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<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
-
- This file is part of the OpenLink Software Virtuoso Open-Source (VOS)
- project.
-
- Copyright (C) 1998-2018 OpenLink Software
-
- This project is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by the
- Free Software Foundation; only version 2 of the License, dated June 1991.
-
- This program is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
-
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
-
-
-->
<!--
Please use the following prefixes for IDs:
xpf_ for old XPATH functions,
xf_ for XPATH 2.0 & XQUERY 1.0 functions,
xsl_ for XSL elements,
-->
<refentry id="xpf_processXQuery">
<refmeta>
<refentrytitle>processXQuery</refentrytitle>
<refmiscinfo>XPATH</refmiscinfo>
</refmeta>
<refnamediv>
<refname>processXQuery</refname>
<refpurpose>Calls an XQuery module from XPath expression, e.g. from some XSLT or BPEL code.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis id="xpf_syn_processXQuery">
<funcprototype id="xpf_proto_processXQuery">
<funcdef>any <function>processXQuery</function></funcdef>
<paramdef><parameter>module_uri</parameter> string</paramdef>
<paramdef><optional><parameter>context</parameter> entity</optional></paramdef>
<paramdef><optional><parameter>index</parameter> integer</optional></paramdef>
<paramdef><optional><parameter>param1_name</parameter> string</optional></paramdef>
<paramdef><optional><parameter>param1_value</parameter> any</optional></paramdef>
...
<paramdef><optional><parameter>paramN_name</parameter> string</optional></paramdef>
<paramdef><optional><parameter>paramN_value</parameter> any</optional></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="xpf_desc_processXQuery"><title>Description</title>
<para>
This function takes a URI of an XQuery module and an XML entity and
calls the module with the entity as a context.
Depending on value of <parameter>index</parameter> parameter,
either the result of the module is returned 'as is' or the sequence of results is returned.
</para>
<para>
Parameters can be passed to the module by specifying additional arguments
to <function>processXQuery()</function>.
The names of parameters should appear in argument list without the leading '$' sign.
Unlike <link linkend="fn_xquery_eval"><function>xquery_eval()</function></link> function, parameter
can not be ignored depending on the type of its value.
If the same name appears more than once in the vector, the last name/value pair is
used and all preceding pairs with this name are silently ignored.
Obviously, names should be strings that are valid XPath variable names.
</para>
<para>
The XQuery standard does not offer a way of calling of a module from other XQuery expression.
The reason is that there's no need for such calling if the code is designed properly.
If an expression is re-used in various places then it should be turned into a function and
placed into an XQuery library module; one should import the module and call the function instead of
calling a non-library module. It is possible to use <function>processXQuery()</function>
in XQuery expressions but it is much better to use library modules instead, and to use
<function>processXQuery()</function> only for tricks in XPATH expressions.
</para>
<para>
For compatibility, the <function>processXQuery()</function> function can also be called as
<function>http://schemas.oracle.com/xpath/extension:processXQuery()</function>.
</para>
</refsect1>
<refsect1 id="xpf_params_processXQuery"><title>Parameters</title>
<refsect2><title>module_uri</title>
<para>URI pointing to the location of an XQuery module. It can be absolute or relative.
A relative <title>module_uri</title> should be resolved before use, this requires base URI information.
Base URI can be declared explicitly by "__base_uri" parameter in XPATH or
"declare base-uri" setter in XQuery.
If not declared but the expression is a part of some stylesheet or XQuery module then the URI of module is
used as a base URI.
A run-time error is signalled if the URI is relative and the expression does not contain explicit declaration and the expression is neither in a stylesheet nor in a module.
</para></refsect2>
<refsect2><title>index</title>
<para>Result index. If omitted a value of 1 is assumed,
meaning only the first result is returned. If a value of 0 is supplied then a (flatten) sequence of all results is returned.
(Note that if a non-zero value is specified then the returned value still can be a sequence).
</para></refsect2>
<refsect2><title>context</title>
<para>XML entity that is the context node of module call.
If the function is called with only one argument then the current context node of the <function>processXQuery()</function> call is used as a context of module call.
(In any case, context size and context position of module call are always set to 1 and not inherited from call of <function>processXQuery()</function>.)
</para></refsect2>
<refsect2><title>paramI_name</title>
<para>Name of parameter to be passed to the
XSLT engine for use in the transformation.</para></refsect2>
<refsect2><title>paramI_value</title>
<para>Value of parameter with name specified by <parameter>paramI_name</parameter>.</para></refsect2>
</refsect1>
<refsect1 id="xpf_ret_processXQuery"><title>Return Types</title><para>The type of return value depends on type of value returned by module.</para></refsect1>
<!--
<refsect1 id="xpf_errors_processXQuery"><title>Errors</title>
<table><title>Errors signalled by</title>
<tgroup cols="4">
<thead><row><entry>SQLState</entry><entry>Error Code</entry><entry>Error Text</entry><entry>Description</entry></row></thead>
<tbody>
<row>
<entry><errorcode></errorcode></entry>
<entry><errorcode></errorcode></entry>
<entry><errorname></errorname></entry>
<entry></entry>
</row>
</tbody>
</tgroup>
</table>
</refsect1>
-->
<refsect1 id="xpf_examples_processXQuery"><title>Examples</title>
<example id="xpf_ex_processXQuery"><title>Call of XQuery in XSLT</title>
<para>Sample templates put the result of the call of module "mymodule.xq" for context node into the resulting document.
This assumes that both the stylesheet and XQuery module "mymodule.xq" reside in the same directory so relative a URI "mymodule.xq"
can be resolved using the URI of the stylesheet as base URI.
</para>
<screen><![CDATA[
<xsl:template match="myelement">
<xsl:copy-of select="processXQuery('mymodule.xq')"/>
</xsl:template>
]]></screen>
<para>This is equivalent with the following template:
</para>
<screen><![CDATA[
<xsl:template match="myelement">
<xsl:copy-of select="processXQuery('mymodule.xq', current(), 1)"/>
</xsl:template>
]]></screen>
</example>
</refsect1>
<refsect1 id="xpf_seealso_processXQuery"><title>See Also</title>
<para><link linkend="fn_xquery_eval"><function>xquery_eval()</function></link></para>
<para><link linkend="xpf_processXSLT"><function>processXSLT()</function></link></para>
<para><link linkend="xpf_processXSQL"><function>processXSQL()</function></link></para>
</refsect1>
</refentry>
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