<?xml version="1.0" encoding="UTF-8"?>
<chapter xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="xml"
    xmlns:xlink="http://www.w3.org/1999/xlink">
  <title>XML Support - Dealing with XML Payloads</title>

  <section id="xml-intro">
    <title>Introduction</title>
    <para>
      Spring Integration's XML support extends the core of Spring Integration with
      the following components:
    </para>
    <itemizedlist>
        <listitem>
            <para><emphasis><link linkend='xml-transformation'>Marshalling Transformer</link></emphasis></para>
        </listitem>
        <listitem>
            <para><emphasis><link linkend='xml-transformation'>Unmarshalling Transformer</link></emphasis></para>
        </listitem>
        <listitem>
            <para><emphasis><link linkend='xml-transformation'>Xslt Transformer</link></emphasis></para>
        </listitem>
        <listitem>
            <para><emphasis><link linkend='xml-xpath-transformer'>XPath Transformer</link></emphasis></para>
        </listitem>
        <listitem>
            <para><emphasis><link linkend='xml-xpath-splitting'>XPath Splitter</link></emphasis></para>
        </listitem>
        <listitem>
            <para><emphasis><link linkend='xml-xpath-routing'>XPath Router</link></emphasis></para>
        </listitem>
        <listitem>
            <para><emphasis><link linkend='xml-xpath-header-enricher'>XPath Header Enricher</link></emphasis></para>
        </listitem>
        <listitem>
            <para><emphasis><link linkend='xml-xpath-filter'>XPath Filter</link></emphasis></para>
        </listitem>
        <listitem>
            <para><emphasis><link linkend='xml-validating-filter'>Validating Filter</link></emphasis></para>
        </listitem>

    </itemizedlist>
    <para>
      These components are designed to make working with XML messages in Spring Integration simple.
      The provided messaging components are designed to work with XML represented
      in a range of formats including instances of
      <classname>java.lang.String</classname>, <interfacename>org.w3c.dom.Document</interfacename>
      and <interfacename>javax.xml.transform.Source</interfacename>.  It should be noted however that
      where a DOM representation is required, for example in order to evaluate an XPath expression,
      the <classname>String</classname> payload will be converted into the required type and then
      converted back again to <classname>String</classname>. Components that require an instance of
      <interfacename>DocumentBuilder</interfacename> will create a namespace-aware instance if one is
      not provided. In cases where you require greater control over document creation, you can
      provide an appropriately configured instance of <interfacename>DocumentBuilder</interfacename>.
    </para>
  </section>
  <section id="xpath-namespace-support">
    <title>Namespace Support</title>
    <para>
    All components within the Spring Integration XML module provide namespace
    support. In order to enable namespace support, you need to import the respective
    schema for the Spring Integration XML Module. A typical setup is shown below:
    </para>
    <programlisting language="xml"><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:int="http://www.springframework.org/schema/integration"
  xmlns:int-xml="http://www.springframework.org/schema/integration/xml"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/integration
    http://www.springframework.org/schema/integration/spring-integration.xsd
    http://www.springframework.org/schema/integration/xml
    http://www.springframework.org/schema/integration/xml/spring-integration-xml.xsd">
</beans>]]></programlisting>

    <section id="xml-xpath-expressions">
        <title>XPath Expressions</title>
        <para>
            Many of the components within the Spring Integration XML module work
            with XPath Expressions. Each of those components will either reference
            an XPath Expression that has been defined as top-level element or via
            a nested <code>&lt;xpath-expression/&gt;</code> element.
        </para>
        <para>
            All forms of XPath expressions result in the creation of an
            <interfacename>XPathExpression</interfacename> using the Spring
            <classname>org.springframework.xml.xpath.XPathExpressionFactory</classname>.
            When creating XPath expressions, the best XPath implementation that
            is available on the classpath is being used, either JAXP 1.3+ or Jaxen,
            whereby JAXP is preferred.
        </para>
        <note>
            Spring Integration under the covers uses the XPath functionality as
            provided by the <emphasis>Spring Web Services</emphasis> project
            (http://www.springsource.org/spring-web-services). Specifically,
            Spring Web Services' XML module (spring-xml-x.x.x.jar) is being used.
            Therefore, for a deeper understanding, please refer to the respective
            documentation as well at:

            <itemizedlist>
		        <listitem>
		            <ulink url="http://static.springsource.org/spring-ws/sites/2.0/reference/html/common.html#xpath">
		                http://static.springsource.org/spring-ws/sites/2.0/reference/html/common.html#xpath
		            </ulink>
		        </listitem>
	        </itemizedlist>

