see <xref linkend="proxy-usage"/>.
</para>
<para>
- As an option the proxy may change user identity to a less priviledged
+ As an option the proxy may change user identity to a less privileged
user.
</para>
</section>
<section id="proxy-target">
- <title>Specifying the Backend Server</title>
+ <title>Choosing the Backend Server</title>
<para>
When the proxy receives a Z39.50 Initialize Request from a Z39.50
client, it determines the backend server by the following rules:
</listitem>
</orderedlist>
</para>
+ <para>
+ If the proxy receives an SRW/SRU request, the following rules are used.
+ <orderedlist>
+ <listitem>
+ <para>If default target has Explain information with a
+ <literal>database</literal> that matches the path of the
+ HTTP request of SRW/SRU that backend server is used for
+ SRW/SRU operation.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Otherwise the service will return HTTP 404 (Not found).
+ </para>
+ </listitem>
+ </orderedlist>
+ </para>
+ <note>
+ <para>
+ We know it is stupid to only check for explain in default target.
+ It means that it is only possible to offer one SRW/SRU server.
+ We expect to improve that in the next version of the YAZ proxy.
+ </para>
+ </note>
</section>
<section id="proxy-keepalive">
<title>Keep-alive Facility</title>
<ulink url="http://xmlsoft.org/XSLT/">libXSLT</ulink> support in
order for the config file facility to be enabled.
</para>
+ <para>
+ See <xref linkend="yazproxy-schema"/> for an XML schema
+ for the configuration.
+ </para>
<tip>
<para>To check for a config file to be well-formed, the yazproxy may
be invoked without specifying a listening port, i.e.
<title>Proxy Configuration Header</title>
<para>
The proxy config file must have a root element called
- <literal>proxy</literal>. All information except an optional XML
- header must be stored within the <literal>proxy</literal> element.
+ <literal>proxy</literal> and scoped within namespace
+ <literal> xmlns="http://indexdata.dk/yazproxy/schema/0.8/</literal>.
+ All information except an optional XML header must be stored
+ within the <literal>proxy</literal> element.
</para>
<screen>
<?xml version="1.0"?>
- <proxy>
- <!-- content here .. -->
- </proxy>
+ <proxy xmlns="http://indexdata.dk/yazproxy/schema/0.8/">
+ <!-- content here .. -->
+ </proxy>
</screen>
</section>
<section id="proxy-config-target">
<para>
<screen>
<?xml version="1.0"?>
- <proxy>
+ <proxy xmlns="http://indexdata.dk/yazproxy/schema/0.8/">
<target name="server1" default="1">
<!-- description of server1 .. -->
</target>
</para>
<para>
The following sets maximum number of bytes transferred in a
- target session to 1 MB and maxinum of requests to 400.
+ target session to 1 MB and maximum of requests to 400.
<screen>
<keepalive>
<bandwidth>1048576</bandwidth>
</screen>
</para>
</section>
-
- <!-- TODO -->
- <!--
-
- <syntax type="xml" marcxml="1" stylesheet="MARC21slim2MODS.xsl"
- identifier="http://www.loc.gov/mods"
- >
- <title>MODS v2</title>
- <name>mods2</name>
- </syntax>
-
-
--->
<section id="proxy-config-syntax">
<title>syntax</title>
<para>
<literal>type</literal> should be XML. The proxy will use
preferred record syntax USMARC/MARC21 against the backend target.
</para>
- <para>To accept USMARC and offer MARCXML XML records but reject
- all other requests the following configuration could be used:
- <screen>
- <proxy>
+ <para>
+ If attribute <literal>stylesheet</literal> is given, the proxy
+ will convert XML record from server via XSLT. It is important
+ that the content from server is XML. If used in conjunction with
+ attribute <literal>marcxml</literal> the MARC to MARCXML conversion
+ takes place before the XSLT conversion takes place.
+ </para>
+ <para>
+ If attribute <literal>identifier</literal> is given that is the
+ SRW/SRU record schema identifier for the resulting output record (after
+ MARCXML and/or XSLT conversion).
+ </para>
+ <para>
+ If sub element <literal>title</literal> is given (as child element
+ of <literal>syntax</literal>, then that is the official SRW/SRU
+ name of the resulting record schema.
+ </para>
+ <para>
+ If sub element <literal>name</literal> is given that is an alias
+ for the record schema identifier. Multiple <literal>name</literal>s
+ may be specified.
+ </para>
+ <example>
+ <title>MARCXML conversion</title>
+ <para>To accept USMARC and offer MARCXML XML plus Dublin Core (via
+ XSLT conversion) but the following configuration could be used:
+ <screen>
+ <proxy>
<target name="mytarget">
+ ..
<syntax type="usmarc"/>
- <syntax type="xml" marcxml="1"/>
- <syntax type="*" error="238"/>
+ <syntax type="xml" marcxml="1"
+ identifier="info:srw/schema/1/marcxml-v1.1"
+ <title>MARCXML<title>
+ <name>marcxml<name>
+ <syntax>
+ <syntax type="xml" marcxml="1" stylesheet="MARC21slim2SRWDC.xsl"
+ identifier="info:srw/schema/1/dc-v1.1">
+ <title>Dublin Core<title>
+ <name>dc<name>
+ <syntax>
+ <syntax type="*" error="238"/>
+ ..
