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+ %common;
+]>
+<!-- $Id: cql_rpn.xml,v 1.1 2007-01-18 11:32:42 marc Exp $ -->
+<refentry>
+ <refmeta>
+ <refentrytitle>query_rewrite</refentrytitle>
+ <manvolnum>3mp</manvolnum>
+ <refmiscinfo>Metaproxy Module</refmiscinfo>
+</refmeta>
+
+ <refnamediv>
+ <refname>cql_rpn</refname>
+ <refpurpose>Metaproxy CQL to RPN Query Language Transforming Module</refpurpose>
+ </refnamediv>
+
+ <refsect1><title>DESCRIPTION</title>
+ <para>
+ A query language transforming filter which catches Z39.50
+ <literal>searchRequest</literal>
+ packages containing <literal>CQL</literal> queries, transforms
+ those to <literal>RPN</literal> queries,
+ and sends the <literal>searchRequests</literal> on to the next
+ filters.
+ </para>
+ <para>
+ The filter takes only one configuration parameter, namely the path
+ of the standard <literal>YAZ</literal>
+ <literal>CQL</literal>-to-<literal>CQL</literal> configuration
+ file. See the <ulink url="&url.yaz;">YAZ</ulink> manual for
+ configuration file syntax and details.
+ </para>
+ <para>
+ A common and wellknown challenge is that the ZeeRex SRU
+ Explain config file used in the <literal>sru_z3950</literal>
+ filter and the <literal>CQL</literal> translation configuration
+ file used in this filter must be kept in syncronization.
+ Syncronization can be eased by using the provided XSLT stylesheet,
+ <literal>xml/xslt/explain2cqlpqftxt.xsl</literal>, which transforms
+ from ZeeReX Explain to the later. The example configurations have
+ been created by running:
+ <screen>
+ xsltproc xml/xslt/explain2cqlpqftxt.xsl etc/explain.xml > etc/cql2pqf.txt
+ </screen>
+ </para>
+ </refsect1>
+
+ <refsect1><title>EXAMPLES</title>
+ <para>
+ A typical configuration looks like this:
+ <screen><![CDATA[
+ <filter id="cql" type="cql_rpn">
+ <conversion file="etc/cql2pqf.txt"/>
+ </filter>
+ ]]>
+ </screen>
+ </para>
+ </refsect1>
+
+ <refsect1><title>SEE ALSO</title>
+ <para>
+ <citerefentry>
+ <refentrytitle>metaproxy</refentrytitle>
+ <manvolnum>1</manvolnum>
+ </citerefentry>
+ </para>
+ </refsect1>
+
+ ©right;
+</refentry>
+
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