+ The purpose of using settings in this way can either be to
+ control the behavior of normalization stylesheet in a database-
+ dependent way, or to easily make database-dependent values
+ available to display-logic in your user interface, without having
+ to implement complicated interactions between the user interface
+ and your configuration system.
+ </listitem>
+ </varlistentry>
+ </variablelist> <!-- attributes to metadata -->
+
+ </listitem>
+ </varlistentry>
+ </variablelist> <!-- Data elements in service directive -->
+ </listitem>
+ </varlistentry>
+ </variablelist> <!-- Data elements in server directive -->
+ </refsect2>
+
+ </refsect1>
+
+ <refsect1><title>EXAMPLE</title>
+ <para>Below is a working example configuration:
+ <screen><![CDATA[
+<?xml version="1.0" encoding="UTF-8"?>
+<pazpar2 xmlns="http://www.indexdata.com/pazpar2/1.0">
+
+<server>
+ <listen port="9004"/>
+ <proxy host="us1.indexdata.com" myurl="us1.indexdata.com"/>
+
+ <!-- optional ICU ranking configuration example -->
+ <!--
+ <icu_chain id="el:word" locale="el">
+ <normalize rule="[:Control:] Any-Remove"/>
+ <tokenize rule="l"/>
+ <normalize rule="[[:WhiteSpace:][:Punctuation:]] Remove"/>
+ <casemap rule="l"/>
+ <index/>
+ </icu_chain>
+ -->
+
+ <service>
+ <metadata name="title" brief="yes" sortkey="skiparticle" merge="longest" rank="6"/>
+ <metadata name="isbn" merge="unique"/>
+ <metadata name="date" brief="yes" sortkey="numeric" type="year" merge="range"
+ termlist="yes"/>
+ <metadata name="author" brief="yes" termlist="yes" merge="longest" rank="2"/>
+ <metadata name="subject" merge="unique" termlist="yes" rank="3"/>
+ <metadata name="url" merge="unique"/>
+ </service>
+</server>
+
+</pazpar2>
+]]></screen>
+ </para>
+ </refsect1>
+
+ <refsect1 id="target_settings"><title>TARGET SETTINGS</title>
+ <para>
+ Pazpar2 features a cunning scheme by which you can associate various
+ kinds of attributes, or settings with search targets. This can be done
+ through XML files which are read at startup; each file can associate
+ one or more settings with one or more targets. The file format is generic
+ in nature, designed to support a wide range of application requirements. The
+ settings can be purely technical things, like, how to perform a title
+ search against a given target, or it can associate arbitrary name=value
+ pairs with groups of targets -- for instance, if you would like to
+ place all commercial full-text bases in one group for selection
+ purposes, or you would like to control what targets are accessible
+ to users by default. Per-database settings values can even be used
+ to drive sorting, facet/termlist generation, or end-user interface display
+ logic.
+ </para>
+
+ <para>
+ During startup, Pazpar2 will recursively read a specified directory
+ (can be identified in the pazpar2.cfg file or on the command line), and
+ process any settings files found therein.
+ </para>
+
+ <para>
+ Clients of the Pazpar2 webservice interface can selectively override
+ settings for individual targets within the scope of one session. This
+ can be used in conjunction with an external authentication system to
+ determine which resources are to be accessible to which users. Pazpar2
+ itself has no notion of end-users, and so can be used in conjunction
+ with any type of authentication system. Similarly, the authentication
+ tokens submitted to access-controlled search targets can similarly be
+ overridden, to allow use of Pazpar2 in a consortial or multi-library
+ environment, where different end-users may need to be represented to
+ some search targets in different ways. This, again, can be managed
+ using an external database or other lookup mechanism. Setting overrides
+ can be performed either using the 'init' or the 'settings' webservice
+ command.
+ </para>
+
+ <para>
+ In fact, every setting that applies to a database (except pz:id, which
+ can only be used for filtering targets to use for a search) can be overridden
+ on a per-session basis. This allows the client to override specific CCL fields
+ for searching, etc., to meet the needs of a session or user.
+ </para>
+
+ <para>
+ Finally, as an extreme case of this, the webservice client can
+ introduce entirely new targets, on the fly, as part of the init or
+ settings command. This is useful if you desire to manage information
+ about your search targets in a separate application such as a database.
+ You do not need any static settings file whatsoever to run Pazpar2 -- as
+ long as the webservice client is prepared to supply the necessary
+ information at the beginning of every session.
+ </para>
+
+ <note>
+ <para>
+ The following discussion of practical issues related to session and settings
+ management are cast in terms of a user interface based on Ajax/Javascript
+ technology. It would apply equally well to many other kinds of browser-based logic.
