Retrieving transport headers with JAX-WS

You can enable a Java API for XML-Based Web Services (JAX-WS) web services client to retrieve values from transport headers. For a request that uses HTTP, the transport headers are retrieved from HTTP headers found in the HTTP response message. For a request that uses Java Message Service (JMS), the transport headers are retrieved from the JMS message properties found on the JMS response message.

You need a JAX-WS web services client that we can enable to retrieve transport headers.

Retrieving transport headers is supported only by Web services clients, and is supported for the HTTP and JMS transports. The web services client must call the JAX-WS APIs directly and not through any intermediary layers, such as a gateway function.

When using JAX-WS, the client must set a property on the BindingProvider's RequestContext object to retrieve values from the transport headers. After we set the property, values are read from responses for the subsequent method invocations against that BindingProvider object until the associated property is set to null or the BindingProvider object is discarded.

To retrieve values from the transport headers on inbound responses, modify the client code as follows:

Tasks

1. Create a java.util.Map object that will hold the transport headers retrieved from the response message. To retrieve all the transport headers from a response message, leave this Map empty.
2. (Optional) Add an entry to the Map for each header that we want to retrieve from the incoming response message.

   1. Set the Map entry key to a string that exactly matches the transport header identifier. We can specify the header identifier with a reserved header name, such as Cookie in the case of HTTP, or the header identifier can be user-defined, such as MyTransportHeader. Certain header identifiers are processed in a unique manner, but no other checks are made to confirm the header identifier value. To learn more about the HTTP header identifiers that have unique consideration, read about transport header properties best practices. We can find common header identifier string constants, such as HTTP_HEADER_SET_COOKIE in the com.ibm.websphere.webservices.Constants class. The Map entry value is ignored and does not need to be set. An empty Map, for example, one that is non-null, but does not contain any keys, causes all the transport headers in the response to be retrieved.

3. Set the Map object on the BindingProvider's RequestContext using the com.ibm.websphere.webservices.Constants.RESPONSE_TRANSPORT_PROPERTIES property. When the Map is set, the RESPONSE_TRANSPORT_PROPERTIES property is used in subsequent invocations to retrieve the headers from the responses. If we set the property to null, no headers are retrieved from the response. To learn more about these properties, see the transport header properties documentation.

4. Invoke remote method calls against the BindingProvider instance. The values from the specified transport headers are retrieved from the response message and placed in the Map.

   If the property is not set correctly, we might experience API usage errors that result in a WebServiceException error. The following requirements must be met, or the process fails:

   • The Constants.RESPONSE_TRANSPORT_PROPERTIES property value that is set on the BindingProvider's RequestContext instance must be either null or an instance of java.util.Map.
   • All the Map keys must be of the java.lang.String data type, and the keys must not be null.

   • The Map may be empty, which means that it contains no entries at all. In this case, all the transport headers will be retrieved from the response message.

You have a JAX-WS web service that can receive transport headers from incoming response messages.

Example

Here is a short programming example that illustrates how response transport headers are retrieved by a JAX-WS Web services client application:

public class MyApplicationClass {
    // Inject an instance of the service's port-type.
    @WebServiceRef(EchoService.class)
    private EchoPortType port;

    // This method will invoke  the web service operation and retrieve transport headers on the request.
    public void invokeService() {

        // Set up the Map to retrieive our response headers.
        Map<String, Object> responseHeaders = new HashMap<String, Object>;
        responseHeaders.put("MyHeader1", null);
        responseHeaders.put("MyHeader2", null);
        responseHeaders.put("MyHeader3", null);

        // Set the Map as a property on the RequestContext.
        BindingProvider bp = (BindingProvider) port;
        bp.getRequestContext().put(com.ibm.websphere.webservices.Constants.RESPONSE_TRANSPORT_PROPERTIES, responseHeaders);

        // Invoke the web services operation.
        String result = port.echoString("Hello, world!");

        // Now retrieve our response headers.
        Object header1 = responseHeaders.get("MyHeader1");
        Object header2 = responseHeaders.get("MyHeader2");
        Object header3 = responseHeaders.get("MyHeader3");

    }
}

Sending transport headers with JAX-WS

Implement extensions to JAX-WS web services clients

Transport header properties best practices