HandlerChain

   

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Handler

javax.xml.rpc.handler

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JAX-RPC 1.0; JWSDP 1.0, J2EE 1.4

 public interface Handler {  // Public Instance Methods  public abstract void destroy(  );      public abstract javax.xml.namespace.QName[ ] getHeaders(  );      public abstract boolean handleFault(MessageContext   context   );      public abstract boolean handleRequest(MessageContext   context   );     public abstract boolean handleResponse(MessageContext   context   );     public abstract void init( HandlerInfo   config   );  } 

The Handler interface defines the methods that must be implemented by a message handler. The init( ) and destroy( ) methods mark the beginning and end of the handler's life cycle. The init( ) method receives a Map containing property values that are typically set from a configuration file such as the jaxrpc -ri.xml file used by wsdeploy , the config.xml used by wscompile , or the webservices .xml file supplied to the J2EE 1.4 j2eec utility. The getHeaders( ) method returns the URIs of all of the headers that the handler can process, in the form of an array of javax.xml.namespace.QName objects. A handler whose processing is not directly related to a header should return an empty array.

The handler processing is carried out by the handleRequest( ) , handleResponse( ) , and handleFault( ) methods, which are called for an outgoing message, an incoming message that is not a fault, and a fault, respectively. Each of these methods is passed a MessageContext object that handlers can use to store state that can then be read by other handlers in the chain. The MessageContext object can also be used to retrieve the message itself. If a handler successfully processes a message, it should return true from these methods. If an error occurs that should result in message processing being interrupted , the handler should substitute a fault message for the original and return false. A handler may also throw an exception from one of its handleXXX( ) methods to report an exceptional condition. This exception is thrown to the application that sent the message. There are also cases in which a handler might wish to terminate handling of a message without reporting an error. For example, a handler might cache the replies to requests that it has already seen. In this case, the handler should replace the message with its cached response and return false. For examples that illustrate the possible uses of a handler, refer to Chapter 6.

Implementations

GenericHandler

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