        </note>
        <para>
            Here is an overview of all available configuration parameters of the
            <code>xpath-expression</code> element:
        </para>
        <programlisting language="xml"><![CDATA[<int-xml:xpath-expression expression=""     ]]><co id="xpath-expression-xml01-co" linkends="xpath-expression-xml01" /><![CDATA[
		          id=""             ]]><co id="xpath-expression-xml02-co" linkends="xpath-expression-xml02" /><![CDATA[
		          namespace-map=""  ]]><co id="xpath-expression-xml03-co" linkends="xpath-expression-xml03" /><![CDATA[
		          ns-prefix=""      ]]><co id="xpath-expression-xml04-co" linkends="xpath-expression-xml04" /><![CDATA[
		          ns-uri="">        ]]><co id="xpath-expression-xml05-co" linkends="xpath-expression-xml05" /><![CDATA[
    <map></map>                           ]]><co id="xpath-expression-xml06-co" linkends="xpath-expression-xml06" /><![CDATA[
</int-xml:xpath-expression>]]></programlisting>
    <para>
        <calloutlist>
            <callout arearefs="xpath-expression-xml01-co" id="xpath-expression-xml01">
                <para>
                    Defines an XPath xpression.
                    <emphasis>Required</emphasis>.
                </para>
            </callout>
            <callout arearefs="xpath-expression-xml02-co" id="xpath-expression-xml02">
                <para>
                    The Identifier of the underlying bean definition. Will be an instance of
                    <classname>org.springframework.xml.xpath.XPathExpression</classname>
                    <emphasis>Optional</emphasis>.
                </para>
            </callout>
            <callout arearefs="xpath-expression-xml03-co" id="xpath-expression-xml03">
                <para>
                    Reference to a map containing namespaces. The key of the map
                    defines the namespace prefix and the value of the map sets the
                    namespace URI. It is not valid to specify both this attribute
                    and the <code>map</code> sub element, or setting the
                    <code>ns-prefix</code> and <code>ns-uri</code> attribute.
                    <emphasis>Optional</emphasis>.</para>
            </callout>
            <callout arearefs="xpath-expression-xml04-co" id="xpath-expression-xml04">
                <para>
                    Allows you to set the namspace prefix directly as and attribute
                    on the XPath expression element. If you set <code>ns-prefix</code>,
                    you must also set the <code>ns-uri</code> attribute.
                    <emphasis>Optional</emphasis>.
                </para>
            </callout>
            <callout arearefs="xpath-expression-xml05-co" id="xpath-expression-xml05">
                <para>
                    Allows you to set the namspace URI directly as an attribute
                    on the XPath expression element. If you set <code>ns-uri</code>,
                    you must also set the <code>ns-prefix</code> attribute.
                    <emphasis>Optional</emphasis>.
                </para>
            </callout>
            <callout arearefs="xpath-expression-xml06-co" id="xpath-expression-xml06">
                <para>
                    Defines a map containing namespaces. Only one map child element
                    is allowed. The key of the map  defines the namespace prefix
                    and the value of the map sets the namespace URI.
                </para>
                <para>
                    It is not valid to specify both this sub-element
                    and the <code>map</code> attribute, or setting the
                    <code>ns-prefix</code> and <code>ns-uri</code> attributes.
                    <emphasis>Optional</emphasis>.
                </para>
            </callout>
        </calloutlist>
    </para>
    <section>
        <title>Providing Namespaces (Optional) to XPath Expressions</title>
        <para>
	        For the XPath Expression Element, namespace information can be optionally
	        provided as configuration parameters. As such, namespaces can be defined
	        using one of the following 3 choices:
        </para>
        <itemizedlist>
            <listitem>Reference a map using the <code>namespace-map</code> attribute</listitem>
            <listitem>Provide a map of namespaces using the <code>map</code> sub-element</listitem>
            <listitem>Specifying the <code>ns-prefix</code> and the <code>ns-uri</code> attribute</listitem>
        </itemizedlist>
        <para>
            All three options are mutially exlusive. Only one option can be set.
        </para>
    </section>
    <para>
        Below, please find several different usage examples on how to use XPath
        expressions using the XML namespace support including the various option for
        setting the XML namespaces as discussed above.
    </para>
    <programlisting language="xml"><![CDATA[<int-xml:xpath-filter id="filterReferencingXPathExpression"
                      xpath-expression-ref="refToXpathExpression"/>

<int-xml:xpath-expression id="refToXpathExpression" expression="/name"/>

<int-xml:xpath-filter id="filterWithoutNamespace">
   <int-xml:xpath-expression expression="/name"/>
</int-xml:xpath-filter>

<int-xml:xpath-filter id="filterWithOneNamespace">
    <int-xml:xpath-expression expression="/ns1:name"
                              ns-prefix="ns1" ns-uri="www.example.org"/>
</int-xml:xpath-filter>

<int-xml:xpath-filter id="filterWithTwoNamespaces">
    <int-xml:xpath-expression expression="/ns1:name/ns2:type">
        <map>
            <entry key="ns1" value="www.example.org/one"/>
            <entry key="ns2" value="www.example.org/two"/>
        </map>
    </int-xml:xpath-expression>
</int-xml:xpath-filter>

<int-xml:xpath-filter id="filterWithNamespaceMapReference">
    <int-xml:xpath-expression expression="/ns1:name/ns2:type"
                              namespace-map="defaultNamespaces"/>
</int-xml:xpath-filter>

<util:map id="defaultNamespaces">
    <util:entry key="ns1" value="www.example.org/one"/>
    <util:entry key="ns2" value="www.example.org/two"/>
</util:map>]]></programlisting>

    </section>
  </section>
  <section id="xml-transformation">
    <title>Transforming XML Payloads</title>
    <section id="xml-transformation-beans">
      <title>Configuring Transformers as Beans</title>
	  <para>
	      This section will explain the workings of the following transformers
	      and how to configure them as <emphasis>beans</emphasis>:
	  </para>

      <itemizedlist>
        <listitem>
            <para><classname>UnmarshallingTransformer</classname></para>
        </listitem>
        <listitem>
            <para><classname>MarshallingTransformer</classname></para>
        </listitem>
        <listitem>
            <para><classname>XsltPayloadTransformer</classname></para>
        </listitem>
      </itemizedlist>

      <para>
      All of the provided XML transformers extend
      <classname>AbstractTransformer</classname> or <classname>AbstractPayloadTransformer</classname>
      and therefore implement <interfacename>Transformer</interfacename>.  When configuring XML
      transformers as beans in Spring Integration you would normally configure the transformer
      in conjunction with either a <classname>MessageTransformingChannelInterceptor</classname> or a
      <classname>MessageTransformingHandler</classname>.  This allows the transformer to be used as either an interceptor,
      which transforms the message as it is sent or received to the channel, or as an endpoint.  Finally the
      namespace support will be discussed which allows for the simple configuration of the transformers as
      elements in XML.
    </para>
    <para>
      <classname>UnmarshallingTransformer</classname> allows an XML <interfacename>Source</interfacename>
      to be unmarshalled using implementations of Spring OXM <interfacename>Unmarshaller</interfacename>.
      Spring OXM provides several implementations supporting marshalling and unmarshalling using JAXB,
      Castor and JiBX amongst others.  Since the unmarshaller requires an instance of
      <interfacename>Source</interfacename> where the message payload is not currently an instance of
      <interfacename>Source</interfacename>, conversion will be attempted.  Currently <classname>String</classname>
      and <interfacename>org.w3c.dom.Document</interfacename> payloads are supported.  Custom conversion to a
      <interfacename>Source</interfacename> is also supported by injecting an implementation of
      <interfacename>SourceFactory</interfacename>.
    </para>
    <para>
      <programlisting language="xml"><![CDATA[<bean id="unmarshallingTransformer"
      class="org.springframework.integration.xml.transformer.UnmarshallingTransformer">
    <constructor-arg>
        <bean class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
        <property name="contextPath" value="org.example" />
        </bean>
    </constructor-arg>
</bean>]]></programlisting>
    </para>
    <para>
      The <classname>MarshallingTransformer</classname> allows an object graph to be converted
      into XML using a Spring OXM <interfacename>Marshaller</interfacename>.  By default the
      <classname>MarshallingTransformer</classname> will return a <classname>DomResult</classname>.
      However the type of result can be controlled by configuring an alternative <interfacename>ResultFactory</interfacename>
      such as <classname>StringResultFactory</classname>.  In many cases it will be more convenient to transform
      the payload into an alternative XML format.  To achieve this configure a
      <interfacename>ResultTransformer</interfacename>.  Two implementations are provided, one which converts to
      <classname>String</classname> and another which converts to <interfacename>Document</interfacename>.
    </para>

