Implement JAX-RPC handlers to access SDO messages

JAX-RPC handlers are invoked during the processing of request and response messages. For messages that are exchanged using the SOAP protocol, each JAX-RPC handler is passed a SOAP-specific MessageContext object. For other protocols, the IBM web services runtime environment passes a MessageContext object that provides a Service Data Objects view of the message. Service Data Objects (SDO) is an open standard for enabling applications to handle data from different data sources in a uniform way, as data graphs.

If the JAX-RPC handler only deals with message context properties, it does not have to be aware of the particular subclass of MessageContext that it is given, because the context property methods are defined by the MessageContext interface itself. If the handler needs to process information contained within the message, it must be coded to work with the required subclasses. Your JAX-RPC handlers should test whether the MessageContext is an instance of the required subclass.

A JAX-RPC handler is given an SDO-specific MessageContext object (an instance of the com.ibm.websphere.webservices.handler.sdo.SDOMessageContext class) rather than the SOAP-specific MessageContext object in the following cases:

• A JAX-RPC client or outbound invocation from the service integration bus invokes a service using the EJB binding.
• A JAX-RPC client is developed against a non-bound WSDL and is retargeted to a destination in the service integration bus.

The SDOMessageContext class provides methods to get and set the com.ibm.websphere.sdo.SDOMessage instance that represents the message being used processed. The SDOMessage has a method to access the SDO DataGraph object that holds the message content as SDO DataObjects.

A JAX-RPC handler can modify the SDO DataGraph contents, but it cannot change the format or schema of the message.

The following example shows code used to access the SDO DataGraph from the MessageContext object in a JAX-RPC handler handleRequest method:

public boolean handleRequest(MessageContext messageContext) {

		// Convert the MessageContext into an SDOMessageContext
		if( messageContext instanceof SDOMessageContext) {
			SDOMessageContext smc = (SDOMessageContext)messageContext;

			// Retrieve the message
			SDOMessage message = smc.getSDOMessage();
		
			// Get the root object in the SDO DataGraph
			DataGraph graph = message.getDataGraph();
			DataObject content = graph.getRootObject();
		
			// Now do something with the message content.....
		}
		return true;
	}