literal>,
510 <literal>au</literal>
511 and <literal>date</literal> are defined we may use:
517 au=(bob dylan and slow train coming)
519 date>1980 and (ti=((self portrait)))
525 <sect3><title>CCL Qualifiers</title>
528 Qualifiers are used to direct the search to a particular searchable
529 index, such as title (ti) and author indexes (au). The CCL standard
530 itself doesn't specify a particular set of qualifiers, but it does
531 suggest a few short-hand notations. You can customize the CCL parser
532 to support a particular set of qualifiers to reflect the current target
533 profile. Traditionally, a qualifier would map to a particular
534 use-attribute within the BIB-1 attribute set. It is also
535 possible to set other attributes, such as the structure
540 A CCL profile is a set of predefined CCL qualifiers that may be
541 read from a file or set in the CCL API.
542 The YAZ client reads its CCL qualifiers from a file named
543 <filename>default.bib</filename>. There are four types of
544 lines in a CCL profile: qualifier specification,
545 qualifier alias, comments and directives.
547 <sect4><title id="qualifier-specification">Qualifier specification</title>
549 A qualifier specification is of the form:
553 <replaceable>qualifier-name</replaceable>
554 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable>
555 [<replaceable>attributeset</replaceable><literal>,</literal>]<replaceable>type</replaceable><literal>=</literal><replaceable>val</replaceable> ...
559 where <replaceable>qualifier-name</replaceable> is the name of the
560 qualifier to be used (eg. <literal>ti</literal>),
561 <replaceable>type</replaceable> is attribute type in the attribute
562 set (Bib-1 is used if no attribute set is given) and
563 <replaceable>val</replaceable> is attribute value.
564 The <replaceable>type</replaceable> can be specified as an
565 integer or as it be specified either as a single-letter:
566 <literal>u</literal> for use,
567 <literal>r</literal> for relation,<literal>p</literal> for position,
568 <literal>s</literal> for structure,<literal>t</literal> for truncation
569 or <literal>c</literal> for completeness.
570 The attributes for the special qualifier name <literal>term</literal>
571 are used when no CCL qualifier is given in a query.
572 <table><title>Common Bib-1 attributes</title>
574 <colspec colwidth="2*" colname="type"></colspec>
575 <colspec colwidth="9*" colname="description"></colspec>
579 <entry>Description</entry>
584 <entry><literal>u=</literal><replaceable>value</replaceable></entry>
586 Use attribute (1). Common use attributes are
587 1 Personal-name, 4 Title, 7 ISBN, 8 ISSN, 30 Date,
588 62 Subject, 1003 Author), 1016 Any. Specify value
594 <entry><literal>r=</literal><replaceable>value</replaceable></entry>
596 Relation attribute (2). Common values are
597 1 <, 2 <=, 3 =, 4 >=, 5 >, 6 <>,
598 100 phonetic, 101 stem, 102 relevance, 103 always matches.
603 <entry><literal>p=</literal><replaceable>value</replaceable></entry>
605 Position attribute (3). Values: 1 first in field, 2
606 first in any subfield, 3 any position in field.
611 <entry><literal>s=</literal><replaceable>value</replaceable></entry>
613 Structure attribute (4). Values: 1 phrase, 2 word,
614 3 key, 4 year, 5 date, 6 word list, 100 date (un),
615 101 name (norm), 102 name (un), 103 structure, 104 urx,
616 105 free-form-text, 106 document-text, 107 local-number,
617 108 string, 109 numeric string.
622 <entry><literal>t=</literal><replaceable>value</replaceable></entry>
624 Truncation attribute (5). Values: 1 right, 2 left,
625 3 left& right, 100 none, 101 process #, 102 regular-1,
626 103 regular-2, 104 CCL.
631 <entry><literal>c=</literal><replaceable>value</replaceable></entry>
633 Completeness attribute (6). Values: 1 incomplete subfield,
634 2 complete subfield, 3 complete field.
643 Refer to the complete
644 <ulink url="&url.z39.50.attset.bib1;">list of Bib-1 attributes</ulink>
647 It is also possible to specify non-numeric attribute values,
648 which are used in combination with certain types.
649 The special combinations are:
651 <table><title>Special attribute combos</title>
653 <colspec colwidth="2*" colname="name"></colspec>
654 <colspec colwidth="9*" colname="description"></colspec>
658 <entry>Description</entry>
663 <entry><literal>s=pw</literal></entry><entry>
664 The structure is set to either word or phrase depending
665 on the number of tokens in a term (phrase-word).
669 <entry><literal>s=al</literal></entry><entry>
670 Each token in the term is ANDed. (and-list).
671 This does not set the structure at all.
675 <row><entry><literal>s=ol</literal></entry><entry>
676 Each token in the term is ORed. (or-list).
677 This does not set the structure at all.
681 <row><entry><literal>r=o</literal></entry><entry>
682 Allows ranges and the operators greather-than, less-than, ...
684 This sets Bib-1 relation attribute accordingly (relation
685 ordered). A query construct is only treated as a range if
686 dash is used and that is surrounded by white-space. So
687 <literal>-1980</literal> is treated as term
688 <literal>"-1980"</literal> not <literal><= 1980</literal>.
689 If <literal>- 1980</literal> is used, however, that is
694 <row><entry><literal>r=r</literal></entry><entry>
695 Similar to <literal>r=o</literal> but assumes that terms
696 are non-negative (not prefixed with <literal>-</literal>).
