You can create user-defined (custom) XPath extension functions for use in Oracle SOA Suite. These functions can be created for the following components:

• Oracle BPEL Process Manager

• Oracle Mediator

• XSLT Mapper

• Human workflow

• Shared by all of these components

XPath extension functions in Oracle SOA Suite adhere to the following standards:

• A single schema defines the configuration syntax for both system functions and user-defined functions.

• XPath functions are categorized based on usage (Oracle BPEL Process Manager, Oracle Mediator, human workflow, XSLT Mapper, and those commonly used by all).

• System functions are separated from user-defined functions.

• A repository hosts both system function configuration files and user-defined function configuration files.

• A repository hosts user-defined function implementation JAR files and automatically makes them available for the Java Virtual Machine (JVM) (class loaders).

As a best practice, follow these conventions for creating functions:

• If possible, write functions that can be shared across all components. Functions shared by all components can be created in a configuration file named ext-soa-xpath-functions-config.xml. You must implement XSLT Mapper functions differently than Oracle BPEL Process Manager, Oracle Mediator, and human workflow functions.

  For more information about these implementation differences, see How to Implement User-Defined XPath Extension Functions.

• If you create a function for one component that cannot be used by others (for example, a function for Oracle BPEL Process Manager that cannot be used by Oracle Mediator or human workflow), then create that function in the configuration file specific to that component. For this example, the Oracle BPEL Process Manager function must be created in a configuration file named ext-bpel-xpath-functions-config.xml.

The types and their equivalent Java types can be used for parameter and return values:

The following example shows the function schema used by system and user-defined functions:

<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
 xmlns:tns="http://xmlns.oracle.com/soa/config/xpath" 
 targetNamespace="http://xmlns.oracle.com/soa/config/xpath"
 elementFormDefault="qualified">
      <element name="soa-xpath-functions" type="tns:XpathFunctionsConfig"/>
      <element name="function" type="tns:XpathFunction"/>
      <complexType name="XpathFunctionsConfig">
            <sequence>
               <element ref="tns:function" minOccurs="1" maxOccurs="unbounded"/>
            </sequence>
            <attribute name="resourceBundle" type="string"/>
            <attribute name="version" type="string"/>
      </complexType>

      <complexType name="XpathFunction">
            <sequence>
                 <element name="className" type="string"/>
                 <element name="return">
                         <complexType>
                                 <attribute name="type" type="tns:XpathType"
                                     use="required"/>
                         </complexType>
                 </element>
                 <element name="params" type="tns:Params" minOccurs="0"
                         maxOccurs="1"/>
                 <element name="desc">
                         <complexType>
                                 <simpleContent>
                                         <extension base="string">
                                                 <attribute name="resourceKey"
                                                     type="string"/>
                                         </extension>
                                 </simpleContent>
                         </complexType>
                 </element>
                 <element name="detail" minOccurs="0">
                         <complexType>
                                 <simpleContent>
                                         <extension base="string">
                                                 <attribute name="resourceKey"
                                                      type="string"/>
                                         </extension>
                                 </simpleContent>
                         </complexType>
                 </element>
                 <element name="icon" minOccurs="0">
            <complexType>
                     <simpleContent>
                              <extension base="string">
                                    <attribute name="resourceKey"
                                       type="string"/>
                              </extension>
                     </simpleContent>
             </complexType>
        </element>
                      <element name="helpURL" minOccurs="0">
             <complexType>
                      <simpleContent>
                              <extension base="string">
                                    <attribute name="resourceKey"  
                                       type="string"/>
                              </extension>
                      </simpleContent>
              </complexType>
        </element>
        <element name="group" minOccurs="0">
              <complexType>
                      <simpleContent>
                              <extension base="string">
                                   <attribute name="resourceKey" type="string"/>
                              </extension>
                      </simpleContent>
              </complexType>
        </element>
        <element name="wizardClass" type="string" minOccurs="0"/> 
</sequence>
<attribute name="name" type="string" use="required"/>
               <attribute name="deprecated" type="boolean" use="optional"/>
</complexType>

      <complexType name="Params">
      <sequence>
              <element name="param" minOccurs="1" maxOccurs="unbounded">
                      <complexType>
                           <attribute name="name" type="string" use="required"/>
                           <attribute name="type" type="tns:XpathType"
                                 use="required"/>
                           <attribute name="minOccurs" type="string"
                                 default="1"/>
                           <attribute name="maxOccurs" type="string"
                                 default="1"/>
                           <attribute name="wizardEnabled" type="boolean"
                                 default="false"/>
                      </complexType>
              </element>
       </sequence>
  </complexType>
  <simpleType name="XpathType">
       <restriction base="string">
               <enumeration value="string"/>
               <enumeration value="boolean"/>
               <enumeration value="number"/>
               <enumeration value="node-set"/>
               <enumeration value="tree"/>
       </restriction>
  </simpleType>
</schema>