      <programlisting language="xml"><![CDATA[<bean id="marshallingTransformer"
      class="org.springframework.integration.xml.transformer.MarshallingTransformer">
  <constructor-arg>
    <bean class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
      <property name="contextPath" value="org.example"/>
    </bean>
  </constructor-arg>
  <constructor-arg>
    <bean
      class="org.springframework.integration.xml.transformer.ResultToDocumentTransformer"/>
  </constructor-arg>
</bean>]]></programlisting>

    <para>
      By default, the <classname>MarshallingTransformer</classname> will pass the payload Object
      to the <interfacename>Marshaller</interfacename>, but if its boolean <code>extractPayload</code> property
      is set to <code>false</code>, the entire <interfacename>Message</interfacename> instance will be passed
      to the <interfacename>Marshaller</interfacename> instead. That may be useful for certain custom
      implementations of the <interfacename>Marshaller</interfacename> interface, but typically the
      payload is the appropriate source Object for marshalling when delegating to any of the various
      out-of-the-box <interfacename>Marshaller</interfacename> implementations.
    </para>
    <para>
      <classname>XsltPayloadTransformer</classname> transforms XML payloads using xsl.
      The transformer requires an instance of either <interfacename>Resource</interfacename> or
      <interfacename>Templates</interfacename>.  Passing in a <interfacename>Templates</interfacename> instance
      allows for greater configuration of the <interfacename>TransformerFactory</interfacename> used to create
      the template instance.  As in the case of <classname>XmlPayloadMarshallingTransformer</classname>
      by default <classname>XsltPayloadTransformer</classname> will create a message with a
      <interfacename>Result</interfacename> payload.  This can be customised by providing a
      <interfacename>ResultFactory</interfacename> and/or a <interfacename>ResultTransformer</interfacename>.
    </para>

    <programlisting language="xml"><![CDATA[<bean id="xsltPayloadTransformer"
      class="org.springframework.integration.xml.transformer.XsltPayloadTransformer">
  <constructor-arg value="classpath:org/example/xsl/transform.xsl"/>
  <constructor-arg>
    <bean
     class="org.springframework.integration.xml.transformer.ResultToDocumentTransformer"/>
  </constructor-arg>
</bean>]]></programlisting>

  </section>
	  <section id="xml-transformer-namespace">
	    <title>Namespace Support for XML Transformers</title>
	    <para>
	      Namespace support for all XML transformers is provided in the Spring Integration XML namespace,
	      a template for which can be seen below.  The namespace support for transformers creates an instance of either
	      <classname>EventDrivenConsumer</classname> or <classname>PollingConsumer</classname>
	      according to the type of the provided input channel.  The namespace support is designed
	      to reduce the amount of XML configuration by allowing the creation of an endpoint and transformer
	      using one element.
	    </para>
	    <para>
	    The namespace support for <classname>UnmarshallingTransformer</classname> is shown below.
	    Since the namespace is now creating an endpoint instance rather than a transformer,
	    a poller can also be nested within the element to control the polling of the input channel.
	    </para>
	    <programlisting language="xml"><![CDATA[<int-xml:unmarshalling-transformer id="defaultUnmarshaller"
    input-channel="input"
    output-channel="output"
    unmarshaller="unmarshaller"/>

<int-xml:unmarshalling-transformer id="unmarshallerWithPoller"
    input-channel="input"
    output-channel="output"
    unmarshaller="unmarshaller">
    <int:poller fixed-rate="2000"/>
<int-xml:unmarshalling-transformer/>]]></programlisting>

	    <para>
	    The namespace support for the marshalling transformer requires an <code>input-channel</code>, <code>output-channel</code> and a
	    reference to a <code>marshaller</code>.  The optional <code>result-type</code> attribute can be used to control the type of result created,
	    valid values are StringResult or DomResult (the default).  Where the provided result types are not sufficient a
	    reference to a custom implementation of <interfacename>ResultFactory</interfacename> can be provided as an alternative
	    to setting the <code>result-type</code> attribute using the <code>result-factory</code> attribute.  An optional <code>result-transformer</code> can also be
	    specified in order to convert the created <interfacename>Result</interfacename> after marshalling.
	    </para>

	    <programlisting language="xml"><![CDATA[<int-xml:marshalling-transformer
     input-channel="marshallingTransformerStringResultFactory"
     output-channel="output"
     marshaller="marshaller"
     result-type="StringResult" />

<int-xml:marshalling-transformer
    input-channel="marshallingTransformerWithResultTransformer"
    output-channel="output"
    marshaller="marshaller"
    result-transformer="resultTransformer" />

<bean id="resultTransformer"
      class="org.springframework.integration.xml.transformer.ResultToStringTransformer"/>]]></programlisting>

	  <para>
	    Namespace support for the <classname>XsltPayloadTransformer</classname> allows either a resource to be passed in in order to create the
	    <interfacename>Templates</interfacename> instance or alternatively a precreated <interfacename>Templates</interfacename>
	    instance can be passed in as a reference.  In common with the marshalling transformer the type of the result output can
	    be controlled by specifying either the result-factory or <code>result-type</code> attribute.  A <code>result-transfomer</code> attribute can also
	    be used to reference an implementation of <interfacename>ResultTransfomer</interfacename> where conversion of the result
	    is required before sending.
	  </para>
	  <programlisting language="xml"><![CDATA[<int-xml:xslt-transformer id="xsltTransformerWithResource"
    input-channel="withResourceIn"
    output-channel="output"
    xsl-resource="org/springframework/integration/xml/config/test.xsl"/>
<int-xml:xslt-transformer id="xsltTransformerWithTemplatesAndResultTransformer"
    input-channel="withTemplatesAndResultTransformerIn"
    output-channel="output"
    xsl-templates="templates"
    result-transformer="resultTransformer"/>]]></programlisting>