697 Thus, a dash will always be treated as a range.
698 The construct <literal>1980-1990</literal> is
699 treated as a range with <literal>r=r</literal> but as a
700 single term <literal>"1980-1990"</literal> with
701 <literal>r=o</literal>. The special attribute
702 <literal>r=r</literal> is available in YAZ 2.0.24 or later.
706 <row><entry><literal>t=l</literal></entry><entry>
707 Allows term to be left-truncated.
708 If term is of the form <literal>?x</literal>, the resulting
709 Type-1 term is <literal>x</literal> and truncation is left.
713 <row><entry><literal>t=r</literal></entry><entry>
714 Allows term to be right-truncated.
715 If term is of the form <literal>x?</literal>, the resulting
716 Type-1 term is <literal>x</literal> and truncation is right.
720 <row><entry><literal>t=n</literal></entry><entry>
721 If term is does not include <literal>?</literal>, the
722 truncation attribute is set to none (100).
726 <row><entry><literal>t=b</literal></entry><entry>
727 Allows term to be both left&right truncated.
728 If term is of the form <literal>?x?</literal>, the
729 resulting term is <literal>x</literal> and trunctation is
730 set to both left&right.
737 <example><title>CCL profile</title>
739 Consider the following definition:
750 <literal>ti</literal> and <literal>au</literal> both set
751 structure attribute to phrase (s=1).
752 <literal>ti</literal>
753 sets the use-attribute to 4. <literal>au</literal> sets the
755 When no qualifiers are used in the query the structure-attribute is
756 set to free-form-text (105) (rule for <literal>term</literal>).
757 The <literal>date</literal> sets the relation attribute to
758 the relation used in the CCL query and sets the use attribute
762 You can combine attributes. To Search for "ranked title" you
765 ti,ranked=knuth computer
767 which will set relation=ranked, use=title, structure=phrase.
774 is a valid query. But
782 <sect4><title>Qualifier alias</title>
784 A qualifier alias is of the form:
787 <replaceable>q</replaceable>
788 <replaceable>q1</replaceable> <replaceable>q2</replaceable> ..
791 which declares <replaceable>q</replaceable> to
792 be an alias for <replaceable>q1</replaceable>,
793 <replaceable>q2</replaceable>... such that the CCL
794 query <replaceable>q=x</replaceable> is equivalent to
795 <replaceable>q1=x or q2=x or ...</replaceable>.
799 <sect4><title>Comments</title>
801 Lines with white space or lines that begin with
802 character <literal>#</literal> are treated as comments.
806 <sect4><title>Directives</title>
808 Directive specifications takes the form
810 <para><literal>@</literal><replaceable>directive</replaceable> <replaceable>value</replaceable>
812 <table><title>CCL directives</title>
814 <colspec colwidth="2*" colname="name"></colspec>
815 <colspec colwidth="8*" colname="description"></colspec>
816 <colspec colwidth="1*" colname="default"></colspec>
820 <entry>Description</entry>
821 <entry>Default</entry>
826 <entry>truncation</entry>
827 <entry>Truncation character</entry>
828 <entry><literal>?</literal></entry>
832 <entry>Specifies how multiple fields are to be
833 combined. There are two modes: <literal>or</literal>:
834 multiple qualifier fields are ORed,
835 <literal>merge</literal>: attributes for the qualifier
836 fields are merged and assigned to one term.
838 <entry><literal>merge</literal></entry>
842 <entry>Specificies if CCL operatores and qualifiers should be
843 compared with case sensitivity or not. Specify 0 for
844 case sensitive; 1 for case insensitive.</entry>
845 <entry><literal>0</literal></entry>
850 <entry>Specifies token for CCL operator AND.</entry>
851 <entry><literal>and</literal></entry>
856 <entry>Specifies token for CCL operator OR.</entry>
857 <entry><literal>or</literal></entry>
862 <entry>Specifies token for CCL operator NOT.</entry>
863 <entry><literal>not</literal></entry>
868 <entry>Specifies token for CCL operator SET.</entry>
869 <entry><literal>set</literal></entry>
876 <sect3><title>CCL API</title>
878 All public definitions can be found in the header file
879 <filename>ccl.h</filename>. A profile identifier is of type
880 <literal>CCL_bibset</literal>. A profile must be created with the call
881 to the function <function>ccl_qual_mk</function> which returns a profile
882 handle of type <literal>CCL_bibset</literal>.
886 To read a file containing qualifier definitions the function
887 <function>ccl_qual_file</function> may be convenient. This function
888 takes an already opened <literal>FILE</literal> handle pointer as
889 argument along with a <literal>CCL_bibset</literal> handle.
893 To parse a simple string with a FIND query use the function
896 struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str,
897 int *error, int *pos);
900 which takes the CCL profile (<literal>bibset</literal>) and query
901 (<literal>str</literal>) as input. Upon successful completion the RPN
902 tree is returned. If an error occur, such as a syntax error, the integer
903 pointed to by <literal>error</literal> holds the error code and
904 <literal>pos</literal> holds the offset inside query string in which
909 An English representation of the error may be obtained by calling
910 the <literal>ccl_err_msg</literal> function. The error codes are
911 listed in <filename>ccl.h</filename>.
915 To convert the CCL RPN tree (type
916 <literal>struct ccl_rpn_node *</literal>)
917 to the Z_RPNQuery of YAZ the function <function>ccl_rpn_query</function>
918 must be used. This function which is part of YAZ is implemented in
919 <filename>yaz-ccl.c</filename>.
