How to Import User-Defined Functions

You can create and import a user-defined Java function if you have complex functionality that cannot be performed in XSLT or with XPath expressions.

Follow these steps to create and use your own functions. External, user-defined functions can be necessary when logic is too complex to perform within the XSL map.

To import user-defined functions:

Code and build your functions.
The XSLT Map Editor extension functions are coded differently than the Oracle BPEL Process Manager extension functions. Two examples are provided in the SampleExtensionFunctions.java file of the mapper-107-extension-functions sample scenario. You can download this and other samples on the Sample Code site.

Each function must be declared as a static function. Input parameters and the returned value must be declared as one of the following types:
- java.lang.String
- int
- float
- double
- boolean
- oracle.xml.parser.v2.XMLNodeList
- oracle.xml.parser.v2.XMLDocumentFragment
The text for these functions is as follows:
```
// SampleExtensionFunctions.java
package oracle.sample;
/*
This is a sample XSLT Map Editor User Defined Extension Functions implementation
class.
*/
public class SampleExtensionFunctions
{
   public static Double toKilograms(Double lb)
   {
      return new Double(lb.doubleValue()*0.45359237);
   }
   public static String replaceChar(String inputString, String oldChar, String
      newChar )
   {
      return inputString.replace(oldChar.charAt(0), newChar.charAt(0));
   }
}
```

Create an XML extension function configuration file. This file defines the functions and their parameters.

This file must have the name ext-mapper-xpath-functions-config.xml. See Creating User-Defined XPath Extension Functions for more information on the format of this file. The following syntax represents the functions toKilograms and replaceChar as they are coded in Step 1.

<?xml version="1.0" encoding="UTF-8"?>
<soa-xpath-functions version="11.1.1"
 xmlns="http://xmlns.oracle.com/soa/config/xpath" xmlns:sample=
"http://www.oracle.com/XSL/Transform/java/oracle.sample.SampleExtensionFunctions"
 >
      <function name="sample:toKilograms">
             <className>oracle.sample.SampleExtensionFunctions</className>
             <return type="number"/>
             <params>
                    <param name="pounds" type="number"/>
             </params>
             <desc>Converts a value in pounds to kilograms</desc>
      </function>
      <function name="sample:replaceChar">
             <className>oracle.sample.SampleExtensionFunctions</className>
             <return type="string"/>
             <params>
                    <param name="inputString" type="string"/>
                    <param name="oldChar" type="string"/>
                    <param name="newChar" type="string"/>
             </params>
             <desc>Returns a new string resulting from replacing all occurrences
                   of oldChar in this string with newChar</desc>
      </function>
</soa-xpath-functions>

Some additional rules apply to the definitions of XSLT extension functions:

The functions need a namespace prefix and a namespace. In this sample, they are sample and http://www.oracle.com/XSL/Transform/java/oracle.sample.Sam pleExtensionFunctions.
The function namespace must start with http://www.oracle.com/XSL/Transform/java/ for extension functions to work with the Oracle XSLT processor.
The last portion of the namespace, in this sample oracle.sample.SampleExtensionFunctions, must be the fully qualified name of the Java class that implements the extension functions.

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

XML Configuration File Type Name	Java Type
`string`	`java.lang.String`
`boolean`	`boolean`
`number`	`int`, `float`, `double`
`node-set`	`oracle.xml.parser.v2.XMLNodeList`
`tree`	`oracle.xml.parser.v2.XMLDocumentFragment`

Create a JAR file containing both the XML configuration file and the compiled classes. The configuration file must be contained in the META-INF directory for the JAR file. For the example in this section, the directory structure is as follows with the oracle and META-INF directories added to a JAR file:
- oracle
  - sample (contains the class file)
- META-INF
  - ext-mapper-xpath-functions-config.xml
The JAR file must then be registered with Oracle JDeveloper.
Go to Tools > Preferences > SOA.
Click the Add button and navigate to and select your JAR file.
Restart Oracle JDeveloper.

New functions appear in the Components window under the User Defined page in the User Defined Extension Functions group.
To make the functions available in the runtime environment, see How to Deploy User-Defined Functions to Runtime for details.