12c OSB - Java Callout

Sometimes Oracle Service Bus is not sufficient to meet our requirements. To do so OSB provides Java Callout activity that is used to call java code from OSB.

Restrictions to use Java Callout activity:
• Java code must be packaged as jar
• The java method that will be called from OSB, must be static.

Implementation: 
Create an Custom application

 Create a simple java class:Application⇾Project⇾Java class

Create jar that will contain the .class file.

 Jar file is created and Copy the jar file in the OSB project

Create a OSB project to use the created Jar file

Create folder structures like, proxyServices, businessServices, resources etc

 Create a XSD

 Create a Proxy WSDL using the created XSD.

 Move the jar file in JAR folder under resources folder

 Create a Proxy service using that created WSDL

 Proxy and pipeline created

 Drag the Java Callout activity in the pipeline and configure the properties

 Select the class from jar

 Give a variable name for storing the response will be received from the java callout.

 Go the expression and select the inputs

Method: Browser the jar and select the method that you want to call and click OK

Arguments: Set the value of arguments

Return: Assign the variable in which you want to get the output of the method

Drag the log activity and print the variable.

Export the OSB project and deploy to the service bus server,

 Testing: from pipeline

 You can see the response in concatenation of the hello and names under invocation trace

You can observe following issue during the development.

Issue details:

<May 30, 2017 7:17:49 AM MDT> <Error> <oracle.osb.stages.transform.transformloggables> <OSB-382516> <Failed to evaluate expression for callout to java method "public static java.lang.String helloproject.HelloWorld.hello(java.lang.String,java.lang.String)". Argument index: 1, exception: Value of type 'org.apache.xmlbeans.impl.values.XmlAnyTypeImpl' cannot be type-cast to 'java.lang.String'>

Solution:

The error is occurring because it can't pass XmlAnyType TO your static java method. You aren't specifying what you pass to the Java method, so I can only assume you aren't casting it properly to the right type. It gets an XmlAnyTypeImpl which needs to be converted to something else (String, int, boolean, etc.). You can probably just tweak what you're passing to the Java callout using some form of the XS Constructors: