/usr/share/doc/yaz-doc/tools.html

<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 7. Supporting Tools</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="YAZ User's Guide and Reference"><link rel="up" href="index.html" title="YAZ User's Guide and Reference"><link rel="prev" href="soap.srw.html" title="4. SRU"><link rel="next" href="tools.oid.html" title="2. Object Identifiers"></head><body><link rel="stylesheet" type="text/css" href="common/style1.css"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 7. Supporting Tools</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="soap.srw.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="tools.oid.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="tools"></a>Chapter 7. Supporting Tools</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="sect1"><a href="tools.html#tools.query">1. Query Syntax Parsers</a></span></dt><dd><dl><dt><span class="sect2"><a href="tools.html#PQF">1.1. Prefix Query Format</a></span></dt><dd><dl><dt><span class="sect3"><a href="tools.html#PQF-prox">1.1.1. Using Proximity Operators with PQF</a></span></dt><dt><span class="sect3"><a href="tools.html#pqf-examples">1.1.2. PQF queries</a></span></dt></dl></dd><dt><span class="sect2"><a href="tools.html#CCL">1.2. CCL</a></span></dt><dd><dl><dt><span class="sect3"><a href="tools.html#ccl.syntax">1.2.1. CCL Syntax</a></span></dt><dt><span class="sect3"><a href="tools.html#ccl.qualifiers">1.2.2. CCL Qualifiers</a></span></dt><dt><span class="sect3"><a href="tools.html#ccl.api">1.2.3. CCL API</a></span></dt></dl></dd><dt><span class="sect2"><a href="tools.html#cql">1.3. CQL</a></span></dt><dd><dl><dt><span class="sect3"><a href="tools.html#cql.parsing">1.3.1. CQL parsing</a></span></dt><dt><span class="sect3"><a href="tools.html#cql.tree">1.3.2. CQL tree</a></span></dt><dt><span class="sect3"><a href="tools.html#cql.to.pqf">1.3.3. CQL to PQF conversion</a></span></dt><dt><span class="sect3"><a href="tools.html#cql.to.rpn">1.3.4. Specification of CQL to RPN mappings</a></span></dt><dt><span class="sect3"><a href="tools.html#cql.xcql">1.3.5. CQL to XCQL conversion</a></span></dt></dl></dd></dl></dd><dt><span class="sect1"><a href="tools.oid.html">2. Object Identifiers</a></span></dt><dd><dl><dt><span class="sect2"><a href="tools.oid.html#tools.oid.database">2.1. OID database</a></span></dt><dt><span class="sect2"><a href="tools.oid.html#tools.oid.std">2.2. Standard OIDs</a></span></dt></dl></dd><dt><span class="sect1"><a href="tools.nmem.html">3. Nibble Memory</a></span></dt><dt><span class="sect1"><a href="tools.log.html">4. Log</a></span></dt><dt><span class="sect1"><a href="marc.html">5. MARC</a></span></dt><dd><dl><dt><span class="sect2"><a href="marc.html#tools.turbomarc">5.1. TurboMARC</a></span></dt></dl></dd><dt><span class="sect1"><a href="tools.retrieval.html">6. Retrieval Facility</a></span></dt><dd><dl><dt><span class="sect2"><a href="tools.retrieval.html#tools.retrieval.format">6.1. Retrieval XML format</a></span></dt><dt><span class="sect2"><a href="tools.retrieval.html#tools.retrieval.examples">6.2. Retrieval Facility Examples</a></span></dt><dt><span class="sect2"><a href="tools.retrieval.html#tools.retrieval.api">6.3. API</a></span></dt></dl></dd></dl></div><p>
   In support of the service API - primarily the ASN module, which
   provides the pro-grammatic interface to the Z39.50 APDUs, YAZ contains
   a collection of tools that support the development of applications.
  </p><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="tools.query"></a>1. Query Syntax Parsers</h2></div></div></div><p>
    Since the type-1 (RPN) query structure has no direct, useful string
    representation, every origin application needs to provide some form of
    mapping from a local query notation or representation to a
    <span class="token">Z_RPNQuery</span> structure. Some programmers will prefer to
    construct the query manually, perhaps using
    <code class="function">odr_malloc()</code> to simplify memory management.
    The YAZ distribution includes three separate, query-generating tools
    that may be of use to you.
   </p><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="PQF"></a>1.1. Prefix Query Format</h3></div></div></div><p>
     Since RPN or reverse polish notation is really just a fancy way of
     describing a suffix notation format (operator follows operands), it
     would seem that the confusion is total when we now introduce a prefix
     notation for RPN. The reason is one of simple laziness - it's somewhat
     simpler to interpret a prefix format, and this utility was designed
     for maximum simplicity, to provide a baseline representation for use
     in simple test applications and scripting environments (like Tcl). The
     demonstration client included with YAZ uses the PQF.
    </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
      The PQF have been adopted by other parties developing Z39.50
      software. It is often referred to as Prefix Query Notation
      - PQN.
     </p></div><p>
     The PQF is defined by the pquery module in the YAZ library. 
     There are two sets of function that have similar behavior. First
     set operates on a PQF parser handle, second set doesn't. First set
     set of functions are more flexible than the second set. Second set
     is obsolete and is only provided to ensure backwards compatibility.
    </p><p>
     First set of functions all operate on a PQF parser handle:
    </p><pre class="synopsis">
     #include &lt;yaz/pquery.h&gt;

     YAZ_PQF_Parser yaz_pqf_create (void);

     void yaz_pqf_destroy (YAZ_PQF_Parser p);

     Z_RPNQuery *yaz_pqf_parse (YAZ_PQF_Parser p, ODR o, const char *qbuf);

     Z_AttributesPlusTerm *yaz_pqf_scan (YAZ_PQF_Parser p, ODR o,
                          Odr_oid **attributeSetId, const char *qbuf);


     int yaz_pqf_error (YAZ_PQF_Parser p, const char **msg, size_t *off);
    </pre><p>
     A PQF parser is created and destructed by functions
     <code class="function">yaz_pqf_create</code> and
     <code class="function">yaz_pqf_destroy</code> respectively.
     Function <code class="function">yaz_pqf_parse</code> parses query given
     by string <code class="literal">qbuf</code>. If parsing was successful,
     a Z39.50 RPN Query is returned which is created using ODR stream
     <code class="literal">o</code>. If parsing failed, a NULL pointer is
     returned.
     Function <code class="function">yaz_pqf_scan</code> takes a scan query in 
     <code class="literal">qbuf</code>. If parsing was successful, the function
     returns attributes plus term pointer and modifies
     <code class="literal">attributeSetId</code> to hold attribute set for the
     scan request - both allocated using ODR stream <code class="literal">o</code>.
     If parsing failed, yaz_pqf_scan returns a NULL pointer.
     Error information for bad queries can be obtained by a call to
     <code class="function">yaz_pqf_error</code> which returns an error code and
     modifies <code class="literal">*msg</code> to point to an error description,
     and modifies <code class="literal">*off</code> to the offset within last
     query were parsing failed.
    </p><p>
     The second set of functions are declared as follows:
    </p><pre class="synopsis">
     #include &lt;yaz/pquery.h&gt;

     Z_RPNQuery *p_query_rpn (ODR o, oid_proto proto, const char *qbuf);

     Z_AttributesPlusTerm *p_query_scan (ODR o, oid_proto proto,
                             Odr_oid **attributeSetP, const char *qbuf);

     int p_query_attset (const char *arg);
    </pre><p>
     The function <code class="function">p_query_rpn()</code> takes as arguments an
      <acronym class="acronym">ODR</acronym> stream (see section <a class="link" href="odr.html" title="Chapter 8. The ODR Module">The ODR Module</a>)
     to provide a memory source (the structure created is released on
     the next call to <code class="function">odr_reset()</code> on the stream), a
     protocol identifier (one of the constants <span class="token">PROTO_Z3950</span> and
     <span class="token">PROTO_SR</span>), an attribute set reference, and
     finally a null-terminated string holding the query string.
    </p><p>
     If the parse went well, <code class="function">p_query_rpn()</code> returns a
     pointer to a <code class="literal">Z_RPNQuery</code> structure which can be
     placed directly into a <code class="literal">Z_SearchRequest</code>. 
     If parsing failed, due to syntax error, a NULL pointer is returned.
    </p><p>
     The <code class="literal">p_query_attset</code> specifies which attribute set
     to use if the query doesn't specify one by the
     <code class="literal">@attrset</code> operator.
     The <code class="literal">p_query_attset</code> returns 0 if the argument is a
     valid attribute set specifier; otherwise the function returns -1.
    </p><p>
     The grammar of the PQF is as follows:
    </p><div class="literallayout"><p><br>
     query ::= top-set query-struct.<br>
<br>
     top-set ::= [ '@attrset' string ]<br>
<br>
     query-struct ::= attr-spec | simple | complex | '@term' term-type query<br>
<br>
     attr-spec ::= '@attr' [ string ] string query-struct<br>
<br>
     complex ::= operator query-struct query-struct.<br>
<br>
     operator ::= '@and' | '@or' | '@not' | '@prox' proximity.<br>
<br>
     simple ::= result-set | term.<br>
<br>
     result-set ::= '@set' string.<br>
<br>
     term ::= string.<br>
<br>
     proximity ::= exclusion distance ordered relation which-code unit-code.<br>
<br>
     exclusion ::= '1' | '0' | 'void'.<br>
<br>
     distance ::= integer.<br>
<br>
     ordered ::= '1' | '0'.<br>
<br>
     relation ::= integer.<br>
<br>
     which-code ::= 'known' | 'private' | integer.<br>
<br>
     unit-code ::= integer.<br>
<br>
     term-type ::= 'general' | 'numeric' | 'string' | 'oid' | 'datetime' | 'null'.<br>
    </p></div><p>
     You will note that the syntax above is a fairly faithful
     representation of RPN, except for the Attribute, which has been
     moved a step away from the term, allowing you to associate one or more
     attributes with an entire query structure. The parser will
     automatically apply the given attributes to each term as required.
    </p><p>
     The @attr operator is followed by an attribute specification 
     (<code class="literal">attr-spec</code> above). The specification consists
     of an optional attribute set, an attribute type-value pair and
     a sub-query. The attribute type-value pair is packed in one string:
     an attribute type, an equals sign, and an attribute value, like this:
     <code class="literal">@attr 1=1003</code>.
     The type is always an integer but the value may be either an
     integer or a string (if it doesn't start with a digit character).
     A string attribute-value is encoded as a Type-1 ``complex''
     attribute with the list of values containing the single string
     specified, and including no semantic indicators.
    </p><p>
     Version 3 of the Z39.50 specification defines various encoding of terms.
     Use <code class="literal">@term </code> <em class="replaceable"><code>type</code></em>
     <em class="replaceable"><code>string</code></em>,
     where type is one of: <code class="literal">general</code>,
     <code class="literal">numeric</code> or <code class="literal">string</code>
     (for InternationalString).
     If no term type has been given, the <code class="literal">general</code> form
     is used.  This is the only encoding allowed in both versions 2 and 3
     of the Z39.50 standard.
    </p><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="PQF-prox"></a>1.1.1. Using Proximity Operators with PQF</h4></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
	  This is an advanced topic, describing how to construct
	  queries that make very specific requirements on the
	  relative location of their operands.
	  You may wish to skip this section and go straight to
	  <a class="link" href="tools.html#pqf-examples" title="1.1.2. PQF queries">the example PQF queries</a>.
	</p><p>
	  </p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>
	      Most Z39.50 servers do not support proximity searching, or
	      support only a small subset of the full functionality that
	      can be expressed using the PQF proximity operator.  Be
	      aware that the ability to <span class="emphasis"><em>express</em></span> a
	      query in PQF is no guarantee that any given server will
	      be able to <span class="emphasis"><em>execute</em></span> it.
	    </p></div><p>
	</p></div><p>
        The proximity operator <code class="literal">@prox</code> is a special
        and more restrictive version of the conjunction operator
        <code class="literal">@and</code>.  Its semantics are described in 
	section 3.7.2 (Proximity) of Z39.50 the standard itself, which
        can be read on-line at
	<a class="ulink" href="http://www.loc.gov/z3950/agency/markup/09.html#3.7.2" target="_top">http://www.loc.gov/z3950/agency/markup/09.html#3.7.2</a>
      </p><p>
	In PQF, the proximity operation is represented by a sequence
	of the form
	</p><pre class="screen">
@prox <em class="replaceable"><code>exclusion</code></em> <em class="replaceable"><code>distance</code></em> <em class="replaceable"><code>ordered</code></em> <em class="replaceable"><code>relation</code></em> <em class="replaceable"><code>which-code</code></em> <em class="replaceable"><code>unit-code</code></em>
	</pre><p>
	in which the meanings of the parameters are as described in in
	the standard, and they can take the following values:
	</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><b>exclusion. </b>
	    0 = false (i.e. the proximity condition specified by the
	    remaining parameters must be satisfied) or
	    1 = true (the proximity condition specified by the
	    remaining parameters must <span class="emphasis"><em>not</em></span> be
	    satisifed).
	  </p></li><li class="listitem"><p><b>distance. </b>
	    An integer specifying the difference between the locations
	    of the operands: e.g. two adjacent words would have
	    distance=1 since their locations differ by one unit.
	  </p></li><li class="listitem"><p><b>ordered. </b>
	    1 = ordered (the operands must occur in the order the
	    query specifies them) or
	    0 = unordered (they may appear in either order).
	  </p></li><li class="listitem"><p><b>relation. </b>
	    Recognised values are
	    1 (lessThan),
	    2 (lessThanOrEqual),
	    3 (equal),
	    4 (greaterThanOrEqual),
	    5 (greaterThan) and
	    6 (notEqual).
	  </p></li><li class="listitem"><p><b>which-code. </b>
	    <code class="literal">known</code>
	    or
	    <code class="literal">k</code>
	    (the unit-code parameter is taken from the well-known list
	    of alternatives described in below) or
	    <code class="literal">private</code>
	    or
	    <code class="literal">p</code>
	    (the unit-code paramater has semantics specific to an
	    out-of-band agreement such as a profile).
	  </p></li><li class="listitem"><p><b>unit-code. </b>
	    If the which-code parameter is <code class="literal">known</code>
	    then the recognised values are
	    1 (character),
	    2 (word),
	    3 (sentence),
	    4 (paragraph),
	    5 (section),
	    6 (chapter),
	    7 (document),
	    8 (element),
	    9 (subelement),
	    10 (elementType) and
	    11 (byte).
	    If which-code is <code class="literal">private</code> then the
	    acceptable values are determined by the profile.
	  </p></li></ul></div><p>
	(The numeric values of the relation and well-known unit-code
	parameters are taken straight from
	<a class="ulink" href="http://www.loc.gov/z3950/agency/asn1.html#ProximityOperator" target="_top">the ASN.1</a> of the proximity structure in the standard.)
      </p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="pqf-examples"></a>1.1.2. PQF queries</h4></div></div></div><div class="example"><a name="example.pqf.simple.terms"></a><p class="title"><b>Example 7.1. PQF queries using simple terms</b></p><div class="example-contents"><p>
       </p><pre class="screen">
	dylan

