Chapter 22. JXPath

The JXPath language enables you to invoke Java beans using the Apache Commons JXPath language. The JXPath language has a similar syntax to XPath, but instead of selecting element or attribute nodes from an XML document, it invokes methods on an object graph of Java beans. If one of the bean attributes returns an XML document (a DOM/JDOM instance), however, the remaining portion of the path is interpreted as an XPath expression and is used to extract an XML node from the document. In other words, the JXPath language provides a hybrid of object graph navigation and XML node selection.

To use JXPath in your routes you need to add a dependency on camel-jxpath to your project as shown in Example 22.1, “Adding the camel-jxpath dependency”.

<!-- Maven POM File -->
<properties>
  <camel-version>2.21.0.fuse-000077-redhat-1</camel-version>
  ...
</properties>

<dependencies>
  ...
  <dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-jxpath</artifactId>
    <version>${camel-version}</version>
  </dependency>
  ...
</dependencies>

<!-- Maven POM File -->
<properties>
  <camel-version>2.21.0.fuse-000077-redhat-1</camel-version>
  ...
</properties>

<dependencies>
  ...
  <dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-jxpath</artifactId>
    <version>${camel-version}</version>
  </dependency>
  ...
</dependencies>

Table 22.1, “JXPath variables” lists the variables that are accessible when using JXPath.

Table 22.2, “JXPath option” describes the option for JXPath.

The following example route uses JXPath:

<camelContext>
  <route>
    <from uri="activemq:MyQueue"/>
    <filter>
      <jxpath>in/body/name = 'James'</xpath>
      <to uri="mqseries:SomeOtherQueue"/>
    </filter>
  </route>
</camelContext>

<camelContext>
  <route>
    <from uri="activemq:MyQueue"/>
    <filter>
      <jxpath>in/body/name = 'James'</xpath>
      <to uri="mqseries:SomeOtherQueue"/>
    </filter>
  </route>
</camelContext>

The following simple example uses a JXPath expression as a predicate in a Message Filter:

{snippet:id=example|lang=java|url=camel/trunk/components/camel-jxpath/src/test/java/org/apache/camel/language/jxpath/JXPathFilterTest.java}

{snippet:id=example|lang=java|url=camel/trunk/components/camel-jxpath/src/test/java/org/apache/camel/language/jxpath/JXPathFilterTest.java}

You can use Bean Integration to invoke a method on a bean and use various languages, such as JXPath, to extract a value from the message and bind it to a method parameter.

For example:

public class Foo {
     @MessageDriven(uri = "activemq:my.queue")
     public void doSomething(@JXPath("in/body/foo") String correlationID, @Body String body)
     { // process the inbound message here }
   }

public class Foo {
     @MessageDriven(uri = "activemq:my.queue")
     public void doSomething(@JXPath("in/body/foo") String correlationID, @Body String body)
     { // process the inbound message here }
   }

Available as of Camel 2.11

You can externalize the script and have Camel load it from a resource such as "classpath:", "file:", or "http:". Use the following syntax:

"resource:scheme:location"

"resource:scheme:location"

For example, to reference a file on the classpath:

.setHeader("myHeader").jxpath("resource:classpath:myjxpath.txt")

.setHeader("myHeader").jxpath("resource:classpath:myjxpath.txt")