920 After calling this function the CCL RPN tree is probably no longer
921 needed. The <literal>ccl_rpn_delete</literal> destroys the CCL RPN tree.
925 A CCL profile may be destroyed by calling the
926 <function>ccl_qual_rm</function> function.
930 The token names for the CCL operators may be changed by setting the
931 globals (all type <literal>char *</literal>)
932 <literal>ccl_token_and</literal>, <literal>ccl_token_or</literal>,
933 <literal>ccl_token_not</literal> and <literal>ccl_token_set</literal>.
934 An operator may have aliases, i.e. there may be more than one name for
935 the operator. To do this, separate each alias with a space character.
939 <sect2 id="tools.cql"><title>CQL</title>
941 <ulink url="&url.cql;">CQL</ulink>
942 - Common Query Language - was defined for the
943 <ulink url="&url.sru;">SRU</ulink> protocol.
944 In many ways CQL has a similar syntax to CCL.
945 The objective of CQL is different. Where CCL aims to be
946 an end-user language, CQL is <emphasis>the</emphasis> protocol
947 query language for SRU.
951 If you are new to CQL, read the
952 <ulink url="&url.cql.intro;">Gentle Introduction</ulink>.
956 The CQL parser in &yaz; provides the following:
960 It parses and validates a CQL query.
965 It generates a C structure that allows you to convert
966 a CQL query to some other query language, such as SQL.
971 The parser converts a valid CQL query to PQF, thus providing a
972 way to use CQL for both SRU servers and Z39.50 targets at the
978 The parser converts CQL to
979 <ulink url="&url.xcql;">XCQL</ulink>.
980 XCQL is an XML representation of CQL.
981 XCQL is part of the SRU specification. However, since SRU
982 supports CQL only, we don't expect XCQL to be widely used.
983 Furthermore, CQL has the advantage over XCQL that it is
989 <sect3 id="tools.cql.parsing"><title>CQL parsing</title>
991 A CQL parser is represented by the <literal>CQL_parser</literal>
992 handle. Its contents should be considered &yaz; internal (private).
994 #include <yaz/cql.h>
996 typedef struct cql_parser *CQL_parser;
998 CQL_parser cql_parser_create(void);
999 void cql_parser_destroy(CQL_parser cp);
1001 A parser is created by <function>cql_parser_create</function> and
1002 is destroyed by <function>cql_parser_destroy</function>.
1005 To parse a CQL query string, the following function
1008 int cql_parser_string(CQL_parser cp, const char *str);
1010 A CQL query is parsed by the <function>cql_parser_string</function>
1011 which takes a query <parameter>str</parameter>.
1012 If the query was valid (no syntax errors), then zero is returned;
1013 otherwise -1 is returned to indicate a syntax error.
1017 int cql_parser_stream(CQL_parser cp,
1018 int (*getbyte)(void *client_data),
1019 void (*ungetbyte)(int b, void *client_data),
1022 int cql_parser_stdio(CQL_parser cp, FILE *f);
1024 The functions <function>cql_parser_stream</function> and
1025 <function>cql_parser_stdio</function> parses a CQL query
1026 - just like <function>cql_parser_string</function>.
1027 The only difference is that the CQL query can be
1028 fed to the parser in different ways.
1029 The <function>cql_parser_stream</function> uses a generic
1030 byte stream as input. The <function>cql_parser_stdio</function>
1031 uses a <literal>FILE</literal> handle which is opened for reading.
1035 <sect3 id="tools.cql.tree"><title>CQL tree</title>
1037 The the query string is valid, the CQL parser
1038 generates a tree representing the structure of the
1043 struct cql_node *cql_parser_result(CQL_parser cp);
1045 <function>cql_parser_result</function> returns the
1046 a pointer to the root node of the resulting tree.
1049 Each node in a CQL tree is represented by a
1050 <literal>struct cql_node</literal>.
1051 It is defined as follows:
1053 #define CQL_NODE_ST 1
1054 #define CQL_NODE_BOOL 2
1064 struct cql_node *modifiers;
1068 struct cql_node *left;
1069 struct cql_node *right;
1070 struct cql_node *modifiers;
1075 There are two node types: search term (ST) and boolean (BOOL).
1076 A modifier is treated as a search term too.
1079 The search term node has five members:
1083 <literal>index</literal>: index for search term.
1084 If an index is unspecified for a search term,
1085 <literal>index</literal> will be NULL.
1090 <literal>index_uri</literal>: index URi for search term
1091 or NULL if none could be resolved for the index.
1096 <literal>term</literal>: the search term itself.
1101 <literal>relation</literal>: relation for search term.
1106 <literal>relation_uri</literal>: relation URI for search term.
1111 <literal>modifiers</literal>: relation modifiers for search
1112 term. The <literal>modifiers</literal> list itself of cql_nodes
1113 each of type <literal>ST</literal>.
1120 The boolean node represents both <literal>and</literal>,
1121 <literal>or</literal>, not as well as
1126 <literal>left</literal> and <literal>right</literal>: left
1127 - and right operand respectively.
1132 <literal>modifiers</literal>: proximity arguments.
1139 <sect3 id="tools.cql.pqf"><title>CQL to PQF conversion</title>
1141 Conversion to PQF (and Z39.50 RPN) is tricky by the fact
1142 that the resulting RPN depends on the Z39.50 target
1143 capabilities (combinations of supported attributes).