	    <para>
	    Very often to assist with transformation you may need to have access to Message data (e.g., Message Headers). For example; you may need to get access to certain Message Headers
	      and pass them on as parameters to a transformer (e.g., transformer.setParameter(..)). 
	        Spring Integration provides two convenient ways to accomplish this. Just look at the following XML snippet.
	<programlisting language="xml"><![CDATA[<int-xml:xslt-transformer id="paramHeadersCombo"
      input-channel="paramHeadersComboChannel"
    output-channel="output"
    xsl-resource="classpath:transformer.xslt"
    xslt-param-headers="testP*, *foo, bar, baz">

    <int-xml:xslt-param name="helloParameter" value="hello"/>
    <int-xml:xslt-param name="firstName" expression="headers.fname"/>
</int-xml:xslt-transformer>]]></programlisting>
	        If message header names match 1:1 to parameter names, you can simply use <code>xslt-param-headers</code> attribute. There you can also use wildcards for
	        simple pattern matching which supports the following simple pattern styles: "xxx*", "*xxx", "*xxx*" and "xxx*yyy".
	    </para>
	    <para>
	        You can also configure individual xslt parameters via &lt;xslt-param/&gt; sub element. There you can use <code>expression</code> or <code>value</code> attribute.
	        The <code>expression</code> attribute should be any valid SpEL expression with Message being the root object of the expression evaluation context.
	        The <code>value</code> attribute just like any <code>value</code> in Spring beans allows you to specify simple scalar vallue. YOu can also use property placeholders (e.g., ${some.value})
	        So as you can see, with the <code>expression</code> and <code>value</code> attribute xslt parameters could now be mapped to any accessible part of the Message as well as any literal value.
	    </para>
	  </section>
  </section>
  <section id="xml-xpath-transformer">
    <title>Transforming XML Messages Using XPath</title>
    <para>
      When it comes to message transformation XPath is a great way to transform Messages that have XML
      payloads by defining XPath transformers via &lt;xpath-transformer/&gt; element.
    </para>
    <para>
    <emphasis>Simple XPath transformation</emphasis>
    </para>
    <para>
    Let's look at the following transformer configuration:
    </para>
    <programlisting language="xml"><![CDATA[<int-xml:xpath-transformer input-channel="inputChannel" output-channel="outputChannel"
      xpath-expression="/person/@name" />]]></programlisting>
    <para>
    . . . and Message
    </para>
    <programlisting language="java"><![CDATA[Message<?> message =
  MessageBuilder.withPayload("<person name='John Doe' age='42' married='true'/>").build();]]></programlisting>
    <para>
    After sending this message to the 'inputChannel' the XPath transformer configured above will transform
    this XML Message to a simple Message with payload of 'John Doe' all based on
    the simple XPath Expression specified in the <code>xpath-expression</code> attribute.
    </para>
    <para>
    XPath also has the capability to perform simple conversion of extracted elements
    to a desired type. Valid return types are defined in <classname>javax.xml.xpath.XPathConstants</classname> and follows
    the conversion rules specified by the <interfacename>javax.xml.xpath.XPath</interfacename> interface.
    </para>
    <para>
    The following constants are defined by the <classname>XPathConstants</classname> class: <emphasis>BOOLEAN, DOM_OBJECT_MODEL, NODE, NODESET, NUMBER, STRING</emphasis>
    </para>
    <para>
    You can configure the desired type by simply using the <code>evaluation-type</code>
    attribute of the <code>&lt;xpath-transformer/&gt;</code> element.
    </para>
    <programlisting language="xml"><![CDATA[<int-xml:xpath-transformer input-channel="numberInput" xpath-expression="/person/@age"
                           evaluation-type="NUMBER_RESULT" output-channel="output"/>

<int-xml:xpath-transformer input-channel="booleanInput"
                           xpath-expression="/person/@married = 'true'"
                           evaluation-type="BOOLEAN_RESULT" output-channel="output"/>
]]></programlisting>

    <para>
    <emphasis>Node Mappers</emphasis>
    </para>
    <para>
    If you need to provide custom mapping for the node extracted by the XPath expression simply provide a reference to the
    implementation of the <classname>org.springframework.xml.xpath.NodeMapper</classname> - an interface used by
    <classname>XPathOperations</classname> implementations for mapping Node objects on a per-node basis. To provide a
    reference to a <classname>NodeMapper</classname> simply use <code>node-mapper</code> attribute:
    </para>
    <programlisting language="xml"><![CDATA[<int-xml:xpath-transformer input-channel="nodeMapperInput" xpath-expression="/person/@age"
                           node-mapper="testNodeMapper" output-channel="output"/>]]></programlisting>
    <para>
. . . and Sample NodeMapper implementation:
    </para>
<programlisting language="java"><![CDATA[class TestNodeMapper implements NodeMapper {
  public Object mapNode(Node node, int nodeNum) throws DOMException {
    return node.getTextContent() + "-mapped";
  }
}]]></programlisting>

    <para>
    <emphasis>XML Payload Converter</emphasis>
    </para>
    <para>
    You can also use an implementation of the <classname>org.springframework.integration.xml.XmlPayloadConverter</classname> to
    provide more granular transformation:
    </para>
    <programlisting language="xml"><![CDATA[<int-xml:xpath-transformer input-channel="customConverterInput"
                           output-channel="output" xpath-expression="/test/@type"
                           converter="testXmlPayloadConverter" />
]]></programlisting>

    <para>
. . . and Sample XmlPayloadConverter implementation:
    </para>
<programlisting language="java"><![CDATA[class TestXmlPayloadConverter implements XmlPayloadConverter {
  public Source convertToSource(Object object) {
    throw new UnsupportedOperationException();
  }
  //
  public Node convertToNode(Object object) {
    try {
      return DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(
          new InputSource(new StringReader("<test type='custom'/>")));
    }
    catch (Exception e) {
      throw new IllegalStateException(e);
    }
  }
  //
  public Document convertToDocument(Object object) {
    throw new UnsupportedOperationException();
  }
}]]></programlisting>

