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h2. XQuery

Camel supports [XQuery|http://www.w3.org/TR/xquery/] to allow an [Expression] or [Predicate] to be used in the [DSL] or [Xml Configuration]. For example you could use XQuery to create an [Predicate] in a [Message Filter] or as an [Expression] for a [Recipient List].

h3. Options
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|| Name || Default Value || Description ||
| {{allowStAX}} | {{false}} | *Camel 2.8.3/2.9:* Whether to allow using StAX as the {{javax.xml.transform.Source}}. |
{div}

h3. Examples

{code}

from("queue:foo").filter().
  xquery("//foo").
  to("queue:bar")
{code}

{code}

h3. Variables

The IN message body will be set as the {{contextItem}}. Besides this these Variables is also added as parameters:

|| Variable || Type || Description ||
| exchange | Exchange | The current Exchange |
| in.body | Object | The In message's body  |
| out.body | Object | The OUT message's body (if any)|
| in.headers.*| Object | You can access the value of exchange.in.headers with key *foo* by using the variable which name is in.headers.foo|
| out.headers.* | Object | You can access the value of exchange.out.headers with key *foo* by using the variable which name is out.headers.foo variable|
| *key name* | Object | Any exchange.properties and exchange.in.headers and any additional parameters set using {{setParameters(Map)}}. These parameters is added with they own key name, for instance if there is an IN header with the key name *foo* then its added as *foo*. |

h3. Using XML configuration

If you prefer to configure your routes in your [Spring] XML file then you can use XPath expressions as follows

{code:lang=xml}
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:foo="http://example.com/person"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd">

  <camelContext id="camel" xmlns="http://activemq.apache.org/camel/schema/spring">
    <route>
      <from uri="activemq:MyQueue"/>
      <filter>
        <xquery>/foo:person[@name='James']</xquery>
        <to uri="mqseries:SomeOtherQueue"/>
      </filter>
    </route>
  </camelContext>
</beans>
{code}

 

{code:lang=xml}
    <xquery type="java.lang.String">concat('mock:foo.', /person/@city)</xquery>

{code}

h3. Using XQuery as an endpoint

Sometimes an XQuery expression can be quite large; it can essentally be used for [Templating]. So you may want to use an [XQuery Endpoint] so you can route using XQuery templates.

The following example shows how to take a message of an ActiveMQ queue (MyQueue) and transform it using XQuery and send it to MQSeries.

{code}
  <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
    <route>
      <from uri="activemq:MyQueue"/>
      <to uri="xquery:com/acme/someTransform.xquery"/>
      <to uri="mqseries:SomeOtherQueue"/>
    </route>
  </camelContext>
{code}

h3. Examples

Here is a simple [example|http://svn.apache.org/repos/asf/camel/trunk/components/camel-saxon/src/test/java/org/apache/camel/builder/saxon/XQueryFilterTest.java] using an XQuery expression as a predicate in a [Message Filter]

{snippet:id=example|lang=java|url=camel/trunk/components/camel-saxon/src/test/java/org/apache/camel/builder/saxon/XQueryFilterTest.java}

 Filter]

{snippet:id=example|lang=java|url=camel/trunk/components/camel-saxon/src/test/java/org/apache/camel/builder/saxon/XQueryWithNamespacesFilterTest.java}

h3. 

{code}

h3. Dependencies

To use XQuery in your camel routes you need to add the a dependency on *camel-saxon* which implements the XQuery language. 

If you use maven you could just add the following to your pom.xml, substituting the version number for the latest & greatest release (see [the download page for the latest versions|Download]).

{code}
<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-saxon</artifactId>
  <version>x.x.x</version>
</dependency>
{code}