1144 In addition, the CQL and SRU operates on index prefixes
1145 (URI or strings), whereas the RPN uses Object Identifiers
1149 The CQL library of &yaz; defines a <literal>cql_transform_t</literal>
1150 type. It represents a particular mapping between CQL and RPN.
1151 This handle is created and destroyed by the functions:
1153 cql_transform_t cql_transform_open_FILE (FILE *f);
1154 cql_transform_t cql_transform_open_fname(const char *fname);
1155 void cql_transform_close(cql_transform_t ct);
1157 The first two functions create a tranformation handle from
1158 either an already open FILE or from a filename respectively.
1161 The handle is destroyed by <function>cql_transform_close</function>
1162 in which case no further reference of the handle is allowed.
1165 When a <literal>cql_transform_t</literal> handle has been created
1166 you can convert to RPN.
1168 int cql_transform_buf(cql_transform_t ct,
1169 struct cql_node *cn, char *out, int max);
1171 This function converts the CQL tree <literal>cn</literal>
1172 using handle <literal>ct</literal>.
1173 For the resulting PQF, you supply a buffer <literal>out</literal>
1174 which must be able to hold at at least <literal>max</literal>
1178 If conversion failed, <function>cql_transform_buf</function>
1179 returns a non-zero SRU error code; otherwise zero is returned
1180 (conversion successful). The meanings of the numeric error
1181 codes are listed in the SRU specifications at
1182 <ulink url="&url.sru.diagnostics.list;"/>
1185 If conversion fails, more information can be obtained by calling
1187 int cql_transform_error(cql_transform_t ct, char **addinfop);
1189 This function returns the most recently returned numeric
1190 error-code and sets the string-pointer at
1191 <literal>*addinfop</literal> to point to a string containing
1192 additional information about the error that occurred: for
1193 example, if the error code is 15 (``Illegal or unsupported context
1194 set''), the additional information is the name of the requested
1195 context set that was not recognised.
1198 The SRU error-codes may be translated into brief human-readable
1199 error messages using
1201 const char *cql_strerror(int code);
1205 If you wish to be able to produce a PQF result in a different
1206 way, there are two alternatives.
1208 void cql_transform_pr(cql_transform_t ct,
1209 struct cql_node *cn,
1210 void (*pr)(const char *buf, void *client_data),
1213 int cql_transform_FILE(cql_transform_t ct,
1214 struct cql_node *cn, FILE *f);
1216 The former function produces output to a user-defined
1217 output stream. The latter writes the result to an already
1218 open <literal>FILE</literal>.
1221 <sect3 id="tools.cql.map">
1222 <title>Specification of CQL to RPN mappings</title>
1224 The file supplied to functions
1225 <function>cql_transform_open_FILE</function>,
1226 <function>cql_transform_open_fname</function> follows
1227 a structure found in many Unix utilities.
1228 It consists of mapping specifications - one per line.
1229 Lines starting with <literal>#</literal> are ignored (comments).
1232 Each line is of the form
1234 <replaceable>CQL pattern</replaceable><literal> = </literal> <replaceable> RPN equivalent</replaceable>
1238 An RPN pattern is a simple attribute list. Each attribute pair
1241 [<replaceable>set</replaceable>] <replaceable>type</replaceable><literal>=</literal><replaceable>value</replaceable>
1243 The attribute <replaceable>set</replaceable> is optional.
1244 The <replaceable>type</replaceable> is the attribute type,
1245 <replaceable>value</replaceable> the attribute value.
1248 The following CQL patterns are recognized:
1250 <varlistentry><term>
1251 <literal>index.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1255 This pattern is invoked when a CQL index, such as
1256 dc.title is converted. <replaceable>set</replaceable>
1257 and <replaceable>name</replaceable> are the context set and index
1259 Typically, the RPN specifies an equivalent use attribute.
1262 For terms not bound by an index the pattern
1263 <literal>index.cql.serverChoice</literal> is used.
1264 Here, the prefix <literal>cql</literal> is defined as
1265 <literal>http://www.loc.gov/zing/cql/cql-indexes/v1.0/</literal>.
1266 If this pattern is not defined, the mapping will fail.
1270 <varlistentry><term>
1271 <literal>qualifier.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1276 For backwards compatibility, this is recognised as a synonym of
1277 <literal>index.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
1281 <varlistentry><term>
1282 <literal>relation.</literal><replaceable>relation</replaceable>
1286 This pattern specifies how a CQL relation is mapped to RPN.
1287 <replaceable>pattern</replaceable> is name of relation
1288 operator. Since <literal>=</literal> is used as
1289 separator between CQL pattern and RPN, CQL relations
1290 including <literal>=</literal> cannot be
1291 used directly. To avoid a conflict, the names
1292 <literal>ge</literal>,
1293 <literal>eq</literal>,
1294 <literal>le</literal>,
1295 must be used for CQL operators, greater-than-or-equal,
1296 equal, less-than-or-equal respectively.
1297 The RPN pattern is supposed to include a relation attribute.
1300 For terms not bound by a relation, the pattern
1301 <literal>relation.scr</literal> is used. If the pattern
1302 is not defined, the mapping will fail.
1305 The special pattern, <literal>relation.*</literal> is used
1306 when no other relation pattern is matched.
