-<!-- $Id: tools.xml,v 1.56 2007-02-08 09:03:31 adam Exp $ -->
+<!-- $Id: tools.xml,v 1.57 2007-02-08 11:36:59 adam Exp $ -->
<chapter id="tools"><title>Supporting Tools</title>
<para>
</example>
</sect1>
+ <sect1 id="tools.retrieval">
+ <title>Retrieval Facility</title>
+ <para>
+ YAZ version 2.1.20 or later includes a Retrieval facility tool
+ which allows a SRU/Z39.50 to describe itself and perform record
+ conversions. The idea is the following:
+
+ <itemizedlist>
+ <listitem>
+ <para>
+ An SRU/Z39.50 client sends a retrieval request which includes
+ a combination of the following parameters: syntax (format),
+ schema (or element set name).
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ The retrieval facility is invoked with parameters in a
+ server/proxy. The retrieval facility matches the parameters a set of
+ "supported" retrieval types.
+ If there is no match, the retrieval signals an error
+ (syntax and / or schema not supported).
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ For a successful match, the backend is invoked with the same
+ or altered retrieval parameters (syntax, schema). If
+ a record is received from the backend, it is converted to the
+ frontend name / syntax.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ The resulting record is sent back the client and tagged with
+ the frontend syntax / schema.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+ </para>
+ <para>
+ The Retrieval facility is driven by an XML configuration. The
+ configuration is neither Z39.50 ZeeRex or SRU ZeeRex. But it
+ should be easy to generate both of them from the XML configuration.
+ (unfortunately the two versions
+ of ZeeRex differ substantially in this regard).
+ </para>
+ <sect2 id="tools.retrieval.format">
+ <title>Retrieval XML format</title>
+ <para>
+ All elements should be covered by namespace
+ <literal>http://indexdata.com/yaz</literal> .
+ The root element node must be <literal>retrievalinfo</literal>.
+ </para>
+ <para>
+ The <literal>retrievalinfo</literal> must include one or
+ more <literal>retrieval</literal> elements. Each
+ <literal>retrieval</literal> defines specific combination of
+ syntax, name and identifier supported by this retrieval service.
+ </para>
+ <para>
+ The <literal>retrieval</literal> element may include any of the
+ following attributes:
+ <variablelist>
+ <varlistentry><term><literal>syntax</literal> (REQUIRED)</term>
+ <listitem>
+ <para>
+ Defines the record syntax. Possible values is any
+ of the names defined in YAZ' OID database or a raw
+ OID in (n.n ... n).
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term><literal>name</literal> (OPTIONAL)</term>
+ <listitem>
+ <para>
+ Defines the name of the retrieval format. This can be
+ any string. For SRU, the value, is equivalent to schema (short-hand);
+ for Z39.50 it's equivalent to simple element set name.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term><literal>identifier</literal> (OPTIONAL)</term>
+ <listitem>
+ <para>
+ Defines the URI schema name of the retrieval format. This can be
+ any string. For SRU, the value, is equivalent to URI schema.
+ For Z39.50, there is no equivalent.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ <para>
+ The <literal>retrieval</literal> may include one
+ <literal>backend</literal> element. If a <literal>backend</literal>
+ element is given, it specifies how the records are retrieved by
+ some backend and how the records are converted from the backend to
+ the "frontend".
+ </para>
+ <para>
+ The attributes, <literal>name</literal> and <literal>syntax</literal>
+ may be specified for the <literal>backend</literal> element. These
+ semantics of these attributes is equivalent to those for the
+ <literal>retrieval</literal>. However, these values are passed to
+ the "backend".
+ </para>
+ <para>
+ The <literal>backend</literal> element may includes one or more
+ conversion instructions (as children elements). The supported
+ conversions are:
+ <variablelist>
+ <varlistentry><term><literal>marc</literal></term>
+ <listitem>
+ <para>
+ The <literal>marc</literal> element specifies a conversion
+ to - and from ISO2709 encoded MARC and
+ <ulink url="&url.marcxml;">&marcxml;</ulink>/MarcXchange.
+ The following attributes may be specified:
+
+ <variablelist>
+ <varlistentry><term><literal>inputformat</literal> (REQUIRED)</term>
+ <listitem>
+ <para>
+ Format of input. Supported values are
+ <literal>marc</literal> (for ISO2709); and <literal>xml</literal>
+ for MARCXML/MarcXchange.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry><term><literal>outputformat</literal> (REQUIRED)</term>
+ <listitem>
+ <para>
+ Format of output. Supported values are
+ <literal>line</literal> (MARC line format);
+ <literal>marcxml</literal> (for MARCXML),
+ <literal>marc</literal> (ISO2709),
+ <literal>marcxhcange</literal> (for MarcXchange).
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry><term><literal>inputcharset</literal> (OPTIONAL)</term>
+ <listitem>
+ <para>
+ Encoding of input. For XML input formats, this need not
+ be given, but for ISO2709 based inputformats, this should
+ be set to the encoding used. For MARC21 records, a common
+ inputcharset value would be <literal>marc-8</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry><term><literal>outputcharset</literal> (OPTIONAL)</term>
+ <listitem>
+ <para>
+ Encoding of output. If outputformat is XML based, it is
+ strongly recommened to use <literal>utf-8</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ </variablelist>
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term><literal>xslt</literal></term>
+ <listitem>
+ <para>
+ The <literal>xslt</literal> element specifies a conversion
+ via &xslt;. The following attributes may be specified:
+
+ <variablelist>
+ <varlistentry><term><literal>stylesheet</literal> (REQUIRED)</term>
+ <listitem>
+ <para>
+ Stylesheet file.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ </sect2>
+ <sect2 id="tools.retrieval.examples">
+ <title>Retrieval Facility Examples</title>
+ <example>
+ <title id="tools.retrieval.marc21">MARC21 backend</title>
+ <para>
+ A typical way to use the retrieval facility is to enable XML
+ for servers that only supports ISO2709 encoded MARC21 records.
+ </para>
+ <programlisting><![CDATA[
+ <retrievalinfo>
+ <retrieval syntax="usmarc" name="F"/>
+ <retrieval syntax="usmarc" name="B"/>
+ <retrieval syntax="xml" name="marcxml"
+ identifier="info:srw/schema/1/marcxml-v1.1">
+ <backend syntax="usmarc" name="F">
+ <marc inputformat="marc" outputformat="marcxml"
+ inputcharset="marc-8"/>
+ </backend>
+ </retrieval>
+ <retrieval syntax="xml" name="dc">
+ <backend syntax="usmarc" name="F">
+ <marc inputformat="marc" outputformat="marcxml"
+ inputcharset="marc-8"/>
+ <xslt stylesheet="MARC21slim2DC.xsl"/>
+ </backend>
+ </retrieval>
+ </retrievalinfo>
+]]>
+ </programlisting>
+ <para>
+ This means that our frontend supports:
+ <itemizedlist>
+ <listitem>
+ <para>
+ MARC21 F(ull) records.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ MARC21 B(rief) records.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ MARCXML records.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Dublin core records.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para>
+ </example>
+ </sect2>
+ <sect2>
+ <title>API</title>
+ <para>
+ It should be easy to use the retrieval systems from applications. Refer
+ to the headers
+ <filename>yaz/retrieval.h</filename> and
+ <filename>yaz/record_conv.h</filename>.
+ </para>
+ </sect2>
+ </sect1>
</chapter>
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