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>
</para>
</section>
+
+ <section id="query-cache">
+ <title>Query Caching</title>
+ <para>
+ Simple stateless clients often send identical Z39.50 searches
+ in a relatively short period of time (e.g. in order to produce a
+ results-list page, the next page,
+ a single full-record, etc). And for many targets, it's
+ much more expensive to produce a new result set than to
+ reuse an existing one.
+ </para>
+ <para>
+ The proxy tries to solve that by remembering the last query for each
+ backend target, so that if an identical query is received next, it
+ is turned into Present Requests rather than new Search Requests.
+ </para>
+ <note>
+ <para>
+ In a future we release will will probably allows for
+ an arbitrary-sized cache for targets supporting named result sets.
+ </para>
+ </note>
+ <para>
+ You can enable/disable query caching using option -o.
+ </para>
+ </section>
+
+ <section id="record-cache">
+ <title>Record Caching</title>
+ <para>
+ As an option, the proxy may also cache result set records for the
+ last search.
+ The proxy takes into account the Record Syntax and CompSpec.
+ The CompSpec includes simple element set names as well.
+ By default the cache is 200000 bytes per session.
+ </para>
+ </section>
+
+ <section id="query-validation">
+ <title>Query Validation</title>
+ <para>
+ The Proxy may also be configured to trap particular attributes in
+ Type-1 queries and send Bib-1 diagnostics back to the client without
+ even consulting the backend target. This facility may be useful if
+ a target does not properly issue diagnostics when unsupported attributes
+ are send to it.
+ </para>
+ </section>
+
+ <section id="record-validation">
+ <title>Record Syntax Validation</title>
+ <para>
+ The proxy may be configured to accept, reject or convert records.
+ When accepted, the target passes search/present requests to the
+ backend target under the assumption that the target can honor the
+ request (In fact it may not do that). When a record is rejected because
+ the record syntax is "unsupported" the proxy returns a diagnostic to the
+ client. Finally, the proxy may convert records.
+ </para>
+ <para>
+ The proxy can convert from MARC to MARCXML and thereby offer an
+ XML version of any MARC record as long as it is ISO2709 encoded.
+ If the proxy is compiled with libXSLT support it can also
+ perform XSLT on XML.
+ </para>
+ </section>
+
+ <section id="other-optimizations">
+ <title>Other Optimizations</title>
+ <para>
+ We've had some plans to support global caching of result set records,
+ but this has not yet been implemented.
+ </para>
+ </section>
+
<section id="proxy-config-file">
<title>Proxy Configuration File</title>
<para>
<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.
</para>
<para>
This can also be specified on the command line by using option
- <literal>-T</literal>. Refer to OPTIONS.
+ <literal>-T</literal>. Refer to OPTIONS in <xref linkend="proxy-usage"/>.
</para>
</section>
</para>
<para>
This can also be specified on the command line by using option
- <literal>-i</literal>. Refer to OPTIONS.
+ <literal>-i</literal>. Refer to OPTIONS in <xref linkend="proxy-usage"/>.
</para>
</section>
</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>
</para>
</section>
</section>
-
- <section id="query-cache">
- <title>Query Caching</title>
- <para>
- Simple stateless clients often send identical Z39.50 searches
- in a relatively short period of time (e.g. in order to produce a
- results-list page, the next page,
- a single full-record, etc). And for many targets, it's
- much more expensive to produce a new result set than to
- reuse an existing one.
- </para>
- <para>
- The proxy tries to solve that by remembering the last query for each
- backend target, so that if an identical query is received next, it
- is turned into Present Requests rather than new Search Requests.
- </para>
- <note>
- <para>
- In a future we release will will probably allows for
- an arbitrary-sized cache for targets supporting named result sets.
- </para>
- </note>
- <para>
- You can enable/disable query caching using option -o.
- </para>
- </section>
-
- <section id="record-cache">
- <title>Record Caching</title>
- <para>
- As an option, the proxy may also cache result set records for the
- last search.
- The proxy takes into account the Record Syntax and CompSpec.
- The CompSpec includes simple element set names as well.
- By default the cache is 200000 bytes per session.
- </para>
- </section>
-
- <section id="query-validation">
- <title>Query Validation</title>
- <para>
- The Proxy may also be configured to trap particular attributes in
- Type-1 queries and send Bib-1 diagnostics back to the client without
- even consulting the backend target. This facility may be useful if
- a target does not properly issue diagnostics when unsupported attributes
- are send to it.
- </para>
- </section>
-
- <section id="record-validation">
- <title>Record Syntax Validation</title>
- <para>
- The proxy may be configured to accept, reject or convert records.
- When accepted, the target passes search/present requests to the
- backend target under the assumption that the target can honor the
- request (In fact it may not do that). When a record is rejected because
- the record syntax is "unsupported" the proxy returns a diagnostic to the
- client. Finally, the proxy may convert records.
- </para>
- <para>
- The proxy can convert from MARC to MARCXML and thereby offer an
- XML version of any MARC record as long as it is ISO2709 encoded.
- If the proxy is compiled with libXSLT support it can also
- perform XSLT on XML.
- </para>
- </section>
-
- <section id="other-optimizations">
- <title>Other Optimizations</title>
- <para>
- We've had some plans to support global caching of result set records,
- but this has not yet been implemented.
- </para>
- </section>
-
<section id="proxy-usage">
<title>Proxy Usage (man page)</title>
<refentry id="yazproxy-man">
<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 1.5 2004-04-21 13:08:21 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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