1311 <varlistentry><term>
1312 <literal>relationModifier.</literal><replaceable>mod</replaceable>
1316 This pattern specifies how a CQL relation modifier is mapped to RPN.
1317 The RPN pattern is usually a relation attribute.
1322 <varlistentry><term>
1323 <literal>structure.</literal><replaceable>type</replaceable>
1327 This pattern specifies how a CQL structure is mapped to RPN.
1328 Note that this CQL pattern is somewhat to similar to
1329 CQL pattern <literal>relation</literal>.
1330 The <replaceable>type</replaceable> is a CQL relation.
1333 The pattern, <literal>structure.*</literal> is used
1334 when no other structure pattern is matched.
1335 Usually, the RPN equivalent specifies a structure attribute.
1340 <varlistentry><term>
1341 <literal>position.</literal><replaceable>type</replaceable>
1345 This pattern specifies how the anchor (position) of
1346 CQL is mapped to RPN.
1347 The <replaceable>type</replaceable> is one
1348 of <literal>first</literal>, <literal>any</literal>,
1349 <literal>last</literal>, <literal>firstAndLast</literal>.
1352 The pattern, <literal>position.*</literal> is used
1353 when no other position pattern is matched.
1358 <varlistentry><term>
1359 <literal>set.</literal><replaceable>prefix</replaceable>
1363 This specification defines a CQL context set for a given prefix.
1364 The value on the right hand side is the URI for the set -
1365 <emphasis>not</emphasis> RPN. All prefixes used in
1366 index patterns must be defined this way.
1372 <example><title>CQL to RPN mapping file</title>
1374 This simple file defines two context sets, three indexes and three
1375 relations, a position pattern and a default structure.
1377 <programlisting><![CDATA[
1378 set.cql = http://www.loc.gov/zing/cql/context-sets/cql/v1.1/
1379 set.dc = http://www.loc.gov/zing/cql/dc-indexes/v1.0/
1381 index.cql.serverChoice = 1=1016
1382 index.dc.title = 1=4
1383 index.dc.subject = 1=21
1389 position.any = 3=3 6=1
1395 With the mappings above, the CQL query
1399 is converted to the PQF:
1401 @attr 1=1016 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "computer"
1403 by rules <literal>index.cql.serverChoice</literal>,
1404 <literal>relation.scr</literal>, <literal>structure.*</literal>,
1405 <literal>position.any</literal>.
1412 is rejected, since <literal>position.right</literal> is
1418 >my = "http://www.loc.gov/zing/cql/dc-indexes/v1.0/" my.title = x
1422 @attr 1=4 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "x"
1427 <sect3 id="tools.cql.xcql"><title>CQL to XCQL conversion</title>
1429 Conversion from CQL to XCQL is trivial and does not
1430 require a mapping to be defined.
1431 There three functions to choose from depending on the
1432 way you wish to store the resulting output (XML buffer
1435 int cql_to_xml_buf(struct cql_node *cn, char *out, int max);
1436 void cql_to_xml(struct cql_node *cn,
1437 void (*pr)(const char *buf, void *client_data),
1439 void cql_to_xml_stdio(struct cql_node *cn, FILE *f);
1441 Function <function>cql_to_xml_buf</function> converts
1442 to XCQL and stores result in a user supplied buffer of a given
1446 <function>cql_to_xml</function> writes the result in
1447 a user defined output stream.
1448 <function>cql_to_xml_stdio</function> writes to a
1454 <sect1 id="tools.oid"><title>Object Identifiers</title>
1457 The basic YAZ representation of an OID is an array of integers,
1458 terminated with the value -1. The &odr; module provides two
1459 utility-functions to create and copy this type of data elements:
1463 Odr_oid *odr_getoidbystr(ODR o, char *str);
1467 Creates an OID based on a string-based representation using dots (.)
1468 to separate elements in the OID.
1472 Odr_oid *odr_oiddup(ODR odr, Odr_oid *o);
1476 Creates a copy of the OID referenced by the <emphasis>o</emphasis>
1478 Both functions take an &odr; stream as parameter. This stream is used to
1479 allocate memory for the data elements, which is released on a
1480 subsequent call to <function>odr_reset()</function> on that stream.
1484 The OID module provides a higher-level representation of the
1485 family of object identifiers which describe the Z39.50 protocol and its
1486 related objects. The definition of the module interface is given in
1487 the <filename>oid.h</filename> file.
1491 The interface is mainly based on the <literal>oident</literal> structure.
1492 The definition of this structure looks like this:
1496 typedef struct oident
1501 int oidsuffix[OID_SIZE];
1507 The proto field takes one of the values
1516 Use <literal>PROTO_Z3950</literal> for Z39.50 Object Identifers,
1517 <literal>PROTO_GENERAL</literal> for other types (such as
1518 those associated with ILL).
1522 The oclass field takes one of the values
1544 corresponding to the OID classes defined by the Z39.50 standard.
1546 Finally, the value field takes one of the values
1604 again, corresponding to the specific OIDs defined by the standard.
1606 <ulink url="&url.z39.50.oids;">
1607 Registry of Z39.50 Object Identifiers</ulink> for the
1612 The desc field contains a brief, mnemonic name for the OID in question.
1620 struct oident *oid_getentbyoid(int *o);
1624 takes as argument an OID, and returns a pointer to a static area
1625 containing an <literal>oident</literal> structure. You typically use
1626 this function when you receive a PDU containing an OID, and you wish
1627 to branch out depending on the specific OID value.