</target>
- </proxy>
- </screen>
+ </proxy>
+ </screen>
</para>
+ </example>
+
</section>
<section id="proxy-config-explain">
<literal>characterInfo</literal> of the <literal>information</literal>
choice.
</para>
- </section>
+ </section>
+ <section id="yazproxy-schema">
+ <title>YAZ Proxy Configuration Schema</title>
+ <para>
+ Here an XML Schema for the YAZ proxy configuration file.
+ The schema, <filename>yazproxy.xsd</filename> is located in sub
+ directory <filename>etc</filename> of the distribution.
+ </para>
+ <screen><![CDATA[
+ <?xml version="1.0"?>
+<!-- XML Schema for YAZ proxy config file.
+ $Id: reference.xml,v 1.4 2004-04-21 08:16:42 adam Exp $
+-->
+<xs:schema
+ xmlns:xs="http://www.w3.org/2001/XMLSchema"
+ xmlns:exp="http://explain.z3950.org/dtd/2.0/"
+ xmlns="http://indexdata.dk/yazproxy/schema/0.8/"
+ targetNamespace="http://indexdata.dk/yazproxy/schema/0.8/"
+ >
+ <xs:import namespace="http://explain.z3950.org/dtd/2.0/"
+ schemaLocation="zeerex-2.0.xsd"/>
+ <xs:element name="proxy">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element ref="target" minOccurs="0" maxOccurs="unbounded"/>
+ <xs:element ref="max-clients" minOccurs="0"/>
+ <xs:element ref="log" minOccurs="0"/>
+ </xs:sequence>
+ </xs:complexType>
+ </xs:element>
+
+ <xs:element name="target">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element ref="url" minOccurs="0" maxOccurs="unbounded"/>
+ <xs:element ref="target-timeout" minOccurs="0"/>
+ <xs:element ref="client-timeout" minOccurs="0"/>
+ <xs:element ref="keepalive" minOccurs="0"/>
+ <xs:element ref="limit" minOccurs="0"/>
+ <xs:element ref="attribute" minOccurs="0" maxOccurs="unbounded"/>
+ <xs:element ref="syntax" minOccurs="0" maxOccurs="unbounded"/>
+ <xs:element ref="preinit" minOccurs="0"/>
+ <xs:element name="exp:explain" minOccurs="0"/>
+ <xs:element ref="cql2rpn" minOccurs="0"/>
+ </xs:sequence>
+ <xs:attribute name="default" type="xs:string" use="optional"/>
+ <xs:attribute name="name" type="xs:string"/>
+ </xs:complexType>
+ </xs:element>
+
+ <xs:element name="url" type="xs:string"/>
+ <xs:element name="target-timeout" type="xs:integer"/>
+ <xs:element name="client-timeout" type="xs:integer"/>
+ <xs:element name="bandwidth" type="xs:integer"/>
+ <xs:element name="pdu" type="xs:integer"/>
+ <xs:element name="retrieve" type="xs:integer"/>
+ <xs:element name="preinit" type="xs:integer"/>
+ <xs:element name="cql2rpn" type="xs:string"/>
+
+ <xs:element name="keepalive">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element ref="bandwidth" minOccurs="0"/>
+ <xs:element ref="pdu" minOccurs="0"/>
+ </xs:sequence>
+ </xs:complexType>
+ </xs:element>
+ <xs:element name="limit">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element ref="bandwidth" minOccurs="0"/>
+ <xs:element ref="pdu" minOccurs="0"/>
+ <xs:element ref="retrieve" minOccurs="0"/>
+ </xs:sequence>
+ </xs:complexType>
+ </xs:element>
+
+ <xs:element name="attribute">
+ <xs:complexType>
+ <xs:attribute name="type" type="xs:string"/>
+ <xs:attribute name="value" type="xs:string"/>
+ <xs:attribute name="error" type="xs:integer"/>
+ </xs:complexType>
+ </xs:element>
+
+ <xs:element name="syntax">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element name="title" type="xs:string" minOccurs="0"/>
+ <xs:element name="name" type="xs:string" minOccurs="0"
+ maxOccurs="unbounded"/>
+ </xs:sequence>
+ <xs:attribute name="error" type="xs:string" minOccurs="0"/>
+ <xs:attribute name="type" type="xs:string" minOccurs="0"/>
+ <xs:attribute name="marcxml" type="xs:string" minOccurs="0"/>
+ <xs:attribute name="identifier" type="xs:string" minOccurs="0"/>
+ <xs:attribute name="stylesheet" type="xs:string" minOccurs="0"/>
+ </xs:complexType>
+ </xs:element>
+
+ <xs:element name="max-clients" type="xs:integer"/>
+ <xs:element name="log" type="xs:string"/>
+
+</xs:schema>
+
+]]>
+ </screen>
+ </section>
</chapter>
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