+ <note>
+ <para>
+ It is not possible to carry information about record types or
+ similar to Zebra when using extended services, due to
+ limitations of the <ulink url="&url.z39.50;">Z39.50</ulink>
+ protocol. Therefore, indexing filters can not be chosen on a
+ per-record basis. One and only one general XML indexing filter
+ must be defined.
+ <!-- but because it is represented as an OID, we would need some
+ form of proprietary mapping scheme between record type strings and
+ OIDs. -->
+ <!--
+ However, as a minimum, it would be extremely useful to enable
+ people to use MARC21, assuming grs.marcxml.marc21 as a record
+ type.
+ -->
+ </para>
+ </note>
+
+
+ <sect2 id="administration-extended-services-z3950">
+ <title>Extended services in the Z39.50 protocol</title>
+
+ <para>
+ The <ulink url="&url.z39.50;">Z39.50</ulink> standard allows
+ servers to accept special binary <emphasis>extended services</emphasis>
+ protocol packages, which may be used to insert, update and delete
+ records into servers. These carry control and update
+ information to the servers, which are encoded in seven package fields:
+ </para>
+
+ <table id="administration-extended-services-z3950-table" frame="top">
+ <title>Extended services Z39.50 Package Fields</title>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Parameter</entry>
+ <entry>Value</entry>
+ <entry>Notes</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><literal>type</literal></entry>
+ <entry><literal>'update'</literal></entry>
+ <entry>Must be set to trigger extended services</entry>
+ </row>
+ <row>
+ <entry><literal>action</literal></entry>
+ <entry><literal>string</literal></entry>
+ <entry>
+ Extended service action type with
+ one of four possible values: <literal>recordInsert</literal>,
+ <literal>recordReplace</literal>,
+ <literal>recordDelete</literal>,
+ and <literal>specialUpdate</literal>
+ </entry>
+ </row>
+ <row>
+ <entry><literal>record</literal></entry>
+ <entry><literal>XML string</literal></entry>
+ <entry>An XML formatted string containing the record</entry>
+ </row>
+ <row>
+ <entry><literal>syntax</literal></entry>
+ <entry><literal>'xml'</literal></entry>
+ <entry>Only XML record syntax is supported</entry>
+ </row>
+ <row>
+ <entry><literal>recordIdOpaque</literal></entry>
+ <entry><literal>string</literal></entry>
+ <entry>
+ Optional client-supplied, opaque record
+ identifier used under insert operations.
+ </entry>
+ </row>
+ <row>
+ <entry><literal>recordIdNumber </literal></entry>
+ <entry><literal>positive number</literal></entry>
+ <entry>Zebra's internal system number, only for update
+ actions.
+ </entry>
+ </row>
+ <row>
+ <entry><literal>databaseName</literal></entry>
+ <entry><literal>database identifier</literal></entry>
+ <entry>
+ The name of the database to which the extended services should be
+ applied.
+ </entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+
+ <para>
+ The <literal>action</literal> parameter can be any of
+ <literal>recordInsert</literal> (will fail if the record already exists),
+ <literal>recordReplace</literal> (will fail if the record does not exist),
+ <literal>recordDelete</literal> (will fail if the record does not
+ exist), and
+ <literal>specialUpdate</literal> (will insert or update the record
+ as needed).
+ </para>
+
+ <para>
+ During a <literal>recordInsert</literal> action, the
+ usual rules for internal record ID generation apply, unless an
+ optional <literal>recordIdNumber</literal> Zebra internal ID or a
+ <literal>recordIdOpaque</literal> string identifier is assigned.
+ The default ID generation is
+ configured using the <literal>recordId:</literal> from
+ <filename>zebra.cfg</filename>.
+ </para>
+
+ <para>
+ The actions <literal>recordReplace</literal> or
+ <literal>recordDelete</literal> need specification of the additional
+ <literal>recordIdNumber</literal> parameter, which must be an
+ existing Zebra internal system ID number, or the optional
+ <literal>recordIdOpaque</literal> string parameter.
+ </para>
+
+ <para>
+ When retrieving existing
+ records indexed with GRS indexing filters, the Zebra internal
+ ID number is returned in the field
+ <literal>/*/id:idzebra/localnumber</literal> in the namespace
+ <literal>xmlns:id="http://www.indexdata.dk/zebra/"</literal>,
+ where it can be picked up for later record updates or deletes.
+ </para>
+ <para>
+ Records indexed with the <literal>alvis</literal> filter
+ have similar means to discover the internal Zebra ID.
+ </para>
+
+ <para>
+ The <literal>recordIdOpaque</literal> string parameter
+ is an client-supplied, opaque record
+ identifier, which may be used under
+ insert, update and delete operations. The
+ client software is responsible for assigning these to
+ records. This identifier will
+ replace zebra's own automagic identifier generation with a unique
+ mapping from <literal>recordIdOpaque</literal> to the
+ Zebra internal <literal>recordIdNumber</literal>.
+ <emphasis>The opaque <literal>recordIdOpaque</literal> string
+ identifiers
+ are not visible in retrieval records, nor are
+ searchable, so the value of this parameter is
+ questionable. It serves mostly as a convenient mapping from
+ application domain string identifiers to Zebra internal ID's.
+ </emphasis>
+ </para>
+ </sect2>
+
+
+ <sect2 id="administration-extended-services-yaz-client">
+ <title>Extended services from yaz-client</title>
+