	"bob dylan"
       </pre><p>
      </p></div></div><br class="example-break"><div class="example"><a name="pqf.example.pqf.boolean.operators"></a><p class="title"><b>Example 7.2. PQF boolean operators</b></p><div class="example-contents"><p>
       </p><pre class="screen">
	@or "dylan" "zimmerman"

	@and @or dylan zimmerman when

	@and when @or dylan zimmerman
       </pre><p>
      </p></div></div><br class="example-break"><div class="example"><a name="example.pqf.result.sets"></a><p class="title"><b>Example 7.3. PQF references to result sets</b></p><div class="example-contents"><p>
       </p><pre class="screen">
	@set Result-1

	@and @set seta @set setb
       </pre><p>
      </p></div></div><br class="example-break"><div class="example"><a name="example.pqf.attributes"></a><p class="title"><b>Example 7.4. Attributes for terms</b></p><div class="example-contents"><p>
       </p><pre class="screen">
	@attr 1=4 computer

	@attr 1=4 @attr 4=1 "self portrait"

	@attrset exp1 @attr 1=1 CategoryList

	@attr gils 1=2008 Copenhagen

	@attr 1=/book/title computer
       </pre><p>
      </p></div></div><br class="example-break"><div class="example"><a name="example.pqf.proximity"></a><p class="title"><b>Example 7.5. PQF Proximity queries</b></p><div class="example-contents"><p>
       </p><pre class="screen">
	@prox 0 3 1 2 k 2 dylan zimmerman
       </pre><p>
       </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
	 Here the parameters 0, 3, 1, 2, k and 2 represent exclusion,
	 distance, ordered, relation, which-code and unit-code, in that
	 order.  So:
	 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
	    exclusion = 0: the proximity condition must hold
	   </p></li><li class="listitem"><p>
	    distance = 3: the terms must be three units apart
	   </p></li><li class="listitem"><p>
	    ordered = 1: they must occur in the order they are specified
	   </p></li><li class="listitem"><p>
	    relation = 2: lessThanOrEqual (to the distance of 3 units)
	   </p></li><li class="listitem"><p>
	    which-code is ``known'', so the standard unit-codes are used
	   </p></li><li class="listitem"><p>
	    unit-code = 2: word.
	   </p></li></ul></div><p>
	 So the whole proximity query means that the words
	 <code class="literal">dylan</code> and <code class="literal">zimmerman</code> must
	 both occur in the record, in that order, differing in position
	 by three or fewer words (i.e. with two or fewer words between
	 them.)  The query would find ``Bob Dylan, aka. Robert
	 Zimmerman'', but not ``Bob Dylan, born as Robert Zimmerman''
	 since the distance in this case is four.
	</p></div><p>
      </p></div></div><br class="example-break"><div class="example"><a name="example.pqf.search.term.type"></a><p class="title"><b>Example 7.6. PQF specification of search term type</b></p><div class="example-contents"><p>
       </p><pre class="screen">
	@term string "a UTF-8 string, maybe?"
       </pre><p>
      </p></div></div><br class="example-break"><div class="example"><a name="example.pqf.mixed.queries"></a><p class="title"><b>Example 7.7. PQF mixed queries</b></p><div class="example-contents"><p>
       </p><pre class="screen">
	@or @and bob dylan @set Result-1
	
	@attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming"
	
	@and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109
      </pre><p>
       </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
	 The last of these examples is a spatial search: in
	 <a class="ulink" href="http://www.gils.net/prof_v2.html#sec_7_4" target="_top">the GILS attribute set</a>,
	 access point
	 2038 indicates West Bounding Coordinate and
	 2030 indicates East Bounding Coordinate,
	 so the query is for areas extending from -114 degrees
	 to no more than -109 degrees.
	</p></div><p>
      </p></div></div><br class="example-break"></div></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="CCL"></a>1.2. CCL</h3></div></div></div><p>
     Not all users enjoy typing in prefix query structures and numerical
     attribute values, even in a minimalistic test client. In the library
     world, the more intuitive Common Command Language - CCL (ISO 8777)
     has enjoyed some popularity - especially before the widespread
     availability of graphical interfaces. It is still useful in
     applications where you for some reason or other need to provide a
     symbolic language for expressing boolean query structures.
    </p><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="ccl.syntax"></a>1.2.1. CCL Syntax</h4></div></div></div><p>
      The CCL parser obeys the following grammar for the FIND argument.
      The syntax is annotated by in the lines prefixed by
      <code class="literal">--</code>.
     </p><pre class="screen">
      CCL-Find ::= CCL-Find Op Elements
                | Elements.

      Op ::= "and" | "or" | "not"
      -- The above means that Elements are separated by boolean operators.

      Elements ::= '(' CCL-Find ')'
                | Set
                | Terms
                | Qualifiers Relation Terms
                | Qualifiers Relation '(' CCL-Find ')'
                | Qualifiers '=' string '-' string
      -- Elements is either a recursive definition, a result set reference, a
      -- list of terms, qualifiers followed by terms, qualifiers followed
      -- by a recursive definition or qualifiers in a range (lower - upper).

      Set ::= 'set' = string
      -- Reference to a result set

      Terms ::= Terms Prox Term
             | Term
      -- Proximity of terms.

      Term ::= Term string
            | string
      -- This basically means that a term may include a blank

      Qualifiers ::= Qualifiers ',' string
                  | string
      -- Qualifiers is a list of strings separated by comma

      Relation ::= '=' | '&gt;=' | '&lt;=' | '&lt;&gt;' | '&gt;' | '&lt;'
      -- Relational operators. This really doesn't follow the ISO8777
      -- standard.