    <para>The DefaultXmlPayloadConverter is used if this reference is not provided, and it
    should be sufficient in most cases since it can convert from Node, Document, Source,
    File, and String typed payloads. If you need to extend beyond the capabilities of
    that default implementation, then an upstream Transformer is probably a better option
    than providing a reference to a custom implementation of this strategy here.</para>

  </section><section id="xml-xpath-splitting">
    <title>Splitting XML Messages</title>
    <para>
      <classname>XPathMessageSplitter</classname> supports messages with either
      <classname>String</classname> or <interfacename>Document</interfacename> payloads.
      The splitter uses the provided XPath expression to split the payload into a number of
      nodes.  By default this will result in each <interfacename>Node</interfacename> instance
      becoming the payload of a new message.  Where it is preferred that each message be a Document
      the <methodname>createDocuments</methodname> flag can be set.  Where a <classname>String</classname> payload is passed
      in the payload will be converted then split before being converted back to a number of String
      messages.  The XPath splitter implements <interfacename>MessageHandler</interfacename> and should
      therefore be configured in conjunction with an appropriate endpoint (see the namespace support below
      for a simpler configuration alternative).
    </para>
      <programlisting language="xml"><![CDATA[<bean id="splittingEndpoint"
      class="org.springframework.integration.endpoint.EventDrivenConsumer">
    <constructor-arg ref="orderChannel" />
    <constructor-arg>
        <bean class="org.springframework.integration.xml.splitter.XPathMessageSplitter">
            <constructor-arg value="/order/items" />
            <property name="documentBuilder" ref="customisedDocumentBuilder" />
            <property name="outputChannel" ref="orderItemsChannel" />
        </bean>
    </constructor-arg>
</bean>]]></programlisting>

    <para>
      XPath splitter namespace support allows the creation of a Message Endpoint with an input channel and output channel.
    </para>
    <programlisting language="xml"><![CDATA[<!-- Split the order into items creating a new message for each item node -->
<int-xml:xpath-splitter id="orderItemSplitter"
                       input-channel="orderChannel"
                       output-channel="orderItemsChannel">
    <int-xml:xpath-expression expression="/order/items"/>
</int-xml:xpath-splitter>

<!-- Split the order into items creating a new document for each item-->
<int-xml:xpath-splitter id="orderItemDocumentSplitter"
                       input-channel="orderChannel"
                       output-channel="orderItemsChannel"
                       create-documents="true">
    <int-xml:xpath-expression expression="/order/items"/>
    <int:poller fixed-rate="2000"/>
</int-xml:xpath-splitter>]]></programlisting>

  </section>

  <section id="xml-xpath-routing">
    <title id="xml-xpath-routing.title">Routing XML Messages Using XPath</title>
    <para>
      Similar to SpEL-based routers, Spring Integration provides support for routing messages based on XPath expressions,
      allowing you to create a Message Endpoint with an input channel but no output channel. Instead, one or more output
      channels are determined dynamically.
    </para>
    <programlisting language="xml"><![CDATA[<int-xml:xpath-router id="orderTypeRouter" input-channel="orderChannel">
    <si-xml:xpath-expression expression="/order/type"/>
</int-xml:xpath-router>]]></programlisting>

    <note>
       For an overview of attributes that are common among Routers, please see chapter:
       <emphasis><xref linkend='router-common-parameters' endterm="router-common-parameters.title"/></emphasis>
    </note>
    <para>
        Internally XPath expressions will be evaluated as <emphasis>NODESET</emphasis>
        type and converted to a <classname>List&lt;String&gt;</classname> representing
        channel names. Typically such a list will contain a single channel name.
        However, based on the results of an XPath Expression, the XPath router can
        also take on the characteristics of a <emphasis>Recipient List Router</emphasis>
        if the XPath Expression returns more then one value. In that case, the
        <classname>List&lt;String&gt;</classname> will contain more then one
        channel name and consequently Messages will be sent to all channels in the list.
    </para>
    <para>
        Thus, assuming that the XML file passed to the router configured below
        contains many <code>responder</code> sub-elements representing channel names,
        the message will be sent to all of those channels.
    </para>
    <programlisting language="xml"><![CDATA[<!-- route the order to all responders-->
<int-xml:xpath-router id="responderRouter" input-channel="orderChannel">
    <int-xml:xpath-expression expression="/request/responders"/>
</int-xml:xpath-router>
]]></programlisting>

    <para>
	    If the returned values do not represent the channel names directly, additional
	    mapping parameters can be specified, in order to map those returned values to actual
	    channel names. For example if the <code>/request/responders</code> expression
	    results in two values <code>responderA</code> and <code>responderB</code> but
	    you don't want to couple the responder names to channel names, you may provide
	    additional mapping configuration such as the following:
    </para>
    <programlisting language="xml"><![CDATA[<!-- route the order to all responders-->
<int-xml:xpath-router id="responderRouter" input-channel="orderChannel">
    <int-xml:xpath-expression expression="/request/responders"/>
    <int-xml:mapping value="responderA" channel="channelA"/>
    <int-xml:mapping value="responderB" channel="channelB"/>
</int-xml:xpath-router>
]]></programlisting>

