Oracle Service Bus 11g, Using Custom Xpath functions

In the new Oracle Service Bus 11g, Oracle gives us new functionality for the use of custom xpath functions.
These functions we eventually can re-use in for example the xslt or xquery transformations.

For this we need :

1. 1. XML Configuration file (osb-custom.xml)
2. 2. Property file (optional, osb-custom.properties)
3. 3. Custom Function Class (jar package)

All these files need to be stored at the next location

<OSB_HOME>/config/xpath-functions

1. XML Configuration file

Create a new XML configuration file. I made a copy of the default file, osb-built-in.xml, edit that one, and change the settings.

<?xml version="1.0" encoding="UTF-8"?>
<xpf:xpathFunctions xmlns:xpf="http://www.bea.com/wli/sb/xpath/config">
    <xpf:category id="%OSB_FUNCTIONS%">
        <xpf:function>
            <xpf:name>customConcat</xpf:name>
            <xpf:comment>%FUNC_CUSTOM_CONCAT_COMMENT%</xpf:comment>
            <xpf:namespaceURI>http://nl.iteye/osb/custom/functions/OsbUtils</xpf:namespaceURI>
            <xpf:className>nl.iteye.osb.custom.functions.OsbUtils</xpf:className>
            <xpf:method>java.lang.String customConcat(java.lang.String, java.lang.String)</xpf:method>
            <xpf:isDeterministic>false</xpf:isDeterministic>
            <xpf:scope>Pipeline</xpf:scope>
            <xpf:scope>SplitJoin</xpf:scope>
        </xpf:function>
    </xpf:category>
</xpf:xpathFunctions>

A few notes on this file.

• category, the name of the category how it will appear in the IDE or Console
• function:name,comments, the description of the function how it will appear in the IDE or Console
• namespaceURI, the namespace which will be imported in for example the xquery to identify the custom function
• className, the java implementation of our custom xpath function
• method, the name of the method which we will be using for the implentation of the function
• isDeterministic, A value of true or false declaring whether or not the function is deterministic, the XQuery standard recommends the function to be deterministic (see documentation for further information)
• scope, i assume the scope of the OSB flow in which the function can be used

2. Property file

%OSB_FUNCTIONS%=Service Bus Functions
%FUNC_CUSTOM_CONCAT_COMMENT%=Returns the concat of the first and the second parameter

Not much in here,just a few placeholders for the descriptions

3. Custom Function Class

Create a new Java project in your favorite IDE. Create a new package and java class. For this demo i created a custom concat function which will concat parameter1 and parameter2 and return the result.

package nl.iteye.osb.custom.functions;       

public class OsbUtils {
    public OsbUtils() {
    }
    
    public static String customConcat(String firstParam, String secondParam) {
        return firstParam + " " + secondParam;
     }
}

The method needs to be defined as static.
Compile the code and create a jar archive and store this at the location mentioned in the top of the article.
After this we should have 3 extra files in this directory :

• osb-custom.xml
• osb-custom.properties
• osb-custom.jar

Restart the server, so the Oracle Service Bus will load the custom classes we just created. Check the output of the console to see if don’t see any errors come by. Wrong configuration (wrong methodname,package, etc) will end up with a little stacktrace in here.

Testing

To test the custom xpath function, create a new Oracle Service Bus project in Eclipse.

Add new XML Schema

<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.example.org/NewXMLSchema" xmlns:tns="http://www.example.org/NewXMLSchema" elementFormDefault="qualified">
    <element name="Input" type="tns:InputType"></element>
    <element name="Output" type="string"></element>

    <complexType name="InputType">
    	<sequence>
    		<element name="Name1" type="string"></element>
    		<element name="Name2" type="string"></element>
    	</sequence>
    </complexType>
</schema>

Add new XQuery Transformation
In the list of expression functions we will see our custom function (customConcat)

(:: pragma bea:global-element-parameter parameter="$input1" element="ns0:Input" location="NewXMLSchema.xsd" ::)
(:: pragma bea:global-element-return element="ns0:Output" location="NewXMLSchema.xsd" ::)

declare namespace ns0 = "http://www.example.org/NewXMLSchema";
declare namespace xf = "http://tempuri.org/OSB%20Project%201/InputToOutput/";

declare function xf:InputToOutput($input1 as element(ns0:Input))
    as element(ns0:Output) {
        <ns0:Output>{ osbK3:customConcat($input1/ns0:Name1,$input1/ns0:Name2) }</ns0:Output>
};

declare variable $input1 as element(ns0:Input) external;

xf:InputToOutput($input1)

In the transformation i will map both the Name1 and Name2 to the input of the custom function, which will return the concat of both in output.

The easiest way to test the result is by running the XQuery on a connected server. Right mouseclick on the .xq file > Run As > Run on Server
The Oracle Service Bus Test Console will pop up.
Fill in the input data and execute.

And the result

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