Real-Time Messages sent, and not received.

[siegersallee]

I'm trying to add Real-Time Messaging to an already large SmartGWT application.

I studied the doc and the examples, and ran one of the examples in a development environment.

We're using GWT 2.6.1 and SmartClient Version: v9.1p_2014-06-04/PowerEdition Deployment (built 2014-06-04) and Eclipse Kepler SR2.

First, I added Real-Time Message handling to the client, with a fair amount of error handling and logging, like so:

public class [B]MyApplication [/B]implements EntryPoint
{
  @Override
  public void onModuleLoad()
  {
    RPCManager.setShowPrompt(true);
    RPCManager.setDefaultTimeout(60000);

    // Handle any Real-Time Messages pushed to us from the server.
    Messaging.subscribe("pushMessage", new MessagingCallback() {
      @Override
      public void execute(Object data)
      {
        System.out.println("");
        System.out.println(">>>  R E C E I V E D ! ! !  <<<");
        System.out.println("");
        ClientReceivePushMessage.receiveAndHandle((JavaScriptObject) data);
      }
    } );

    ...
    // Then, it opens the main window and runs the app.
  }
}

public class [B]ClientReceivePushMessage[/B]
{
  public static void receiveAndHandle(final JavaScriptObject messageJsObj)
  {
    // NOTE: this method is static because doing that allows us to have the casting and error handling
    //       here instead of in the calling method, which is the entry point, so it should be kept simple.

    if (messageJsObj != null)
    {
      final Object messageMap = JSOHelper.convertToJava(messageJsObj);
      if (messageMap instanceof Map)
      {
        @SuppressWarnings("unchecked")
        final PushMessage message = new PushMessage((Map<String, String>) messageMap);

        switch (message.getMessageType())
        {
          case ONE_TYPE:
            System.out.println(">>>  YES!!  Message Received of One Type: " + message.getContents());
            break;
          case ANOTHER_TYPE:
            System.out.println(">>>  YES!!  Message received of Another Type: " + message.getContents());
            break;
          default:
            throw new IllegalArgumentException("PushMessage.receive: unknown MessageType = " + message.getMessageType().toString());
        }
      }
      else
      {
        String msg = "Object has type " + messageMap.getClass().getName() + ", not PushMessage.";
        System.out.println(">>>  ERROR: received " + msg);
        throw new IllegalArgumentException(msg);
      }
    }
    else
    {
      String msg = "Real-Time Message Object is null.";
      System.out.println(">>>  ERROR: received " + msg);
      throw new IllegalArgumentException(msg);
    }
  }
}
 
public class [B]PushMessage[/B]
{
  @SuppressWarnings("unused")
  private static final long serialVersionUID = -9184815913070178774L;
  private PushMessageType   messageType;
  private String            contents;        // This will probably need to get more complex later.

 
  public PushMessage(PushMessageType messageType, String contents)
  {
    this.messageType = messageType;
    this.contents = contents;
  }

  // These next 2 methods are needed because JSOHelper.convertToJava() can
  // only reliably convert collections:

  public PushMessage(Map<String, String> map)
  {
    this.messageType = PushMessageType.valueOf(map.get("MessageType"));
    this.contents = map.get("Contents");
  }

  public Map<String, String> toMap()
  {
    Map<String, String> map = new HashMap<String, String>();
    map.put("PushMessageType", this.messageType.toString());
    map.put("Contents", this.contents);
    return map;
  }
////// getters and setters removed here...
}

public enum [B]PushMessageType [/B]{ ONE_TYPE, ANOTHER_TYPE }   // Obviously, these will be replaced.

In the server code, I inserted this into code that is run often, specifically, the doFilter() method of the filter we use for pretty much everything coming from the server:

  ...
  // Throttle this to once per 10 seconds, at most.
    if (System.currentTimeMillis() > whenLastSend + 10000L)
    {
      ServerPushMessage message = new ServerPushMessage(PushMessageType.ONE_TYPE, "!!!  Here  !!!");
      System.out.println(">>>   Sending...   <<<");
      try
      {
        message.[I][B]send[/B][/I]("pushMessage");
      }
      catch(Exception e)
      {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
      whenLastSend = System.currentTimeMillis();
    }
    ...


public class [B]ServerPushMessage[/B]
{
  private PushMessage message;

  public ServerPushMessage(PushMessageType messageType, String contents)
  {
    message = new PushMessage(messageType, contents);
  }

  public void send(String channel) throws Exception
  {
    ISCMessageDispatcher dispatcher = ISCMessageDispatcher.instance();    // Use the no-arg version in the server.
    dispatcher.[I][B]send[/B][/I](new ISCMessage(channel, message.toMap()));
    System.out.println(">>>  Sent message: " + this.message.getContents() + "  <<<");
  }
}