      Prox ::= '%' | '!'
      -- Proximity operator

     </pre><div class="example"><a name="example.ccl.queries"></a><p class="title"><b>Example 7.8. CCL queries</b></p><div class="example-contents"><p>
       The following queries are all valid:
      </p><pre class="screen">
       dylan
       
       "bob dylan"
       
       dylan or zimmerman
       
       set=1
       
       (dylan and bob) or set=1
       
      </pre><p>
       Assuming that the qualifiers <code class="literal">ti</code>,
       <code class="literal">au</code>
       and <code class="literal">date</code> are defined we may use:
      </p><pre class="screen">
       ti=self portrait
       
       au=(bob dylan and slow train coming)

       date&gt;1980 and (ti=((self portrait)))
       
      </pre></div></div><br class="example-break"></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="ccl.qualifiers"></a>1.2.2. CCL Qualifiers</h4></div></div></div><p>
      Qualifiers are used to direct the search to a particular searchable
      index, such as title (ti) and author indexes (au). The CCL standard
      itself doesn't specify a particular set of qualifiers, but it does
      suggest a few short-hand notations. You can customize the CCL parser
      to support a particular set of qualifiers to reflect the current target
      profile. Traditionally, a qualifier would map to a particular
      use-attribute within the BIB-1 attribute set. It is also
      possible to set other attributes, such as the structure
      attribute.
     </p><p>
      A  CCL profile is a set of predefined CCL qualifiers that may be
      read from a file or set in the CCL API.
      The YAZ client reads its CCL qualifiers from a file named
      <code class="filename">default.bib</code>. There are four types of
      lines in a CCL profile: qualifier specification,
      qualifier alias, comments and directives.
     </p><div class="sect4"><div class="titlepage"><div><div><h5 class="title"><a name="ccl.qualifier.specification"></a>1.2.2.1. Qualifier specification</h5></div></div></div><p>
       A qualifier specification is of the form:
      </p><p>
       <em class="replaceable"><code>qualifier-name</code></em>  
       [<em class="replaceable"><code>attributeset</code></em><code class="literal">,</code>]<em class="replaceable"><code>type</code></em><code class="literal">=</code><em class="replaceable"><code>val</code></em>
       [<em class="replaceable"><code>attributeset</code></em><code class="literal">,</code>]<em class="replaceable"><code>type</code></em><code class="literal">=</code><em class="replaceable"><code>val</code></em> ...      
      </p><p>
       where <em class="replaceable"><code>qualifier-name</code></em> is the name of the
       qualifier to be used (eg. <code class="literal">ti</code>),
       <em class="replaceable"><code>type</code></em> is attribute type in the attribute
       set (Bib-1 is used if no attribute set is given) and
       <em class="replaceable"><code>val</code></em> is attribute value.
       The <em class="replaceable"><code>type</code></em> can be specified as an
       integer or as it be specified either as a single-letter:
       <code class="literal">u</code> for use, 
       <code class="literal">r</code> for relation,<code class="literal">p</code> for position,
       <code class="literal">s</code> for structure,<code class="literal">t</code> for truncation
       or <code class="literal">c</code> for completeness.
       The attributes for the special qualifier name <code class="literal">term</code>
       are used when no CCL qualifier is given in a query.
       </p><div class="table"><a name="ccl.common.bib1.attributes"></a><p class="title"><b>Table 7.1. Common Bib-1 attributes</b></p><div class="table-contents"><table summary="Common Bib-1 attributes" border="1"><colgroup><col class="type"><col class="description"></colgroup><thead><tr><th>Type</th><th>Description</th></tr></thead><tbody><tr><td><code class="literal">u=</code><em class="replaceable"><code>value</code></em></td><td>
	    Use attribute (1). Common use attributes are
	    1 Personal-name, 4 Title, 7 ISBN, 8 ISSN, 30 Date,
	    62 Subject, 1003 Author), 1016 Any. Specify value
	    as an integer.
	   </td></tr><tr><td><code class="literal">r=</code><em class="replaceable"><code>value</code></em></td><td>
	    Relation attribute (2). Common values are
	    1 &lt;, 2 &lt;=, 3 =, 4 &gt;=, 5 &gt;, 6 &lt;&gt;,
	    100 phonetic, 101 stem, 102 relevance, 103 always matches.
	   </td></tr><tr><td><code class="literal">p=</code><em class="replaceable"><code>value</code></em></td><td>
	    Position attribute (3). Values: 1 first in field, 2
	    first in any subfield, 3 any position in field.
	   </td></tr><tr><td><code class="literal">s=</code><em class="replaceable"><code>value</code></em></td><td>
	    Structure attribute (4). Values: 1 phrase, 2 word,
	    3 key, 4 year, 5 date, 6 word list, 100 date (un),
	    101 name (norm), 102 name (un), 103 structure, 104 urx,
	    105 free-form-text, 106 document-text, 107 local-number,
	    108 string, 109 numeric string.
	   </td></tr><tr><td><code class="literal">t=</code><em class="replaceable"><code>value</code></em></td><td>
	    Truncation attribute (5). Values: 1 right, 2 left,
	    3 left&amp; right, 100 none, 101 process #, 102 regular-1,
	    103 regular-2, 104 CCL.
	   </td></tr><tr><td><code class="literal">c=</code><em class="replaceable"><code>value</code></em></td><td>
	    Completeness attribute (6). Values: 1 incomplete subfield,
	    2 complete subfield, 3 complete field.
	   </td></tr></tbody></table></div></div><p><br class="table-break">
      </p><p>
       Refer to <a class="xref" href="bib1.html" title="Bib-1 Attribute Set"><span class="refentrytitle">Bib-1 Attribute Set</span>(7)</a> or the complete
       <a class="ulink" href="http://www.loc.gov/z3950/agency/defns/bib1.html" target="_top">list of Bib-1 attributes</a>
      </p><p>
       It is also possible to specify non-numeric attribute values, 
       which are used in combination with certain types.
       The special combinations are:
       
