HTTP requests that accesses a remote triplestore via HTTP
</para>
<para>
- Configuration consists of one or more db elements. Each db element
- describes how to access a specific database. The db element takes
- attributes name of Z39.50 database (<literal>path</literal>) and
- HTTP access point of triplestore (<literal>uri</literal>).
- Optionally, the schema for the database may be given with attribute
- <literal>schema</literal>.
- Each
- db element takes these elements:
- Configurable values:
+ This module only inspects Z39.50. HTTP requests are ignored (passed through).
+ When this module is in effect, the result is HTTP packages. Use
+ the <literal>http_client</literal> module after this module in the
+ route in order to contact a remote triplestore via HTTP
+ </para>
+ <para>
+ Configuration consists of an optional defaults section and one or more
+ database sections.
+ </para>
+ <para>
+ The default sections is defined with element <literal>defaults</literal>
+ and specifies the URL of the triplestore by attribute
+ <literal>uri</literal>.
+ </para>
+ <para>
+ A database section is defined with element <literal>db</literal>.
+ The <literal>db</literal> element must specify attribute
+ <literal>path</literal> which is the name of the Z39.50 database.
+ It should also include attribute <literal>uri</literal> with the
+ URL of the triplestore; unless already specified in the detaults
+ section.
+ The element-set-name / schema for the database may be given with
+ attribute <literal>schema</literal>.
+ A db configuration may also include settings from another db section -
+ specified by the <literal>include</literal> attribute.
+ Each database section takes these elements:
<variablelist>
<varlistentry><term><prefix/></term>
<listitem>
<varlistentry><term><index type="attribute"/></term>
<listitem>
<para>
- Section used to declare RPN use attribute strings (indexes) and map
- them to BIBFRAME graph patterns.
- Items in this section are expanded during RPN query processing and
- placeholders (<literal>%s</literal>, <literal>%d</literal>,
- <literal>%t</literal>) are substituted with query terms.
- To map a given CQL index (e.g the default keyword index) into
- multiple entity properties, SPARQL constructs like
- `OPTIONAL` or `UNION` could be used.
+ Section used to declare RPN/Type-1 use attribute strings (indices)
+ and map them to BIBFRAME graph patterns.
+ Items in this section are constructed during RPN query processing and
+ placeholders that are prefixed by a percent sign (<literal>%</literal>)
+ are expanded.
+ See <xref linkend="expansions">EXPANSIONS</xref>.
+ To map a given use attribute (search field) into
+ multiple entity properties, SPARQL constructs like `OPTIONAL` or
+ `UNION` can be used.
</para>
</listitem>
</varlistentry>
<varlistentry><term><present type="attribute"/></term>
<listitem>
<para>
- Section used to declare retrieval for a given element-set
+ Section used to declare retrieval for a given element-set-name
(SRU schema). The CDATA is SPARQL where <literal>%u</literal> holds
the URI of the record. This can be used to construct the resulting
record.
</variablelist>
</para>
</refsect1>
-
- <refsect1><title>SCHEMA</title>
- <literallayout><xi:include
+ <refsect1 id="expansions"><title>EXPANSIONS</title>
+ <variablelist>
+ <varlistentry><term><literal>%t</literal></term>
+ <listitem>
+ <para>
+ The term verbatim as it appears in the Type-1 query.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term><literal>%s</literal></term>
+ <listitem>
+ <para>
+ Like <literal>%t</literal> but quoted - for general strings.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term><literal>%d</literal></term>
+ <listitem>
+ <para>
+ Term - expecting an integer.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term><literal>%u</literal></term>
+ <listitem>
+ <para>
+ Like <literal>%t</literal>, but with prefix <literal><</literal>
+ and suffix <literal>></literal> - for URIs.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term><literal>%v</literal></term>
+ <listitem>
+ <para>
+ Expands to a SPARQL local variable <literal>?v...</literal>. Allows
+ the use of a local SPARQL variable for each Attribute+Term in the
+ Type-1 query.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1><title>SCHEMA</title>
+ <literallayout><xi:include
xi:href="filter_sparql.rnc"
xi:parse="text"
xmlns:xi="http://www.w3.org/2001/XInclude" />
</para>
<para>
This returns one row for each work. Titles, authors, and subjects
- are all optional. If they repeat, the repeated values are concatenated into
- a single field, separated by semicolons. This is done by the GROUP_DIGEST
- function that is specific to the Virtuoso back end.
+ are all optional. If they repeat, the repeated values are concatenated
+ into a single field, separated by semicolons. This is done by the
+ GROUP_DIGEST function that is specific to the Virtuoso back end.
</para>
<para>
- This example supports use attributes 4 (title), 1003 (author), 21 (subject),
- and 1016 (keyword) which matches any literal in a triplet that refers to the
- work, so it works for the titleValue in the workTitle, as well as the label
- in the subject, and what ever else there may be. Like the preceding example,
- the matching is by a simple substring, case sensitive. A more realistic term
- matching could be done with regular expressions, at the cost of some readability
+ This example supports use attributes 4 (title), 1003 (author),
+ 21 (subject), and 1016 (keyword) which matches any literal in a
+ triplet that refers to the work, so it works for the titleValue in
+ the workTitle, as well as the label in the subject, and what ever
+ else there may be. Like the preceding example, the matching is by a
+ simple substring, case sensitive. A more realistic term matching could
+ be done with regular expressions, at the cost of some readability
portability, and performance.
</para>
</refsect1>
<refsect1><title>EXAMPLE</title>
<para>
Configuration for database "instance". Like "work" above this uses SELECT
- to return row-based data, this time from the instances. This is not deduplicated,
- so if an instance has two titles, we get two rows, and if it also has
- two formats, we get four rows. The DISTINCT in the SELECT
+ to return row-based data, this time from the instances.
+ This is not deduplicated, so if an instance has two titles, we get two
+ rows, and if it also has two formats, we get four rows.
+ The DISTINCT in the SELECT
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