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Oracle® Fusion Middleware Developer's Guide for Oracle Application Integration Architecture Foundation Pack
11g Release 1 (

Part Number E17364-11
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11 Developing and Deploying Custom XPath Functions

This chapter discusses how to implement a function in Java as a Java XPath Class, deploy an XPath/XSL function in JDeveloper and deploy an XPath/XSL function in application servers.

This chapter includes the following sections:

11.1 Implementing a Function in Java as a Java XPath Class

Since the custom function can be invoked either as an XPath or XSL function, the implementation class must take care of both. For this reason, the hosting class must have at least:

11.1.1 Naming Standards for Custom XPath Functions

These naming standards are enforced:

  • Function name

  • Function implementation class

  • Function implementation method

  • Function inner class

  • Function namespace

  • Function namespace prefix Function Name

The function name must follow the standard Java method naming standards where the name should be Lower-Camel-Case.

Example: getCurrentDate, getEBMHeaderValue, ... Function Implementation Class

You can have one or more function implemented in the same class. The class name must follow the Java class naming standard where it should be Upper-Camel-Case and convey the functionality of the functions it implements.

Example: EBMHeaderUtils, RoutingUtils, ... Function Implementation Method

The implementation class will have a method for each XPath function. The method should be named the same as the function name. The parameter's data types should match the function parameter data types. If there are optional parameters in the function, you should have a different overloaded method to handle the extra optional parameters.

Example: getCurrentDate, getEBMHeaderValue, ... Function Inner Class

There should be an inner-class for each XPath function named exactly as the Upper-Camel-Case of the function with a 'Function' suffix. The inner class is only needed to access the XPath function from BPEL. The inner class will have to implement the interface.

Example: GetESBHeaderValueFunction, ... Function Namespace

For the function to appear in both the BPEL expression builder wizard and the XSL Mapper, the namespace must start with: then followed by the fully qualified name of the Java class, which implements the function.

Example: Function Namespace Prefix

The namespace prefix must be a readable abbreviation based on functionality.

Example: ebh for GetEBMHeaderValueFunction.

11.1.2 Supported Data Types

The XPath 1.0 and XSL 1.0 data types are supported as return or input parameters to the function, as shown in Table 11-1:

Table 11-1 Supported Data Types for XPath Functions

XPath 1.0/XSL 1.0 Java








Int, float, double,...



11.2 Deploying the XPath/XSL Function in JDeveloper

Custom functions should be registered in JDeveloper to be able to show them with BPEL expression builder and in the XSL Mapper. To do that, provide a User Defined Extension Functions config file [ext-soa-xpath-functions-config.xml], as shown in Example 11-2, and register it with JDeveloper through FilePreferencesXSL Map.

Example 11-2 User Defined Extension Functions Config File

<?xml version="1.0" encoding="UTF-8"?>
<soa-xpath-functions xmlns= xmlns:utl=""
<function name="utl:getCurrentDate">
 <return type="string"/>
  <param name="formatMask" type="string"/> 
<function ...>
 . . .

The implementation classes must be zipped/jared and dropped at:. $SOA_HOME/soa/modules/oracle.soa.ext_11.x.x/classes folder. This way, these classes will be placed in the classpath of WebLogic server.

11.3 Deploying the XPath/XSL Function in the Application Server

The Java XPath function should be registered with the application server. This is done by adding an entry in the ext-soa-xpath-functions-config.xml file, which is found at: $SOA_HOME/soa/modules/oracle.soa.ext_11.x.x/classes\META-INF. This file contains the list and descriptions of all XPath functions defined in the system.

Each function entry in this file has this information:

<function name="utl:getCurrentDate">
 <return type="string"/>
  <param name="formatMask" type="string"/> 

The implementation classes must be dropped at: $SOA_HOME/soa/modules/oracle.soa.ext_11.x.x/classes folder. This way, these classes will be placed in the classpath of the SOA container and available to the classloader.