CometD publish a message back to a client

问题:

I am having a problem in sending back a message to a client. Below is my code

JavaScript

dojox.cometd.publish('/service/getservice', {                         userid : _USERID,                      }); dojox.cometd.subscribe('/service/getservice', function(             message) {         alert("abc");         alert(message.data.test);     });  Configuration Servlet  bayeux.createIfAbsent("/service/getservice", new ConfigurableServerChannel.Initializer() {          @Override         public void configureChannel(ConfigurableServerChannel channel) {             channel.setPersistent(true);             GetListener channelListner = new GetListener();             channel.addListener(channelListner);         }     }); 

GetListener class

public class GetListener implements MessageListener {  public boolean onMessage(ServerSession ss, ServerChannel sc) {       SomeClassFunction fun = new SomeClassFunction; } } 

SomeClassFunction

class SomeClassFunction(){  } 

here i am creating a boolean variable boolean success; if it is true send a message to client which is in javascript. how to send a message back to client. i have tried this line also.

      remote.deliver(getServerSession(), "/service/getservice",                     message, null); 

but it is giving me an error on remote object and getServerSession method.

回答1:

In order to reach your goal, you don't need to implement listeners nor to configure channels. You may need to add some configuration at a later stage, for example in order to add authorizers.

This is the code for the ConfigurationServlet, taken from this link:

public class ConfigurationServlet extends GenericServlet {     public void init() throws ServletException     {         // Grab the Bayeux object         BayeuxServer bayeux = (BayeuxServer)getServletContext().getAttribute(BayeuxServer.ATTRIBUTE);         new EchoService(bayeux);         // Create other services here          // This is also the place where you can configure the Bayeux object         // by adding extensions or specifying a SecurityPolicy     }      public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException     {         throw new ServletException();     } } 

This is the code for EchoService class, taken fro this link:

public class EchoService extends AbstractService {     public EchoService(BayeuxServer bayeuxServer)     {         super(bayeuxServer, "echo");         addService("/echo", "processEcho");     }      public void processEcho(ServerSession remote, Map<String, Object> data)     {         // if you want to echo the message to the client that sent the message         remote.deliver(getServerSession(), "/echo", data, null);          // if you want to send the message to all the subscribers of the "/myChannel" channel         getBayeux().createIfAbsent("/myChannel");         getBayeux().getChannel("/myChannel").publish(getServerSession(), data, null);     } } 

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