       </p><div class="table"><a name="ccl.special.attribute.combos"></a><p class="title"><b>Table 7.2. Special attribute combos</b></p><div class="table-contents"><table summary="Special attribute combos" border="1"><colgroup><col class="name"><col class="description"></colgroup><thead><tr><th>Name</th><th>Description</th></tr></thead><tbody><tr><td><code class="literal">s=pw</code></td><td>
	    The structure is set to either word or phrase depending
	    on the number of tokens in a term (phrase-word).
	   </td></tr><tr><td><code class="literal">s=al</code></td><td>
	    Each token in the term is ANDed. (and-list).
	    This does not set the structure at all.
	   </td></tr><tr><td><code class="literal">s=ol</code></td><td>
	    Each token in the term is ORed. (or-list).
	    This does not set the structure at all.
	   </td></tr><tr><td><code class="literal">r=o</code></td><td>
	    Allows ranges and the operators greather-than, less-than, ...
	    equals.
	    This sets Bib-1 relation attribute accordingly (relation
	    ordered). A query construct is only treated as a range if
	    dash is used and that is surrounded by white-space. So
	    <code class="literal">-1980</code> is treated as term 
	    <code class="literal">"-1980"</code> not <code class="literal">&lt;= 1980</code>.
	    If <code class="literal">- 1980</code> is used, however, that is
	    treated as a range.
	   </td></tr><tr><td><code class="literal">r=r</code></td><td>
	    Similar to <code class="literal">r=o</code> but assumes that terms
	    are non-negative (not prefixed with <code class="literal">-</code>).
	    Thus, a dash will always be treated as a range.
	    The construct <code class="literal">1980-1990</code> is
	    treated as a range with <code class="literal">r=r</code> but as a
	    single term <code class="literal">"1980-1990"</code> with
	    <code class="literal">r=o</code>. The special attribute
	    <code class="literal">r=r</code> is available in YAZ 2.0.24 or later.
	   </td></tr><tr><td><code class="literal">t=l</code></td><td>
	    Allows term to be left-truncated.
	    If term is of the form <code class="literal">?x</code>, the resulting
	    Type-1 term is <code class="literal">x</code> and truncation is left.
	   </td></tr><tr><td><code class="literal">t=r</code></td><td>
	    Allows term to be right-truncated.
	    If term is of the form <code class="literal">x?</code>, the resulting
	    Type-1 term is <code class="literal">x</code> and truncation is right.
	   </td></tr><tr><td><code class="literal">t=n</code></td><td>
	    If term is does not include <code class="literal">?</code>, the
	    truncation attribute is set to none (100).
	   </td></tr><tr><td><code class="literal">t=b</code></td><td>
	    Allows term to be both left&amp;right truncated.
	    If term is of the form <code class="literal">?x?</code>, the
	    resulting term is <code class="literal">x</code> and trunctation is
	    set to both left&amp;right.
	   </td></tr><tr><td><code class="literal">t=x</code></td><td>
	    Allows masking anywhere in a term, thus fully supporting
	    # (mask one character) and ? (zero or more of any).
	    If masking is used, trunction is set to 102 (regexp-1 in term)
	    and the term is converted accordingly to a regular expression.
	   </td></tr><tr><td><code class="literal">t=z</code></td><td>
	    Allows masking anywhere in a term, thus fully supporting
	    # (mask one character) and ? (zero or more of any).
	    If masking is used, trunction is set to 104 (Z39.58 in term)
	    and the term is converted accordingly to Z39.58 masking term -
	    actually the same truncation as CCL itself.
	   </td></tr></tbody></table></div></div><p><br class="table-break">
      </p><div class="example"><a name="example.ccl.profile"></a><p class="title"><b>Example 7.9. CCL profile</b></p><div class="example-contents"><p>
	Consider the following definition:
       </p><pre class="screen">
	ti       u=4 s=1
	au       u=1 s=1
	term     s=105
	ranked   r=102
	date     u=30 r=o
      </pre><p>
	<code class="literal">ti</code> and <code class="literal">au</code> both set 
	structure attribute to phrase (s=1).
	<code class="literal">ti</code>
	sets the use-attribute to 4. <code class="literal">au</code> sets the
	use-attribute to 1.
	When no qualifiers are used in the query the structure-attribute is
	set to free-form-text (105) (rule for <code class="literal">term</code>).
	The <code class="literal">date</code> sets the relation attribute to
	the relation used in the CCL query and sets the use attribute
	to 30 (Bib-1 Date).
       </p><p>
	You can combine attributes. To Search for "ranked title" you
	can do 
	</p><pre class="screen">
	 ti,ranked=knuth computer
	</pre><p>
	which will set relation=ranked, use=title, structure=phrase.
       </p><p>
	Query
	</p><pre class="screen">
	 date &gt; 1980
	</pre><p>
	is a valid query. But
	</p><pre class="screen">
	 ti &gt; 1980
	</pre><p>
	is invalid.
       </p></div></div><br class="example-break"></div><div class="sect4"><div class="titlepage"><div><div><h5 class="title"><a name="ccl.qualifier.alias"></a>1.2.2.2. Qualifier alias</h5></div></div></div><p>
       A qualifier alias is of the form:
      </p><p>
       <em class="replaceable"><code>q</code></em>  
       <em class="replaceable"><code>q1</code></em> <em class="replaceable"><code>q2</code></em> ..
      </p><p>
       which declares <em class="replaceable"><code>q</code></em> to
       be an alias for <em class="replaceable"><code>q1</code></em>, 
       <em class="replaceable"><code>q2</code></em>... such that the CCL
       query <em class="replaceable"><code>q=x</code></em> is equivalent to
       <em class="replaceable"><code>q1=x or q2=x or ...</code></em>.
      </p></div><div class="sect4"><div class="titlepage"><div><div><h5 class="title"><a name="ccl.comments"></a>1.2.2.3. Comments</h5></div></div></div><p>
       Lines with white space or lines that begin with
       character <code class="literal">#</code> are treated as comments.
      </p></div><div class="sect4"><div class="titlepage"><div><div><h5 class="title"><a name="ccl.directives"></a>1.2.2.4. Directives</h5></div></div></div><p>
       Directive specifications takes the form
      </p><p><code class="literal">@</code><em class="replaceable"><code>directive</code></em> <em class="replaceable"><code>value</code></em>
      </p><div class="table"><a name="ccl.directives.table"></a><p class="title"><b>Table 7.3. CCL directives</b></p><div class="table-contents"><table summary="CCL directives" border="1"><colgroup><col class="name"><col class="description"><col class="default"></colgroup><thead><tr><th>Name</th><th>Description</th><th>Default</th></tr></thead><tbody><tr><td>truncation</td><td>Truncation character</td><td><code class="literal">?</code></td></tr><tr><td>field</td><td>Specifies how multiple fields are to be
	   combined. There are two modes: <code class="literal">or</code>:
	   multiple qualifier fields are ORed,
	   <code class="literal">merge</code>: attributes for the qualifier
	   fields are merged and assigned to one term.
	   </td><td><code class="literal">merge</code></td></tr><tr><td>case</td><td>Specificies if CCL operatores and qualifiers should be
	   compared with case sensitivity or not. Specify 0 for
	   case sensitive; 1 for case insensitive.</td><td><code class="literal">0</code></td></tr><tr><td>and</td><td>Specifies token for CCL operator AND.</td><td><code class="literal">and</code></td></tr><tr><td>or</td><td>Specifies token for CCL operator OR.</td><td><code class="literal">or</code></td></tr><tr><td>not</td><td>Specifies token for CCL operator NOT.</td><td><code class="literal">not</code></td></tr><tr><td>set</td><td>Specifies token for CCL operator SET.</td><td><code class="literal">set</code></td></tr></tbody></table></div></div><br class="table-break"></div></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="ccl.api"></a>1.2.3. CCL API</h4></div></div></div><p>
      All public definitions can be found in the header file
      <code class="filename">ccl.h</code>. A profile identifier is of type
      <code class="literal">CCL_bibset</code>. A profile must be created with the call
      to the function <code class="function">ccl_qual_mk</code> which returns a profile
      handle of type <code class="literal">CCL_bibset</code>.
     </p><p>
      To read a file containing qualifier definitions the function
      <code class="function">ccl_qual_file</code> may be convenient. This function
      takes an already opened <code class="literal">FILE</code> handle pointer as
      argument along with a <code class="literal">CCL_bibset</code> handle.
     </p><p>
      To parse a simple string with a FIND query use the function
     </p><pre class="screen">
struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str,
                                   int *error, int *pos);
     </pre><p>
      which takes the CCL profile (<code class="literal">bibset</code>) and query
      (<code class="literal">str</code>) as input. Upon successful completion the RPN
      tree is returned. If an error occur, such as a syntax error, the integer
      pointed to by <code class="literal">error</code> holds the error code and
      <code class="literal">pos</code> holds the offset inside query string in which
      the parsing failed.
     </p><p>
      An English representation of the error may be obtained by calling
      the <code class="literal">ccl_err_msg</code> function. The error codes are
      listed in <code class="filename">ccl.h</code>.
     </p><p>
      To convert the CCL RPN tree (type
      <code class="literal">struct ccl_rpn_node *</code>)
      to the Z_RPNQuery of YAZ the function <code class="function">ccl_rpn_query</code>
      must be used. This function which is part of YAZ is implemented in
      <code class="filename">yaz-ccl.c</code>.
      After calling this function the CCL RPN tree is probably no longer
      needed. The <code class="literal">ccl_rpn_delete</code> destroys the CCL RPN tree.
     </p><p>
      A CCL profile may be destroyed by calling the
      <code class="function">ccl_qual_rm</code> function.
     </p><p>
      The token names for the CCL operators may be changed by setting the
      globals (all type <code class="literal">char *</code>)
      <code class="literal">ccl_token_and</code>, <code class="literal">ccl_token_or</code>,
      <code class="literal">ccl_token_not</code> and <code class="literal">ccl_token_set</code>.
      An operator may have aliases, i.e. there may be more than one name for
      the operator. To do this, separate each alias with a space character.
     </p></div></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="cql"></a>1.3. CQL</h3></div></div></div><p>
     <a class="ulink" href="http://www.loc.gov/standards/sru/specs/cql.html" target="_top">CQL</a>
      - Common Query Language - was defined for the
     <a class="ulink" href="http://www.loc.gov/standards/sru/" target="_top">SRU</a> protocol.
     In many ways CQL has a similar syntax to CCL.
     The objective of CQL is different. Where CCL aims to be
     an end-user language, CQL is <span class="emphasis"><em>the</em></span> protocol
     query language for SRU.
    </p><div class="tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3><p>
      If you are new to CQL, read the 
      <a class="ulink" href="http://zing.z3950.org/cql/intro.html" target="_top">Gentle Introduction</a>.
     </p></div><p>
     The CQL parser in YAZ provides the following:
     </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
        It parses and validates a CQL query.
       </p></li><li class="listitem"><p>
        It generates a C structure that allows you to convert
        a CQL query to some other query language, such as SQL.
       </p></li><li class="listitem"><p>
        The parser converts a valid CQL query to PQF, thus providing a
        way to use CQL for both SRU servers and Z39.50 targets at the
        same time.
       </p></li><li class="listitem"><p>
        The parser converts CQL to
        <a class="ulink" href="http://www.loc.gov/standards/sru/xml-files/srw-types.xsd" target="_top">XCQL</a>.
        XCQL is an XML representation of CQL.
        XCQL is part of the SRU specification. However, since SRU
        supports CQL only, we don't expect XCQL to be widely used.
        Furthermore, CQL has the advantage over XCQL that it is
        easy to read.
       </p></li></ul></div><p>
    </p><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="cql.parsing"></a>1.3.1. CQL parsing</h4></div></div></div><p>
      A CQL parser is represented by the <code class="literal">CQL_parser</code>
      handle. Its contents should be considered YAZ internal (private).
      </p><pre class="synopsis">
#include &lt;yaz/cql.h&gt;