1635 int *oid_ent_to_oid(struct oident *ent, int *dst);
1639 Takes as argument an <literal>oident</literal> structure - in which
1640 the <literal>proto</literal>, <literal>oclass</literal>/, and
1641 <literal>value</literal> fields are assumed to be set correctly -
1642 and returns a pointer to a the buffer as given by <literal>dst</literal>
1644 representation of the corresponding OID. The function returns
1645 NULL and the array dst is unchanged if a mapping couldn't place.
1646 The array <literal>dst</literal> should be at least of size
1647 <literal>OID_SIZE</literal>.
1651 The <function>oid_ent_to_oid()</function> function can be used whenever
1652 you need to prepare a PDU containing one or more OIDs. The separation of
1653 the <literal>protocol</literal> element from the remainder of the
1654 OID-description makes it simple to write applications that can
1655 communicate with either Z39.50 or OSI SR-based applications.
1663 oid_value oid_getvalbyname(const char *name);
1667 takes as argument a mnemonic OID name, and returns the
1668 <literal>/value</literal> field of the first entry in the database that
1669 contains the given name in its <literal>desc</literal> field.
1673 Three utility functions are provided for translating OIDs'
1674 symbolic names (e.g. <literal>Usmarc</literal> into OID structures
1675 (int arrays) and strings containing the OID in dotted notation
1676 (e.g. <literal>1.2.840.10003.9.5.1</literal>). They are:
1680 int *oid_name_to_oid(oid_class oclass, const char *name, int *oid);
1681 char *oid_to_dotstring(const int *oid, char *oidbuf);
1682 char *oid_name_to_dotstring(oid_class oclass, const char *name, char *oidbuf);
1686 <literal>oid_name_to_oid()</literal>
1687 translates the specified symbolic <literal>name</literal>,
1688 interpreted as being of class <literal>oclass</literal>. (The
1689 class must be specified as many symbolic names exist within
1690 multiple classes - for example, <literal>Zthes</literal> is the
1691 symbolic name of an attribute set, a schema and a tag-set.) The
1692 sequence of integers representing the OID is written into the
1693 area <literal>oid</literal> provided by the caller; it is the
1694 caller's responsibility to ensure that this area is large enough
1695 to contain the translated OID. As a convenience, the address of
1696 the buffer (i.e. the value of <literal>oid</literal>) is
1700 <literal>oid_to_dotstring()</literal>
1701 Translates the int-array <literal>oid</literal> into a dotted
1702 string which is written into the area <literal>oidbuf</literal>
1703 supplied by the caller; it is the caller's responsibility to
1704 ensure that this area is large enough. The address of the buffer
1708 <literal>oid_name_to_dotstring()</literal>
1709 combines the previous two functions to derive a dotted string
1710 representing the OID specified by <literal>oclass</literal> and
1711 <literal>name</literal>, writing it into the buffer passed as
1712 <literal>oidbuf</literal> and returning its address.
1716 Finally, the module provides the following utility functions, whose
1717 meaning should be obvious:
1721 void oid_oidcpy(int *t, int *s);
1722 void oid_oidcat(int *t, int *s);
1723 int oid_oidcmp(int *o1, int *o2);
1724 int oid_oidlen(int *o);
1729 The OID module has been criticized - and perhaps rightly so
1730 - for needlessly abstracting the
1731 representation of OIDs. Other toolkits use a simple
1732 string-representation of OIDs with good results. In practice, we have
1733 found the interface comfortable and quick to work with, and it is a
1734 simple matter (for what it's worth) to create applications compatible
1735 with both ISO SR and Z39.50. Finally, the use of the
1736 <literal>/oident</literal> database is by no means mandatory.
1737 You can easily create your own system for representing OIDs, as long
1738 as it is compatible with the low-level integer-array representation
1745 <sect1 id="tools.nmem"><title>Nibble Memory</title>
1748 Sometimes when you need to allocate and construct a large,
1749 interconnected complex of structures, it can be a bit of a pain to
1750 release the associated memory again. For the structures describing the
1751 Z39.50 PDUs and related structures, it is convenient to use the
1752 memory-management system of the &odr; subsystem (see
1753 <xref linkend="odr.use"/>). However, in some circumstances
1754 where you might otherwise benefit from using a simple nibble memory
1755 management system, it may be impractical to use
1756 <function>odr_malloc()</function> and <function>odr_reset()</function>.
1757 For this purpose, the memory manager which also supports the &odr;
1758 streams is made available in the NMEM module. The external interface
1759 to this module is given in the <filename>nmem.h</filename> file.
1763 The following prototypes are given:
1767 NMEM nmem_create(void);
1768 void nmem_destroy(NMEM n);
1769 void *nmem_malloc(NMEM n, int size);
1770 void nmem_reset(NMEM n);
1771 int nmem_total(NMEM n);
1772 void nmem_init(void);
1773 void nmem_exit(void);
1777 The <function>nmem_create()</function> function returns a pointer to a
1778 memory control handle, which can be released again by
1779 <function>nmem_destroy()</function> when no longer needed.
1780 The function <function>nmem_malloc()</function> allocates a block of
1781 memory of the requested size. A call to <function>nmem_reset()</function>
1782 or <function>nmem_destroy()</function> will release all memory allocated
1783 on the handle since it was created (or since the last call to
1784 <function>nmem_reset()</function>. The function
1785 <function>nmem_total()</function> returns the number of bytes currently
1786 allocated on the handle.