When I run it in Eclipse, the 2 messages generated by the server code ("Sending" and "Sent") appear in the Eclipse Console about every 10 seconds, but I don't get anything at all from the client. Regarding setup, I added the 3 RTM JARs to war/WEB-INF/lib, and added them to the build path in Eclipse. I added the following to smartgwt.properties, and verified that the settings are present in the generated server.properties in the WAR (removing comments):

         messaging.keepaliveInterval: 3000
         messaging.keepaliveReestablishDelay: 1000
         messaging.connectTimeout: 4000
         messaging.connectionTTL: 120000
         messaging.flushBufferSize: 8096
         messaging.dispatcherImplementer: com.isomorphic.messaging.LocalMessageDispatcher

Finally, I un-commented this paragraph in web.xml:

      <servlet>
        <servlet-name>MessagingServlet</servlet-name>
        <servlet-class>com.isomorphic.messaging.MessagingServlet</servlet-class>
      </servlet>

The final clue I have is that the Eclipse Console shows this:

>>>   Sending...   <<<
>>>  Sent message: !!!  Here  !!!  <<<
[WARN] 404 - GET /triad40/sc/messaging?ts=1446145027750&isc_noLog=1&type=connect&connectionID=isc_HiddenFrame_5&subscribedChannels=%7B%0D%20%20%20%20pushMessage%3A%7B%0D%20%20%20%20%20%20%20%20subscriptionCallback%3Anull%0D%20%20%20%20%7D%0D%7D&eventStream=true (127.0.0.1) 1385 bytes
   Request headers
      Host: 127.0.0.1:8888
      User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0
      Accept: text/event-stream
      Accept-Language: en-US,en;q=0.5
      Accept-Encoding: gzip, deflate
      DNT: 1
      Referer: http://127.0.0.1:8888/Triad40.html?gwt.codesvr=127.0.0.1:9997
      Cookie: GLog=%7B%0D%20%20%20%20trackRPC%3Afalse%0D%7D; JSESSIONID=lb0o31x93ne91d06fx8hovuhy; isc_cState=ready
      Connection: keep-alive
      Pragma: no-cache
      Cache-Control: no-cache
   Response headers
      Content-Type: text/html;charset=ISO-8859-1
      Cache-Control: must-revalidate,no-cache,no-store
      Content-Length: 1385
[WARN] 404 - GET /triad40/sc/messaging?ts=1446145031767&isc_noLog=1&type=connect&connectionID=isc_HiddenFrame_6&subscribedChannels=%7B%0D%20%20%20%20pushMessage%3A%7B%0D%20%20%20%20%20%20%20%20subscriptionCallback%3Anull%0D%20%20%20%20%7D%0D%7D&eventStream=true (127.0.0.1) 1385 bytes
   Request headers
      Host: 127.0.0.1:8888
      User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0
      Accept: text/event-stream
      Accept-Language: en-US,en;q=0.5
      Accept-Encoding: gzip, deflate
      DNT: 1
      Referer: http://127.0.0.1:8888/Triad40.html?gwt.codesvr=127.0.0.1:9997
      Cookie: GLog=%7B%0D%20%20%20%20trackRPC%3Afalse%0D%7D; JSESSIONID=lb0o31x93ne91d06fx8hovuhy; isc_cState=ready
      Connection: keep-alive
      Pragma: no-cache
      Cache-Control: no-cache
   Response headers
      Content-Type: text/html;charset=ISO-8859-1
      Cache-Control: must-revalidate,no-cache,no-store
      Content-Length: 1385

The really curious thing to me is that the GET URL contains a snippet which when URL decoded reads:

subscribedChannels={
    pushMessage:{
        subscriptionCallback:null
    }
}

This is especially curious considering that, when the client (on exit) does a Messaging.getSubscribedChannels(), it gets "pushMessage" as a subscribed channel.

I presume there's some piece of setup or configuration that is missing here. I did my best to follow the directions in the Messaging PDF and the various README files.

What did I miss?

[Isomorphic]

The Messaging servlet is not where the client is expecting it, hence the 404 status code.

Adjust either the path where you registered the servlet in web.xml, or the client-side setting for messagingURL, so that they match.

[siegersallee]

Thanks! It turns out I had to change the MessagingServlet servlet-mapping in web.xml, from /sc/messaging/* to /contextName/sc/messaging/*, in case anyone wants to know. At least, that works in Classic Dev Mode.