    <para>
	    As already mentioned, the default evaluation type for XPath expressions is
	    <emphasis>NODESET</emphasis>, which is converted to a
	    <code>List&lt;String&gt;</code> of channel names, therefore handling
	    single channel scenarios as well as multiple ones.
    </para>
    <para>
	    Nonetheless, certain XPath expressions may evaluate as String type from the
	    very beginning. Take for example the following XPath Expression:
	</para>
    <programlisting language="xml"><![CDATA[name(./node())]]></programlisting>
	<para>
	    This expression will return the name of the root node. It will resulting
	    in an exception, if the default evaluation type <emphasis>NODESET</emphasis>
	    is being used.
	</para>
	<para>
	    For these scenarious, you may use the <code>evaluate-as-string</code> attribute,
	    which will allow you to manage the evaluation type. It is <code>FALSE</code>
	    by default, however if set to <code>TRUE</code>, the String evaluation
	    type will be used.
	</para>
    <note>
        <para>
            To provide some background information: XPath 1.0 specifies 4 data types:
        </para>
        <itemizedlist>
            <listitem>Node-sets</listitem>
            <listitem>Strings</listitem>
            <listitem>Number</listitem>
            <listitem>Boolean</listitem>
        </itemizedlist>
        <para>
            When the XPath Router evaluates expressions using the optional
            <code>evaluate-as-string</code> attribute, the return value is
            determined per the <code>string()</code> function as defined in the
            XPath specification. This means that if the expression selects
            multiple nodes, it will return the string value of the first node.
        </para>
        <para>
            For further information, please see:
        </para>
       <itemizedlist>
           <listitem>Specification: XML Path Language (XPath) Version 1.0: http://www.w3.org/TR/xpath/</listitem>
           <listitem>XPath specification - string() function: http://www.w3.org/TR/xpath/#function-string</listitem>
       </itemizedlist>
    </note>
	<para>
	    For example if we want to route based on the name of the root node, we
	    can use the following configuration:
    </para>
    <programlisting language="xml"><![CDATA[<int-xml:xpath-router id="xpathRouterAsString"
        input-channel="xpathStringChannel"
        evaluate-as-string="true">
    <int-xml:xpath-expression expression="name(./node())"/>
</int-xml:xpath-router>
]]></programlisting>
    <section id="xpath-routing-converter">
	    <title>XML Payload Converter</title>
	    <para>
		    For XPath Routers, you can also specify the Converter to use when converting
		    payloads prior to XPath evaluation. As such, the XPath Router supports
		    custom implementations of the <classname>XmlPayloadConverter</classname> strategy,
		    and when configuring an <code>xpath-router</code> element in XML, a reference
		    to such an implementation may be provided via the <code>converter</code> attribute.
		</para>
		<para>
		    If this reference is not explicitly provided, the <classname>DefaultXmlPayloadConverter</classname>
		    is used. It should be sufficient in most cases, since it can convert from
		    Node, Document, Source, File, and String typed payloads. If you need to
		    extend beyond the capabilities of that default implementation, then an
		    upstream Transformer is generally a better option in most cases, rather
		    than providing a reference to a custom implementation of this strategy here.
	    </para>
    </section>
  </section>
  <section id="xml-xpath-header-enricher">
    <title>XPath Header Enricher</title>
    <para>
        The XPath Header Enricher defines a Header Enricher Message Transformer
        that evaluates XPath expressions against the message payload and inserts
        the result of the evaluation into a messsage header.
    </para>
    <para>
        Please see below for an overview of all available configuration parameters:
    </para>
    <programlisting language="xml"><![CDATA[<int-xml:xpath-header-enricher default-overwrite="true"   ]]><co id="xpath-header-enricher-xml01-co" linkends="xpath-header-enricher-xml01" /><![CDATA[
	                           id=""                      ]]><co id="xpath-header-enricher-xml02-co" linkends="xpath-header-enricher-xml02" /><![CDATA[
	                           input-channel=""           ]]><co id="xpath-header-enricher-xml03-co" linkends="xpath-header-enricher-xml03" /><![CDATA[
	                           output-channel=""          ]]><co id="xpath-header-enricher-xml04-co" linkends="xpath-header-enricher-xml04" /><![CDATA[
	                           should-skip-nulls="true">  ]]><co id="xpath-header-enricher-xml05-co" linkends="xpath-header-enricher-xml05" /><![CDATA[
    <int:poller></int:poller>                             ]]><co id="xpath-header-enricher-xml06-co" linkends="xpath-header-enricher-xml06" /><![CDATA[
    <int-xml:header name=""                               ]]><co id="xpath-header-enricher-xml07-co" linkends="xpath-header-enricher-xml07" /><![CDATA[
                    evaluation-type="STRING_RESULT"       ]]><co id="xpath-header-enricher-xml08-co" linkends="xpath-header-enricher-xml08" /><![CDATA[
                    overwrite="true"                      ]]><co id="xpath-header-enricher-xml09-co" linkends="xpath-header-enricher-xml09" /><![CDATA[
                    xpath-expression=""                   ]]><co id="xpath-header-enricher-xml10-co" linkends="xpath-header-enricher-xml10" /><![CDATA[
                    xpath-expression-ref=""/>             ]]><co id="xpath-header-enricher-xml11-co" linkends="xpath-header-enricher-xml11" /><![CDATA[
</int-xml:xpath-header-enricher>]]>
    </programlisting>
    <para>
	    <calloutlist>
	        <callout arearefs="xpath-header-enricher-xml01-co" id="xpath-header-enricher-xml01">
	            <para>
	                Specify the default boolean value for whether to overwrite existing
	                header values. This will only take effect for sub-elements that
	                do not provide their own 'overwrite' attribute. If the 'default-
					overwrite' attribute is not provided, then the specified header
					values will NOT overwrite any existing ones with the same header names.
	                <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-header-enricher-xml02-co" id="xpath-header-enricher-xml02">
	            <para>
	                Id for the underlying bean definition.
	                <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-header-enricher-xml03-co" id="xpath-header-enricher-xml03">
	            <para>The receiving Message channel of this endpoint. <emphasis>Optional</emphasis>.</para>
	        </callout>
	        <callout arearefs="xpath-header-enricher-xml04-co" id="xpath-header-enricher-xml04">
                    Channel to which enriched messages shall be send to. <emphasis>Optional</emphasis>.
	        </callout>
	        <callout arearefs="xpath-header-enricher-xml05-co" id="xpath-header-enricher-xml05">
	            <para>
					Specify whether null values, such as might be returned from
					an expression evaluation, should be skipped. The default value
					is true. Set this to false if a null value should trigger removal of the
					corresponding header instead.
	                <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-header-enricher-xml06-co" id="xpath-header-enricher-xml06">
	            <para>
	                <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-header-enricher-xml07-co" id="xpath-header-enricher-xml07">
	            <para>
	                The name of the header to be enriched.
	                <emphasis>Mandatory</emphasis>.
	             </para>
	        </callout>
	        <callout arearefs="xpath-header-enricher-xml08-co" id="xpath-header-enricher-xml08">
	            <para>
	                The result type expected from the XPath evaluation. This will be the type of the header value.
	                The following values are allowed: BOOLEAN_RESULT, STRING_RESULT, NUMBER_RESULT, NODE_RESULT and NODE_LIST_RESULT.
	                Defaults internally to <code>XPathEvaluationType.STRING_RESULT</code> if not set. <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-header-enricher-xml09-co" id="xpath-header-enricher-xml09">
	            <para>
	                Boolean value to indicate whether this header value should overwrite an existing header value for
                    the same name if already present on the input Message.
	            </para>
	        </callout>
            <callout arearefs="xpath-header-enricher-xml10-co" id="xpath-header-enricher-xml10">
                <para>
                    The XPath Expression as a String. Either this attribute or
                    <code>xpath-expression-ref</code> must be provided, but not both.
                </para>
            </callout>
            <callout arearefs="xpath-header-enricher-xml11-co" id="xpath-header-enricher-xml11">
                <para>
                    The XPath Expression reference. Either this attribute or
                    <code>xpath-expression</code> must be provided, but not both.
                </para>
            </callout>
	    </calloutlist>
	</para>
  </section>
  <section id="xml-xpath-filter">
    <title>Using the XPath Filter</title>
    <para>
	    This component defines an XPath-based Message Filter. Under the covers this
	    components uses a <code>MessageFilter</code> that wraps an instance
	    of <code>AbstractXPathMessageSelector</code>.
	</para>
	<note>
	    Please also refer to the chapter on <link linkend='filter'>
	    Message Filters</link> for further details.
	</note>
	<para>
	    In order to use the XPath Filter you must as a minimum provide an XPath
	    Expression either by declaring the <code>xpath-expression</code> sub-element
	    or by referencing an XPath Expression using the <code>xpath-expression-ref</code>
	    attribute.
    </para>
    <para>
	    If the provided XPath expression will evaluate to a <code>boolean</code>
	    value, no further configuration parameters are necessary. However, if
	    the XPath expression will evaluate to a String, the <code>match-value</code>
	    attribute should be specified against which the evaluation result will
	    be matched.
	</para>
	<para>
	    There are three options for the <code>match-type</code>:
	</para>
	<itemizedlist>
	    <listitem>
	        <emphasis role="bold">exact</emphasis> - correspond to <code>equals</code> on <code>java.lang.String</code>.
	        The underlying implementation uses a <code>StringValueTestXPathMessageSelector</code>
	    </listitem>
	    <listitem>
	        <emphasis role="bold">case-insensitive</emphasis> - correspond to <code>equals-ignore-case</code> on <code>java.lang.String</code>.
	        The underlying implementation uses a <code>StringValueTestXPathMessageSelector</code>
	    </listitem>
	    <listitem>
	        <emphasis role="bold">regex</emphasis> - matches operations one <code>java.lang.String</code>.
	        The underlying implementation uses a <code>RegexTestXPathMessageSelector</code>
	    </listitem>
	</itemizedlist>
	<para>
	    When providing a 'match-type' value of 'regex', the value provided with
	    thos <code>match-value</code> attribute must be a valid Regular Expression.
    </para>

