This topic applies only to the IBM Business Automation Workflow Advanced
configuration.

Creating an XPath function JAR file

Draft comment:
This topic only applies to BAW, and is located in the BAW repository. Last updated on 2025-03-13 12:15

Define your custom XPath extension functions by creating an XPath function Java™ archive (JAR) file that contains a Java service provider plug-in.

About this task

XPath extension functions are implemented as static Java methods. These Java methods are exposed to the process runtime environment through a Java service provider plug-in. XPath extension functions can be used only in business object lazy parsing mode.

Procedure

In the Java perspective, create a Java project.
Add the bpc_apis.jar external JAR file from the install_root/runtimes/bi_v8_stub/runtimes directory to your build path, where install_root is the directory in which IBM® Integration Designer is installed.
This JAR file contains the com.ibm.bpe.xpath.spi.XPathExtensionFunctionPlugin interface and the com.ibm.bpe.xpath.spi.XPathExtensionFunctionDescriptor class, which are required to create the plug-in.

Write a public static method that implements the XPath function.

Each XPath function is implemented as a static Java method, where the following type mapping applies:

Table 1. XPath to Java type mapping
XPath type	Java type
string	java.lang.String
number	java.lang.Number
boolean	java.lang.Boolean or boolean
object	commonj.sdo.DataObject
node-set	java.util.List

For example, the following Java method implements an XPath function that takes a node-set and a string as parameters and returns a string.

public static String createDelimitedString(List list, String del) {
	StringBuilder sb = new StringBuilder();
	
	if (list.size()< 0) {
		sb.append(list.get(0));
		for (int i=1; i<list.size(); i++) {
			sb.append(del);
			sb.append(list.get(i));
		}
	}

	return sb.toString();
}

To expose your extension functions, implement com.ibm.bpe.xpath.spi.XPathExtensionFunctionPlugin.

Override the getXPathFunctions method, which returns a function descriptor for each function that you provide.

For information about implementing the Java service provider interface, see the Javadoc for the XPathExtensionFunctionPlugin interface in the com.ibm.bpm.xpath.spi package at Reference: Java APIs and SPIs.

The following sample exposes the createDelimitedString method from the previous example, making the method available for all expressions and conditions.

import com.ibm.bpe.xpath.spi.XPathExtensionFunctionDescriptor;
import com.ibm.bpe.xpath.spi.XPathExtensionFunctionPlugin;
public class MyXPathExtensionFunctionPlugin implements XPathExtensionFunctionPlugin {

	@Override
	public XPathExtensionFunctionDescriptor[] getXPathFunctions() {
	return new XPathExtensionFunctionDescriptor[]{
	new XPathExtensionFunctionDescriptor("createDelimitedString", 
	"http://org.custom.xpath",
	"abc", 
	"org.custom.xpath.XPathExtensionFunctions", 
	new XPathExtensionFunctionDescriptor.ParameterType[]{XPathExtensionFunctionDescriptor.ParameterType.NODE_SET,
			XPathExtensionFunctionDescriptor.ParameterType.STRING}, 
			XPathExtensionFunctionDescriptor.ParameterType.STRING, 
			XPathExtensionFunctionDescriptor.ALL_EXPRESSION_TYPES)
	};
	}
}

Create a service provider configuration file for the plug-in in the META-INF/services/ directory of your JAR file.
The configuration file provides the mechanism for the runtime environment to identify and load the plug-in. This file conforms to the Java service provider interface specification.
1. Create a file named com.ibm.bpe.xpath.spi.XPathExtensionFunctionPlugin.
2. In the first line of the file that is not a comment line or a blank line, specify the fully qualified name of the plug-in class that you previously created.
  For example, if your plug-in class is called MyXPathExtensionFunctionPlugin and is in the org.custom.xpath package, the first line of the configuration file must be org.custom.xpath.MyXPathExtensionFunctionPlugin.
Export the JAR file.

What to do next

After you create the XPath function JAR file, you must register the plug-in with IBM Integration Designer for use in the process editor. For more information, see BPEL processes: Registering an XPath function JAR file with IBM Integration Designer.