typedef struct cql_parser *CQL_parser;

CQL_parser cql_parser_create(void);
void cql_parser_destroy(CQL_parser cp);
      </pre><p>
     A parser is created by <code class="function">cql_parser_create</code> and
     is destroyed by <code class="function">cql_parser_destroy</code>.
     </p><p>
      To parse a CQL query string, the following function
      is provided:
      </p><pre class="synopsis">
int cql_parser_string(CQL_parser cp, const char *str);
      </pre><p>
      A CQL query is parsed by the <code class="function">cql_parser_string</code>
      which takes a query <em class="parameter"><code>str</code></em>.
      If the query was valid (no syntax errors), then zero is returned;
      otherwise -1 is returned to indicate a syntax error.
     </p><p>
      </p><pre class="synopsis">
int cql_parser_stream(CQL_parser cp,
                      int (*getbyte)(void *client_data),
                      void (*ungetbyte)(int b, void *client_data),
                      void *client_data);

int cql_parser_stdio(CQL_parser cp, FILE *f);
      </pre><p>
      The functions <code class="function">cql_parser_stream</code> and
      <code class="function">cql_parser_stdio</code> parses a CQL query
      - just like <code class="function">cql_parser_string</code>.
      The only difference is that the CQL query can be
      fed to the parser in different ways.
      The <code class="function">cql_parser_stream</code> uses a generic
      byte stream as input. The <code class="function">cql_parser_stdio</code>
      uses a <code class="literal">FILE</code> handle which is opened for reading.
     </p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="cql.tree"></a>1.3.2. CQL tree</h4></div></div></div><p>
      The the query string is valid, the CQL parser
      generates a tree representing the structure of the
      CQL query.
     </p><p>
      </p><pre class="synopsis">
struct cql_node *cql_parser_result(CQL_parser cp);
      </pre><p>
      <code class="function">cql_parser_result</code> returns the
      a pointer to the root node of the resulting tree.
     </p><p>
      Each node in a CQL tree is represented by a 
      <code class="literal">struct cql_node</code>.
      It is defined as follows:
      </p><pre class="synopsis">
#define CQL_NODE_ST 1
#define CQL_NODE_BOOL 2
struct cql_node {
    int which;
    union {
        struct {
            char *index;
	    char *index_uri;
            char *term;
            char *relation;
	    char *relation_uri;
            struct cql_node *modifiers;
        } st;
        struct {
            char *value;
            struct cql_node *left;
            struct cql_node *right;
            struct cql_node *modifiers;
        } boolean;
    } u;
};
      </pre><p>
      There are two node types: search term (ST) and boolean (BOOL).
      A modifier is treated as a search term too.
     </p><p>
      The search term node has five members:
      </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
         <code class="literal">index</code>: index for search term.
         If an index is unspecified for a search term,
         <code class="literal">index</code> will be NULL.
        </p></li><li class="listitem"><p>
         <code class="literal">index_uri</code>: index URi for search term
	 or NULL if none could be resolved for the index.
        </p></li><li class="listitem"><p>
         <code class="literal">term</code>: the search term itself.
        </p></li><li class="listitem"><p>
         <code class="literal">relation</code>: relation for search term.
        </p></li><li class="listitem"><p>
         <code class="literal">relation_uri</code>: relation URI for search term.
        </p></li><li class="listitem"><p>
         <code class="literal">modifiers</code>: relation modifiers for search
         term. The <code class="literal">modifiers</code> list itself of cql_nodes
	 each of type <code class="literal">ST</code>.
        </p></li></ul></div><p>
     </p><p>
      The boolean node represents both <code class="literal">and</code>,
      <code class="literal">or</code>, not as well as
      proximity.
      </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
         <code class="literal">left</code> and <code class="literal">right</code>: left
         - and right operand respectively.
        </p></li><li class="listitem"><p>
         <code class="literal">modifiers</code>: proximity arguments.
        </p></li></ul></div><p>
     </p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="cql.to.pqf"></a>1.3.3. CQL to PQF conversion</h4></div></div></div><p>
      Conversion to PQF (and Z39.50 RPN) is tricky by the fact
      that the resulting RPN depends on the Z39.50 target
      capabilities (combinations of supported attributes). 
      In addition, the CQL and SRU operates on index prefixes
      (URI or strings), whereas the RPN uses Object Identifiers
      for attribute sets.
     </p><p>
      The CQL library of YAZ defines a <code class="literal">cql_transform_t</code>
      type. It represents a particular mapping between CQL and RPN.
      This handle is created and destroyed by the functions:
     </p><pre class="synopsis">
cql_transform_t cql_transform_open_FILE (FILE *f);
cql_transform_t cql_transform_open_fname(const char *fname);
void cql_transform_close(cql_transform_t ct);
      </pre><p>
      The first two functions create a tranformation handle from
      either an already open FILE or from a filename respectively.
     </p><p>
      The handle is destroyed by <code class="function">cql_transform_close</code> 
      in which case no further reference of the handle is allowed.
     </p><p>
      When a <code class="literal">cql_transform_t</code> handle has been created
      you can convert to RPN.
      </p><pre class="synopsis">
int cql_transform_buf(cql_transform_t ct,
                      struct cql_node *cn, char *out, int max);
      </pre><p>
      This function converts the CQL tree <code class="literal">cn</code> 
      using handle <code class="literal">ct</code>.
      For the resulting PQF, you supply a buffer <code class="literal">out</code>
      which must be able to hold at at least <code class="literal">max</code>
      characters.
     </p><p>
      If conversion failed, <code class="function">cql_transform_buf</code>
      returns a non-zero SRU error code; otherwise zero is returned
      (conversion successful).  The meanings of the numeric error
      codes are listed in the SRU specifications at
      <a class="ulink" href="http://www.loc.gov/standards/sru/resources/diagnostics-list.html" target="_top">http://www.loc.gov/standards/sru/resources/diagnostics-list.html</a>
     </p><p>
      If conversion fails, more information can be obtained by calling
      </p><pre class="synopsis">
int cql_transform_error(cql_transform_t ct, char **addinfop);
      </pre><p>
      This function returns the most recently returned numeric
      error-code and sets the string-pointer at
      <code class="literal">*addinfop</code> to point to a string containing
      additional information about the error that occurred: for
      example, if the error code is 15 (``Illegal or unsupported context
      set''), the additional information is the name of the requested
      context set that was not recognised.
     </p><p>
      The SRU error-codes may be translated into brief human-readable
      error messages using
      </p><pre class="synopsis">
const char *cql_strerror(int code);
      </pre><p>
     </p><p>
      If you wish to be able to produce a PQF result in a different
      way, there are two alternatives.
      </p><pre class="synopsis">
void cql_transform_pr(cql_transform_t ct,
                      struct cql_node *cn,
                      void (*pr)(const char *buf, void *client_data),
