SOASuite 11g- Implement User-Defined XPath Extension Functions

I had previously written a blog on creating XPATH function in 10g. This write up is on how to achieve the same in 11g.

In 11g the major difference is that XPATH functions has been extended to some more components.

· BPEL

· Mediator

· Human workflow

· XSLT Mapper

The implementation is different only for XSLT mapping. For all other components implementation is same. Functions can be shared across all components and is defined by the xpath-functions-config xml file.

For each component we will define functions in a component specific config file

BPEL - ext-bpel-xpath-functions-config.xml

Mediator - ext-mediator-xpath-functions-config.xml

XSLT Mapper - ext-mapper-xpath-functions-config.xml

Common to all - ext-soa-xpath-functions-config.xml

I will explain the steps involved to create user-defined Xpath function for both BPEL and XSL mapper.

BPEL

For creating user-defined XPATH function, we need to define a java component and a xml component .The Xml component will take care of the configuration where as java component will be the implementation of the function.

We will start with xml component. We will define the function interface in a xml format.

1. Create an xml file - ext-bpel-xpath-functions-config.xml

Add this xml snippet

<soa-xpath-functions version="11.1.1"

xmlns="http://xmlns.oracle.com/soa/config/xpath"

xmlns:geo="http://www.geo-functions.com/HelloWorld">

<function name="geo:helloWorld">

<className>com.geo.xpath.HelloWorldTest</className>

<return type="string"/>

<params>

<param name="value" type="string"/>

</params>

<desc/>

<detail>

<![CDATA[This function returns a HelloWorld message.]]>

</detail>

</function>

</soa-xpath-functions>

here function signature is helloWorld() ,The namespace of the function is xmlns:geo=http://www.geo-functions.com/HelloWorld

2. Create a simple java class to implement the XPATH BPEL function.

The java class should implement oracle.fabric.common.xml.xpath.IXPathFunction interface. You can find this class and related xpath functions in fabric-runtime.jar

Code Snippet HelloWorldTest.java

package com.geo.xpath;

import oracle.fabric.common.xml.xpath.IXPathFunction;

import oracle.fabric.common.xml.xpath.IXPathContext;

import oracle.fabric.common.xml.xpath.XPathFunctionException;

import java.util.List;

public class HelloWorldTest implements IXPathFunction {

public Object call(IXPathContext context, List args) throws XPathFunctionException {

return "Hello world :: "+args.get(0);

}

}

You need to have fabric-runtime.jar in your classpath for compiling this java class.

>javac -classpath lib\ fabric-runtime.jar -d classes com\geo\xpath\HelloWorldTest.java

Here lib points to the location of these jars. –d classes points to the output folder where I will get my class file.

3. Create a jar with the generated class file.

>jar -cvf helloWorld.jar com/geo/xpath/HelloWorldTest.class

The jar will not be complete without the configuration file. Now add the ext-bpel-xpath-functions-config.xml file to the META-INF folder

Development of custom XPATH function is done. Now we will use it.

Usage

In the BPEL process use an assign operation to invoke the function

Code Snippet of .bpel file

<assign name="Assign_1">

<copy>

<from expression="geo:helloWorld(string(bpws:getVariableData('inputVariable','payload','/client:process/client:input')))"/>

<to variable="Invoke_1_execute_InputVariable" part="request"

query="/ns3:singleString/ns3:input"/>

</copy>

</assign>

When you compile the bpel process you will get a compilation error because the namespace-prefix and namespace-uri are not declared in the bpel process. Add the namespace- prefix and namespace-uri from your new function defined in ext-bpel-xpath-functions-config.xml to the process tag of .bpel file

Code Snippet of .bpel file

<process name="XpathBpel" targetNamespace="http://xmlns.oracle.com/XpathBpel"

……….

……. xmlns:geo="http://www.geo-functions.com/HelloWorld"

>

Compile and deploy your bpel process. The output will be the return string of the call method defined in the function.

Runtime usage:

1. Copy the HelloWorld function jar to MIDDLEWARE_Home/user_projects/domains/soa_domain/lib or a subdirectory of lib.

2. Restart the Oracle WebLogic Server.

XSLT Mapper

As we did for BPEL, we need to define a java component and a xml component .The Xml component will take care of the configuration where as java component will be the implementation of the function.

We will start with xml component. We will define the function interface in an xml format.

1. Create an xml file - ext-mapper-xpath-functions-config.xml

Add this xml snippet

<soa-xpath-functions version="11.1.1"

xmlns="http://xmlns.oracle.com/soa/config/xpath"

xmlns:geo="http://www.oracle.com/XSL/Transform/java/com.geo.xpath.HelloWorldXSLTest">

<function name="geo:helloWorldXSL">

<className>com.geo.xpath.HelloWorldXSLTest</className>

<return type="string"/>

<params>

<param name="value" type="string"/>

</params>

<desc/>

<detail>

<![CDATA[This function returns a HelloWorld message.]]>

</detail>

</function>

</soa-xpath-functions>

Here function signature is helloWorldXSL() ,The namespace of the function is xmlns:geo= http://www.oracle.com/XSL/Transform/java/com.geo.xpath.HelloWorldXSLTest". The difference with BPEL XPATH function is the namespace. Here the namespace should be in a specific format. http://www.oracle.com/XSL/Transform/java/ + package name +Class name

2. Create a simple java class to implement the XPATH BPEL function. A point to note is that for each function you need to write a corresponding public static method. The function name and method name must match.

Code Snippet HelloWorldXSLTest.java

package com.geo.xpath;

public class HelloWorldXSLTest {

public static String helloWorldXSL(String input){

return "Hello worldXSL :: "+input;

}

}

Compile this java class.

>javac -d classes com\geo\xpath\HelloWorldXSLTest.java

3. Create a jar with the generated class file.

>jar -cvf helloWorldXSL.jar com/geo/xpath/HelloWorldXSLTest.class

The jar will not be complete without the configuration file. Now add the ext-mapper-xpath-functions-config.xml file to the META-INF folder

Development of custom XSL Mapper XPATH function is done. Now we will use it.

Usage

JDeveloper will support user defined XSL functions .To use it from the wizard

· In Oracle JDeveloper, go to Tools > Preferences > SOA.

· Click the Add button and select your JAR file.

· Restart Oracle JDeveloper for the changes to take effect.

The function will be listed in the user-defined functions under Component Palette. You can directly drag and drop into your XSL.

Code Snippet of .xsl file

<xsl:stylesheet version="1.0"

xmlns:geo="http://www.oracle.com/XSL/Transform/java/com.geo.xpath.HelloWorldXSLTest"

…………

…………..

>

<xsl:template match="/">

<client:processResponse>

<client:result>

<xsl:value-of select="geo:helloWorldXSL(/client:process/client:input)"/>

</client:result>

</client:processResponse>

</xsl:template>

</xsl:stylesheet>

Compile and deploy your bpel/mediator process having your XSL mapping file. The output will be the return string of the method defined in the function.

Runtime usage:

1. Copy the HelloWorldXSL function jar to MIDDLEWARE_Home/user_projects/domains/soa_domain/lib or a subdirectory of lib.

2. Restart the Oracle WebLogic Server.

That’s it J