1790 The nibble memory pool is shared amongst threads. POSIX
1791 mutex'es and WIN32 Critical sections are introduced to keep the
1792 module thread safe. Function <function>nmem_init()</function>
1793 initializes the nibble memory library and it is called automatically
1794 the first time the <literal>YAZ.DLL</literal> is loaded. &yaz; uses
1795 function <function>DllMain</function> to achieve this. You should
1796 <emphasis>not</emphasis> call <function>nmem_init</function> or
1797 <function>nmem_exit</function> unless you're absolute sure what
1798 you're doing. Note that in previous &yaz; versions you'd have to call
1799 <function>nmem_init</function> yourself.
1804 <sect1 id="tools.log"><title>Log</title>
1806 &yaz; has evolved a fairly complex log system which should be useful both
1807 for debugging &yaz; itself, debugging applications that use &yaz;, and for
1808 production use of those applications.
1811 The log functions are declared in header <filename>yaz/log.h</filename>
1812 and implemented in <filename>src/log.c</filename>.
1813 Due to name clash with syslog and some math utilities the logging
1814 interface has been modified as of YAZ 2.0.29. The obsolete interface
1815 is still available if in header file <filename>yaz/log.h</filename>.
1816 The key points of the interface are:
1819 void yaz_log(int level, const char *fmt, ...)
1821 void yaz_log_init(int level, const char *prefix, const char *name);
1822 void yaz_log_init_file(const char *fname);
1823 void yaz_log_init_level(int level);
1824 void yaz_log_init_prefix(const char *prefix);
1825 void yaz_log_time_format(const char *fmt);
1826 void yaz_log_init_max_size(int mx);
1828 int yaz_log_mask_str(const char *str);
1829 int yaz_log_module_level(const char *name);
1833 The reason for the whole log module is the <function>yaz_log</function>
1834 function. It takes a bitmask indicating the log levels, a
1835 <literal>printf</literal>-like format string, and a variable number of
1840 The <literal>log level</literal> is a bit mask, that says on which level(s)
1841 the log entry should be made, and optionally set some behaviour of the
1842 logging. In the most simple cases, it can be one of <literal>YLOG_FATAL,
1843 YLOG_DEBUG, YLOG_WARN, YLOG_LOG</literal>. Those can be combined with bits
1844 that modify the way the log entry is written:<literal>YLOG_ERRNO,
1845 YLOG_NOTIME, YLOG_FLUSH</literal>.
1846 Most of the rest of the bits are deprecated, and should not be used. Use
1847 the dynamic log levels instead.
1851 Applications that use &yaz;, should not use the LOG_LOG for ordinary
1852 messages, but should make use of the dynamic loglevel system. This consists
1853 of two parts, defining the loglevel and checking it.
1857 To define the log levels, the (main) program should pass a string to
1858 <function>yaz_log_mask_str</function> to define which log levels are to be
1859 logged. This string should be a comma-separated list of log level names,
1860 and can contain both hard-coded names and dynamic ones. The log level
1861 calculation starts with <literal>YLOG_DEFAULT_LEVEL</literal> and adds a bit
1862 for each word it meets, unless the word starts with a '-', in which case it
1863 clears the bit. If the string <literal>'none'</literal> is found,
1864 all bits are cleared. Typically this string comes from the command-line,
1865 often identified by <literal>-v</literal>. The
1866 <function>yaz_log_mask_str</function> returns a log level that should be
1867 passed to <function>yaz_log_init_level</function> for it to take effect.
1871 Each module should check what log bits it should be used, by calling
1872 <function>yaz_log_module_level</function> with a suitable name for the
1873 module. The name is cleared from a preceding path and an extension, if any,
1874 so it is quite possible to use <literal>__FILE__</literal> for it. If the
1875 name has been passed to <function>yaz_log_mask_str</function>, the routine
1876 returns a non-zero bitmask, which should then be used in consequent calls
1877 to yaz_log. (It can also be tested, so as to avoid unnecessary calls to
1878 yaz_log, in time-critical places, or when the log entry would take time
1883 Yaz uses the following dynamic log levels:
1884 <literal>server, session, request, requestdetail</literal> for the server
1886 <literal>zoom</literal> for the zoom client api.
1887 <literal>ztest</literal> for the simple test server.
1888 <literal>malloc, nmem, odr, eventl</literal> for internal debugging of yaz itself.
1889 Of course, any program using yaz is welcome to define as many new ones, as
1894 By default the log is written to stderr, but this can be changed by a call
1895 to <function>yaz_log_init_file</function> or
1896 <function>yaz_log_init</function>. If the log is directed to a file, the
1897 file size is checked at every write, and if it exceeds the limit given in
1898 <function>yaz_log_init_max_size</function>, the log is rotated. The
1899 rotation keeps one old version (with a <literal>.1</literal> appended to
1900 the name). The size defaults to 1GB. Setting it to zero will disable the
1905 A typical yaz-log looks like this
1906 13:23:14-23/11 yaz-ztest(1) [session] Starting session from tcp:127.0.0.1 (pid=30968)
1907 13:23:14-23/11 yaz-ztest(1) [request] Init from 'YAZ' (81) (ver 2.0.28) OK
1908 13:23:17-23/11 yaz-ztest(1) [request] Search Z: @attrset Bib-1 foo OK:7 hits
1909 13:23:22-23/11 yaz-ztest(1) [request] Present: [1] 2+2 OK 2 records returned
1910 13:24:13-23/11 yaz-ztest(1) [request] Close OK
1914 The log entries start with a time stamp. This can be omitted by setting the
1915 <literal>YLOG_NOTIME</literal> bit in the loglevel. This way automatic tests
1916 can be hoped to produce identical log files, that are easy to diff. The
1917 format of the time stamp can be set with
1918 <function>yaz_log_time_format</function>, which takes a format string just
1919 like <function>strftime</function>.