+ </para>
+ </note>
+
+ <para>
+ Typically, a Javascript client is not allowed to directly alter the parameters
+ of a session. There are two reasons for this. One has to do with access
+ to information; typically, information about a user will be stored in a
+ system on the server side, or it will be accessible in some way from the server.
+ However, since the Javascript client cannot be entirely trusted (some hostile
+ agent might in fact 'pretend' to be a regular ws client), it is more robust
+ to control session settings from scripting that you run as part of your
+ webserver. Typically, this can be handled during the session initialization,
+ as follows:
+ </para>
+
+ <para>
+ Step 1: The Javascript client loads, and asks the webserver for a new Pazpar2
+ session ID. This can be done using a Javascript call, for instance. Note that
+ it is possible to submit Ajax HTTPXmlRequest calls either to Pazpar2 or to the
+ webserver that Pazpar2 is proxying for. See (XXX Insert link to Pazpar2 protocol).
+ </para>
+
+ <para>
+ Step 2: Code on the webserver authenticates the user, by database lookup,
+ LDAP access, NCIP, etc. Determines which resources the user has access to,
+ and any user-specific parameters that are to be applied during this session.
+ </para>
+
+ <para>
+ Step 3: The webserver initializes a new Pazpar2 settings, and sets user-specific
+ parameters as necessary, using the init webservice command. A new session ID is
+ returned.
+ </para>
+
+ <para>
+ Step 4: The webserver returns this session ID to the Javascript client, which then
+ uses the session ID to submit searches, show results, etc.
+ </para>
+
+ <para>
+ Step 5: When the Javascript client ceases to use the session, Pazpar2 destroys
+ any session-specific information.
+ </para>
+
+ <refsect2><title>SETTINGS FILE FORMAT</title>
+ <para>
+ Each file contains a root element named <settings>. It may
+ contain one or more <set> elements. The settings and set
+ elements may contain the following attributes. Attributes in the set node
+ overrides those in the setting root element. Each set node must
+ specify (directly, or inherited from the parent node) at least a
+ target, name, and value.
+ </para>
+
+ <variablelist>
+ <varlistentry>
+ <term>target</term>
+ <listitem>
+ <para>
+ This specifies the search target to which this setting should be
+ applied. Targets are identified by their Z39.50 URL, generally
+ including the host, port, and database name, (e.g.
+ <literal>bagel.indexdata.com:210/marc</literal>).
+ Two wildcard forms are accepted:
+ * (asterisk) matches all known targets;
+ <literal>bagel.indexdata.com:210/*</literal> matches all
+ known databases on the given host.
+ </para>
+ <para>
+ A precedence system determines what happens if there are
+ overlapping values for the same setting name for the same
+ target. A setting for a specific target name overrides a
+ setting which specifies target using a wildcard. This makes it
+ easy to set defaults for all targets, and then override them
+ for specific targets or hosts. If there are
+ multiple overlapping settings with the same name and target
+ value, the 'precedence' attribute determines what happens.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>name</term>
+ <listitem>
+ <para>
+ The name of the setting. This can be anything you like.
+ However, Pazpar2 reserves a number of setting names for
+ specific purposes, all starting with 'pz:', and it is a good
+ idea to avoid that prefix if you make up your own setting
+ names. See below for a list of reserved variables.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>value</term>
+ <listitem>
+ <para>
+ The value of the setting. Generally, this can be anything you
+ want -- however, some of the reserved settings may expect
+ specific kinds of values.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>precedence</term>
+ <listitem>
+ <para>
+ This should be an integer. If not provided, the default value
+ is 0. If two (or more) settings have the same content for
+ target and name, the precedence value determines the outcome.
+ If both settings have the same precedence value, they are both
+ applied to the target(s). If one has a higher value, then the
+ value of that setting is applied, and the other one is ignored.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>
+ By setting defaults for target, name, or value in the root
+ settings node, you can use the settings files in many different
+ ways. For instance, you can use a single file to set defaults for
+ many different settings, like search fields, retrieval syntaxes,
+ etc. You can have one file per server, which groups settings for
+ that server or target. You could also have one file which associates
+ a number of targets with a given setting, for instance, to associate
+ many databases with a given category or class that makes sense
+ within your application.
+ </para>
+
+ <para>
+ The following examples illustrate uses of the settings system to
+ associate settings with targets to meet different requirements.
+ </para>
+
+ <para>
+ The example below associates a set of default values that can be
+ used across many targets. Note the wildcard for targets.
+ This associates the given settings with all targets for which no
+ other information is provided.
+ <screen><![CDATA[
+<settings target="*">