    <note>
        In prior versions of Spring Integration the functionality of the XPath Filter
        was configured using the <code>xpath-selector</code> element. However, in order
        to provide a more consistent behavior within the Spring Integration Framework,
        <emphasis role="bold">the <code>xpath-selector</code> element is deprecated as of version 2.1</emphasis>.

        Please use <code>&lt;xpath-filter&gt;</code> instead. It provides the same
        set of functionality. In fact it still uses the same <code>MessageSelectors</code>
        internally.
    </note>

	<programlisting language="xml"><![CDATA[<int-xml:xpath-filter discard-channel=""                     ]]><co id="xpath-filter-xml01-co" linkends="xpath-filter-xml01" /><![CDATA[
                      id=""                                  ]]><co id="xpath-filter-xml02-co" linkends="xpath-filter-xml02" /><![CDATA[
                      input-channel=""                       ]]><co id="xpath-filter-xml03-co" linkends="xpath-filter-xml03" /><![CDATA[
                      match-type="exact"                     ]]><co id="xpath-filter-xml04-co" linkends="xpath-filter-xml04" /><![CDATA[
                      match-value=""                         ]]><co id="xpath-filter-xml05-co" linkends="xpath-filter-xml05" /><![CDATA[
                      output-channel=""                      ]]><co id="xpath-filter-xml06-co" linkends="xpath-filter-xml06" /><![CDATA[
                      throw-exception-on-rejection="false"   ]]><co id="xpath-filter-xml07-co" linkends="xpath-filter-xml07" /><![CDATA[
                      xpath-expression-ref="">               ]]><co id="xpath-filter-xml08-co" linkends="xpath-filter-xml08" /><![CDATA[
    <int-xml:xpath-expression ... />                         ]]><co id="xpath-filter-xml09-co" linkends="xpath-filter-xml09" /><![CDATA[
    <int:poller ... />                                       ]]><co id="xpath-filter-xml10-co" linkends="xpath-filter-xml10" /><![CDATA[
</int-xml:xpath-filter>]]></programlisting>
    <para>
	<calloutlist>
	    <callout arearefs="xpath-filter-xml01-co" id="xpath-filter-xml01">
	        <para>
	            Message Channel where you want rejected messages to be sent.
	            <emphasis>Optional</emphasis>.
	        </para>
	    </callout>
	    <callout arearefs="xpath-filter-xml02-co" id="xpath-filter-xml02">
	        <para>
	            Id for the underlying bean definition.
	            <emphasis>Optional</emphasis>.
	        </para>
	    </callout>
	    <callout arearefs="xpath-filter-xml03-co" id="xpath-filter-xml03">
	        <para>The receiving Message channel of this endpoint. <emphasis>Optional</emphasis>.</para>
	    </callout>
	    <callout arearefs="xpath-filter-xml04-co" id="xpath-filter-xml04">
	        <para>
	            Type of match to apply between the XPath evaluation result and
	            the <emphasis>match-value</emphasis>.
                Default is <emphasis>exact</emphasis>. <emphasis>Optional</emphasis>.</para>
	    </callout>
	    <callout arearefs="xpath-filter-xml05-co" id="xpath-filter-xml05">
	        <para>
	            String value to be matched against the XPath evaluation result.
	            If this attribute is not provided, then the XPath evaluation
	            MUST produce a boolean result directly.
                <emphasis>Optional</emphasis>.
            </para>
	    </callout>
	    <callout arearefs="xpath-filter-xml06-co" id="xpath-filter-xml06">
	        <para>
	            The channel to which Messages that matched the filter criterias
	            shall be dispatched to. <emphasis>Optional</emphasis>.
	        </para>
	    </callout>
	    <callout arearefs="xpath-filter-xml07-co" id="xpath-filter-xml07">
	        <para>
	             By default, this property is set to <emphasis>false</emphasis>
	             and rejected Messages (Messages that did not match the filter
	             criteria) will be silently dropped. However, if set to
	             <emphasis>true</emphasis> message rejection will result in an
	             error condition and the exception will be propagated upstream
	             to the caller.
	             <emphasis>Optional</emphasis>.
	         </para>
	    </callout>
	    <callout arearefs="xpath-filter-xml08-co" id="xpath-filter-xml08">
	        <para>Reference to an XPath expression instance to evaluate.</para>
	    </callout>
	    <callout arearefs="xpath-filter-xml09-co" id="xpath-filter-xml09">
	        <para>
	            This sub-element sets the XPath expression to be evaluated. If
	            this is not defined you MUST define the <code> xpath-expression-ref</code>
	            attribute. Also, only one <code>xpath-expression</code> element
	            can be set.
	        </para>
	    </callout>
        <callout arearefs="xpath-filter-xml10-co" id="xpath-filter-xml10">
            <para>
                <emphasis>Optional</emphasis>.
            </para>
        </callout>
	</calloutlist></para>
  </section>