1923 Next in a log line comes the prefix, often the name of the program. For
1924 yaz-based servers, it can also contain the session number. Then
1925 comes one or more logbits in square brackets, depending on the logging
1926 level set by <function>yaz_log_init_level</function> and the loglevel
1927 passed to <function>yaz_log_init_level</function>. Finally comes the format
1928 string and additional values passed to <function>yaz_log</function>
1932 The log level <literal>YLOG_LOGLVL</literal>, enabled by the string
1933 <literal>loglevel</literal>, will log all the log-level affecting
1934 operations. This can come in handy if you need to know what other log
1935 levels would be useful. Grep the logfile for <literal>[loglevel]</literal>.
1939 The log system is almost independent of the rest of &yaz;, the only
1940 important dependence is of <filename>nmem</filename>, and that only for
1941 using the semaphore definition there.
1945 The dynamic log levels and log rotation were introduced in &yaz; 2.0.28. At
1946 the same time, the log bit names were changed from
1947 <literal>LOG_something</literal> to <literal>YLOG_something</literal>,
1948 to avoid collision with <filename>syslog.h</filename>.
1953 <sect1 id="tools.marc"><title>MARC</title>
1956 YAZ provides a fast utility that decodes MARC records and
1957 encodes to a varity of output formats. The MARC records must
1958 be encoded in ISO2709.
1961 #include <yaz/marcdisp.h>
1963 /* create handler */
1964 yaz_marc_t yaz_marc_create(void);
1966 void yaz_marc_destroy(yaz_marc_t mt);
1968 /* set XML mode YAZ_MARC_LINE, YAZ_MARC_SIMPLEXML, ... */
1969 void yaz_marc_xml(yaz_marc_t mt, int xmlmode);
1970 #define YAZ_MARC_LINE 0
1971 #define YAZ_MARC_SIMPLEXML 1
1972 #define YAZ_MARC_OAIMARC 2
1973 #define YAZ_MARC_MARCXML 3
1974 #define YAZ_MARC_ISO2709 4
1975 #define YAZ_MARC_XCHANGE 5
1977 /* supply iconv handle for character set conversion .. */
1978 void yaz_marc_iconv(yaz_marc_t mt, yaz_iconv_t cd);
1980 /* set debug level, 0=none, 1=more, 2=even more, .. */
1981 void yaz_marc_debug(yaz_marc_t mt, int level);
1983 /* decode MARC in buf of size bsize. Returns >0 on success; <=0 on failure.
1984 On success, result in *result with size *rsize. */
1985 int yaz_marc_decode_buf (yaz_marc_t mt, const char *buf, int bsize,
1986 char **result, int *rsize);
1988 /* decode MARC in buf of size bsize. Returns >0 on success; <=0 on failure.
1989 On success, result in WRBUF */
1990 int yaz_marc_decode_wrbuf (yaz_marc_t mt, const char *buf,
1991 int bsize, WRBUF wrbuf);
1995 A MARC conversion handle must be created by using
1996 <function>yaz_marc_create</function> and destroyed
1997 by calling <function>yaz_marc_destroy</function>.
2000 All other function operate on a <literal>yaz_marc_t</literal> handle.
2001 The output is specified by a call to <function>yaz_marc_xml</function>.
2002 The <literal>xmlmode</literal> must be one of
2005 <term>YAZ_MARC_LINE</term>
2008 A simple line-by-line format suitable for display but not
2009 recommend for further (machine) processing.
2015 <term>YAZ_MARC_MARXML</term>
2018 The resulting record is converted to MARCXML.
2024 <term>YAZ_MARC_ISO2709</term>
2027 The resulting record is converted to ISO2709 (MARC).
2034 The actual conversion functions are
2035 <function>yaz_marc_decode_buf</function> and
2036 <function>yaz_marc_decode_wrbuf</function> which decodes and encodes
2037 a MARC record. The former function operates on simple buffers, the
2038 stores the resulting record in a WRBUF handle (WRBUF is a simple string
2042 <title>Display of MARC record</title>
2044 The followint program snippet illustrates how the MARC API may
2045 be used to convert a MARC record to the line-by-line format:
2046 <programlisting><![CDATA[
2047 void print_marc(const char *marc_buf, int marc_buf_size)
2049 char *result; /* for result buf */
2050 int result_len; /* for size of result */
2051 yaz_marc_t mt = yaz_marc_create();
2052 yaz_marc_xml(mt, YAZ_MARC_LINE);
2053 yaz_marc_decode_buf(mt, marc_buf, marc_buf_size,
2054 &result, &result_len);
2055 fwrite(result, result_len, 1, stdout);
2056 yaz_marc_destroy(mt); /* note that result is now freed... */
2066 <!-- Keep this comment at the end of the file
2071 sgml-minimize-attributes:nil
2072 sgml-always-quote-attributes:t
2075 sgml-parent-document: "yaz.xml"
2076 sgml-local-catalogs: nil
2077 sgml-namecase-general:t