                      void *client_data);

int cql_transform_FILE(cql_transform_t ct,
                       struct cql_node *cn, FILE *f);
      </pre><p>
      The former function produces output to a user-defined
      output stream. The latter writes the result to an already
      open <code class="literal">FILE</code>.
     </p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="cql.to.rpn"></a>1.3.4. Specification of CQL to RPN mappings</h4></div></div></div><p>
      The file supplied to functions 
      <code class="function">cql_transform_open_FILE</code>,
      <code class="function">cql_transform_open_fname</code> follows
      a structure found in many Unix utilities.
      It consists of mapping specifications - one per line.
      Lines starting with <code class="literal">#</code> are ignored (comments).
     </p><p>
      Each line is of the form
      </p><div class="literallayout"><p><br>
       <em class="replaceable"><code>CQL pattern</code></em><code class="literal"> = </code> <em class="replaceable"><code> RPN equivalent</code></em><br>
      </p></div><p>
     </p><p>
      An RPN pattern is a simple attribute list. Each attribute pair
      takes the form:
      </p><div class="literallayout"><p><br>
       [<em class="replaceable"><code>set</code></em>] <em class="replaceable"><code>type</code></em><code class="literal">=</code><em class="replaceable"><code>value</code></em><br>
      </p></div><p>
      The attribute <em class="replaceable"><code>set</code></em> is optional.
      The <em class="replaceable"><code>type</code></em> is the attribute type,
      <em class="replaceable"><code>value</code></em> the attribute value.
     </p><p>
      The character <code class="literal">*</code> (asterisk) has special meaning
      when used in the RPN pattern.
      Each occurrence of <code class="literal">*</code> is substituted with the
      CQL matching name (index, relation, qualifier etc).
      This facility can be used to copy a CQL name verbatim to the RPN result.
     </p><p>
      The following CQL patterns are recognized:
      </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">
         <code class="literal">index.</code><em class="replaceable"><code>set</code></em><code class="literal">.</code><em class="replaceable"><code>name</code></em>
        </span></dt><dd><p>
          This pattern is invoked when a CQL index, such as 
          dc.title is converted. <em class="replaceable"><code>set</code></em>
          and <em class="replaceable"><code>name</code></em> are the context set and index
          name respectively.
          Typically, the RPN specifies an equivalent use attribute.
         </p><p>
          For terms not bound by an index the pattern
          <code class="literal">index.cql.serverChoice</code> is used.
          Here, the prefix <code class="literal">cql</code> is defined as
          <code class="literal">http://www.loc.gov/zing/cql/cql-indexes/v1.0/</code>.
          If this pattern is not defined, the mapping will fail.
         </p><p>
          The pattern, 
          <code class="literal">index.</code><em class="replaceable"><code>set</code></em><code class="literal">.*</code>
          is used when no other index pattern is matched.
        </p></dd><dt><span class="term">
         <code class="literal">qualifier.</code><em class="replaceable"><code>set</code></em><code class="literal">.</code><em class="replaceable"><code>name</code></em>
	 (DEPRECATED)
        </span></dt><dd><p>
	  For backwards compatibility, this is recognised as a synonym of
          <code class="literal">index.</code><em class="replaceable"><code>set</code></em><code class="literal">.</code><em class="replaceable"><code>name</code></em>
         </p></dd><dt><span class="term">
         <code class="literal">relation.</code><em class="replaceable"><code>relation</code></em>
        </span></dt><dd><p>
          This pattern specifies how a CQL relation is mapped to RPN.
          <em class="replaceable"><code>pattern</code></em> is name of relation
          operator. Since <code class="literal">=</code> is used as
          separator between CQL pattern and RPN, CQL relations
          including <code class="literal">=</code> cannot be
          used directly. To avoid a conflict, the names
          <code class="literal">ge</code>,
          <code class="literal">eq</code>,
          <code class="literal">le</code>,
          must be used for CQL operators, greater-than-or-equal,
          equal, less-than-or-equal respectively.
          The RPN pattern is supposed to include a relation attribute.
         </p><p>
          For terms not bound by a relation, the pattern
          <code class="literal">relation.scr</code> is used. If the pattern
          is not defined, the mapping will fail.
         </p><p>
          The special pattern, <code class="literal">relation.*</code> is used
          when no other relation pattern is matched.
         </p></dd><dt><span class="term">
         <code class="literal">relationModifier.</code><em class="replaceable"><code>mod</code></em>
        </span></dt><dd><p>
          This pattern specifies how a CQL relation modifier is mapped to RPN.
          The RPN pattern is usually a relation attribute.
         </p></dd><dt><span class="term">
         <code class="literal">structure.</code><em class="replaceable"><code>type</code></em>
        </span></dt><dd><p>
          This pattern specifies how a CQL structure is mapped to RPN.
          Note that this CQL pattern is somewhat to similar to
          CQL pattern <code class="literal">relation</code>. 
          The <em class="replaceable"><code>type</code></em> is a CQL relation.
         </p><p>
          The pattern, <code class="literal">structure.*</code> is used
          when no other structure pattern is matched.
          Usually, the RPN equivalent specifies a structure attribute.
         </p></dd><dt><span class="term">
         <code class="literal">position.</code><em class="replaceable"><code>type</code></em>
        </span></dt><dd><p>
          This pattern specifies how the anchor (position) of
          CQL is mapped to RPN.
          The <em class="replaceable"><code>type</code></em> is one
          of <code class="literal">first</code>, <code class="literal">any</code>,
          <code class="literal">last</code>, <code class="literal">firstAndLast</code>.
         </p><p>
          The pattern, <code class="literal">position.*</code> is used
          when no other position pattern is matched.
         </p></dd><dt><span class="term">
         <code class="literal">set.</code><em class="replaceable"><code>prefix</code></em>
        </span></dt><dd><p>
          This specification defines a CQL context set for a given prefix.
          The value on the right hand side is the URI for the set - 
          <span class="emphasis"><em>not</em></span> RPN. All prefixes used in
          index patterns must be defined this way.
         </p></dd><dt><span class="term">
         <code class="literal">set</code>
        </span></dt><dd><p>
          This specification defines a default CQL context set for index names.
          The value on the right hand side is the URI for the set.
         </p></dd></dl></div><p>
     </p><div class="example"><a name="example.cql.to.rpn.mapping"></a><p class="title"><b>Example 7.10. CQL to RPN mapping file</b></p><div class="example-contents"><p>
       This simple file defines two context sets, three indexes and three
       relations, a position pattern and a default structure.
      </p><pre class="programlisting">
       set.cql  = http://www.loc.gov/zing/cql/context-sets/cql/v1.1/
       set.dc   = http://www.loc.gov/zing/cql/dc-indexes/v1.0/