  <section id="xml-validating-filter">
    <title>XML Validating Filter</title>
    <para>
        The XML Validating Filter allows you to validate incoming messages against
        provided schema instances. The following schema types are supported:
    </para>

    <itemizedlist>
        <listitem>xml-schema (http://www.w3.org/2001/XMLSchema)</listitem>
        <listitem>relax-ng (http://relaxng.org/ns/structure/1.0)</listitem>
    </itemizedlist>

    <para>
        Messages that fail validation can either be
        silently dropped or they can be forwarded to a definable <code>discard-channel</code>.
        Furthermore you can configure this filter to throw an <code>Exception</code>
        in case validation fails.
    </para>
    <para>
        Please see below for an overview of all available configuration parameters:
    </para>
    <programlisting language="xml"><![CDATA[<int-xml:validating-filter discard-channel=""                   ]]><co id="xpath-validating-filter-xml01-co" linkends="xpath-validating-filter-xml01" /><![CDATA[
                           id=""                                ]]><co id="xpath-validating-filter-xml02-co" linkends="xpath-validating-filter-xml02" /><![CDATA[
                           input-channel=""                     ]]><co id="xpath-validating-filter-xml03-co" linkends="xpath-validating-filter-xml03" /><![CDATA[
                           output-channel=""                    ]]><co id="xpath-validating-filter-xml04-co" linkends="xpath-validating-filter-xml04" /><![CDATA[
                           schema-location=""                   ]]><co id="xpath-validating-filter-xml05-co" linkends="xpath-validating-filter-xml05" /><![CDATA[
                           schema-type="xml-schema"             ]]><co id="xpath-validating-filter-xml06-co" linkends="xpath-validating-filter-xml06" /><![CDATA[
                           throw-exception-on-rejection="false" ]]><co id="xpath-validating-filter-xml07-co" linkends="xpath-validating-filter-xml07" /><![CDATA[
                           xml-validator="">                    ]]><co id="xpath-validating-filter-xml08-co" linkends="xpath-validating-filter-xml08" /><![CDATA[
    <int:poller .../>                                           ]]><co id="xpath-validating-filter-xml09-co" linkends="xpath-validating-filter-xml09" /><![CDATA[
</int-xml:validating-filter>]]></programlisting>
    <para>
        <calloutlist>
	        <callout arearefs="xpath-validating-filter-xml01-co" id="xpath-validating-filter-xml01">
	            <para>
	                Message Channel where you want rejected messages to be sent.
	                <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-validating-filter-xml02-co" id="xpath-validating-filter-xml02">
	            <para>
	                Id for the underlying bean definition.
	                <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-validating-filter-xml03-co" id="xpath-validating-filter-xml03">
	            <para>The receiving Message channel of this endpoint. <emphasis>Optional</emphasis>.</para>
	        </callout>
	        <callout arearefs="xpath-validating-filter-xml04-co" id="xpath-validating-filter-xml04">
	            <para>
	                Message Channel where you want accepted messages to be sent. <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-validating-filter-xml05-co" id="xpath-validating-filter-xml05">
	            <para>
	                Sets the location of the schema to validate the Message's payload against. Internally
	                uses the <interfacename>org.springframework.core.io.Resource</interfacename> interface.
	                You can set this attribute or the <code>xml-validator</code> attribute but not both.
	                <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-validating-filter-xml06-co" id="xpath-validating-filter-xml06">
	            <para>
	                Sets the schema type. Can be either <code>xml-schema</code> or <code>relax-ng</code>.
	                <emphasis>Optional</emphasis>. If not set it defaults
	                to <code>xml-schema</code> which internally translates to
	                <classname>org.springframework.xml.validation.XmlValidatorFactory#SCHEMA_W3C_XML</classname>
	            </para>
	        </callout>
	        <callout arearefs="xpath-validating-filter-xml07-co" id="xpath-validating-filter-xml07">
	            <para>
	                If <code>true</code> a <classname>MessageRejectedException</classname> is thrown
	                in case validation fails for the provided Message's payload.
	                 <emphasis>Optional</emphasis>. Defaults to <code>false</code> if not set.
	             </para>
	        </callout>
	        <callout arearefs="xpath-validating-filter-xml08-co" id="xpath-validating-filter-xml08">
	            <para>
	                Reference to a custom <interfacename>sorg.springframework.xml.validation.XmlValidator</interfacename> strategy.
	                You can set this attribute or the <code>schema-location</code> attribute but not both.
	                <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
	        <callout arearefs="xpath-validating-filter-xml09-co" id="xpath-validating-filter-xml09">
	            <para>
	                <emphasis>Optional</emphasis>.
	            </para>
	        </callout>
        </calloutlist>
    </para>

  </section>

</chapter>