       index.cql.serverChoice = 1=1016
       index.dc.title         = 1=4
       index.dc.subject       = 1=21
  
       relation.&lt;             = 2=1
       relation.eq            = 2=3
       relation.scr           = 2=3

       position.any           = 3=3 6=1

       structure.*            = 4=1

      </pre><p>
       With the mappings above, the CQL query
       </p><pre class="screen">
        computer
       </pre><p>
       is converted to the PQF:
       </p><pre class="screen">
        @attr 1=1016 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "computer"
       </pre><p>
       by rules <code class="literal">index.cql.serverChoice</code>,
       <code class="literal">relation.scr</code>, <code class="literal">structure.*</code>,
       <code class="literal">position.any</code>.
      </p><p>
       CQL query
       </p><pre class="screen">
        computer^
       </pre><p>
       is rejected, since <code class="literal">position.right</code> is
       undefined.
      </p><p>
       CQL query
       </p><pre class="screen">
        &gt;my = "http://www.loc.gov/zing/cql/dc-indexes/v1.0/" my.title = x
       </pre><p>
       is converted to
       </p><pre class="screen">
        @attr 1=4 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "x"
       </pre><p>
      </p></div></div><br class="example-break"><div class="example"><a name="example.cql.to.rpn.string"></a><p class="title"><b>Example 7.11. CQL to RPN string attributes</b></p><div class="example-contents"><p>
       In this example we allow any index to be passed to RPN as
       a use attribute.
      </p><pre class="programlisting">
       # Identifiers for prefixes used in this file. (index.*)
       set.cql  = info:srw/cql-context-set/1/cql-v1.1
       set.rpn  = http://bogus/rpn
       set      = http://bogus/rpn

       # The default index when none is specified by the query
       index.cql.serverChoice     = 1=any

       index.rpn.*                = 1=*
       relation.eq                = 2=3
       structure.*                = 4=1
       position.any               = 3=3

      </pre><p>
       The <code class="literal">http://bogus/rpn</code> context set is also the default
       so we can make queries such as
       </p><pre class="screen">
        title = a
       </pre><p>
       which is converted to
       </p><pre class="screen">
        @attr 2=3 @attr 4=1 @attr 3=3 @attr 1=title "a"
       </pre><p>
      </p></div></div><br class="example-break"><div class="example"><a name="example.cql.to.rpn.bathprofile"></a><p class="title"><b>Example 7.12. CQL to RPN using Bath Profile</b></p><div class="example-contents"><p>
       The file <code class="filename">etc/pqf.properties</code> has mappings from
       the Bath Profile and Dublin Core to RPN.
       If YAZ is installed as a package it's usually located
       in <code class="filename">/usr/share/yaz/etc</code> and part of the
       development package, such as <code class="literal">libyaz-dev</code>.
      </p></div></div><br class="example-break"></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a name="cql.xcql"></a>1.3.5. CQL to XCQL conversion</h4></div></div></div><p>
      Conversion from CQL to XCQL is trivial and does not
      require a mapping to be defined.
      There three functions to choose from depending on the
      way you wish to store the resulting output (XML buffer
      containing XCQL).
      </p><pre class="synopsis">
int cql_to_xml_buf(struct cql_node *cn, char *out, int max);
void cql_to_xml(struct cql_node *cn, 
                void (*pr)(const char *buf, void *client_data),
                void *client_data);
void cql_to_xml_stdio(struct cql_node *cn, FILE *f);
      </pre><p>
      Function <code class="function">cql_to_xml_buf</code> converts
      to XCQL and stores result in a user supplied buffer of a given
      max size.
     </p><p>
      <code class="function">cql_to_xml</code> writes the result in
      a user defined output stream.
      <code class="function">cql_to_xml_stdio</code> writes to a
      a file.
     </p></div></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="soap.srw.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="tools.oid.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">4. SRU </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 2. Object Identifiers</td></tr></table></div></body></html>
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