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Jetty example source code file (ContinuationCometdServlet.java)

This example Jetty source code file (ContinuationCometdServlet.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Jetty tags/keywords

abstractcometdservlet, clientimpl, continuation, http, httpservletresponse, io, ioexception, ioexception, list, message, message, request, response, servlet, servletexception, servletexception, string, string, transport, util

The Jetty ContinuationCometdServlet.java source code

package org.mortbay.cometd.continuation;
//========================================================================
//Copyright 2007 Mort Bay Consulting Pty. Ltd.
//------------------------------------------------------------------------
//Licensed under the Apache License, Version 2.0 (the "License");
//you may not use this file except in compliance with the License.
//You may obtain a copy of the License at 
//http://www.apache.org/licenses/LICENSE-2.0
//Unless required by applicable law or agreed to in writing, software
//distributed under the License is distributed on an "AS IS" BASIS,
//WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//See the License for the specific language governing permissions and
//limitations under the License.
//========================================================================

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.mortbay.cometd.AbstractBayeux;
import org.mortbay.cometd.AbstractCometdServlet;
import org.mortbay.cometd.ClientImpl;
import org.mortbay.cometd.MessageImpl;
import org.mortbay.cometd.Transport;
import org.mortbay.util.ajax.Continuation;
import org.mortbay.util.ajax.ContinuationSupport;

import dojox.cometd.Extension;
import dojox.cometd.Message;

public class ContinuationCometdServlet extends AbstractCometdServlet
{
    /* ------------------------------------------------------------ */
    protected AbstractBayeux newBayeux()
    {
        return new ContinuationBayeux();
    }

    /* ------------------------------------------------------------ */
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        doPost(req,resp);
    }

    /* ------------------------------------------------------------ */
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        // Look for an existing client and protect from context restarts
        Object clientObj=req.getAttribute(CLIENT_ATTR);
        ContinuationClient client=(clientObj instanceof ClientImpl)?(ContinuationClient)clientObj:null;
        Transport transport=null;
        boolean connect=false;
        int num_msgs=-1;
        
        // Have we seen this request before
        if (client!=null)
        {
            // yes - extract saved properties
            transport=(Transport)req.getAttribute(TRANSPORT_ATTR);
            transport.setResponse(resp);
        }
        else
        {
            Message[] messages = getMessages(req);
            num_msgs=messages.length;

            /* check jsonp parameter */
            String jsonpParam=req.getParameter("jsonp");

            // Handle all messages
            try
            {
                for (Message message : messages)
                {
                    if (jsonpParam!=null)
                        message.put("jsonp",jsonpParam);

                    if (client==null)
                    {   
                        client=(ContinuationClient)_bayeux.getClient((String)message.get(AbstractBayeux.CLIENT_FIELD));

                        // If no client,  SHOULD be a handshake, so force a transport and handle
                        if (client==null)
                        {
                            // Setup a browser ID
                            String browser_id=browserId(req);
                            if (browser_id==null)
                                browser_id=newBrowserId(req,resp);

                            if (transport==null)
                            {
                                transport=_bayeux.newTransport(client,message);
                                transport.setResponse(resp);
                            }
                            _bayeux.handle(null,transport,message);
                            message=null;

                            continue;
                        }
                        else
                        {
                            String browser_id=browserId(req);
                            if (browser_id!=null && (client.getBrowserId()==null || !client.getBrowserId().equals(browser_id)))
                                client.setBrowserId(browser_id);

                            // resolve transport
                            if (transport==null)
                            {
                                transport=_bayeux.newTransport(client,message);
                                transport.setResponse(resp);
                            }

                            // Tell client to hold messages as a response is likely to be sent.
                            if (!transport.alwaysResumePoll())
                                client.responsePending();
                        }
                    }

                    String channel=_bayeux.handle(client,transport,message);
                    connect|=AbstractBayeux.META_CONNECT.equals(channel);
                }
            }
            finally
            {
                if (transport!=null && client!=null && !transport.alwaysResumePoll())
                    client.responded();
                
                for (Message message : messages)
                    ((MessageImpl)message).decRef();
            }
        }

        // Do we need to wait for messages
        if (transport!=null)
        {
            Message pollReply=transport.getPollReply();
            if (pollReply!=null)
            {
                if (_bayeux.isLogDebug())
                    _bayeux.logDebug("doPost: transport is polling");
                long timeout=client.getTimeout();
                if (timeout==0)
                    timeout=_bayeux.getTimeout();

                Continuation continuation=ContinuationSupport.getContinuation(req,client);
                if (!continuation.isPending())
                    client.access();

                // Get messages or wait
                synchronized (client)
                {
                    if (!client.hasMessages() && !continuation.isPending()&& num_msgs<=1)
                    {
                        // save state and suspend
                        ((ContinuationClient)client).setContinuation(continuation);
                        req.setAttribute(CLIENT_ATTR,client);
                        req.setAttribute(TRANSPORT_ATTR,transport);
                        continuation.suspend(timeout);
                    }
                    continuation.reset();
                }

                ((ContinuationClient)client).setContinuation(null);
                transport.setPollReply(null);

                for (Extension e:_bayeux.getExtensions())
                    pollReply=e.sendMeta(pollReply);
                transport.send(pollReply);                 
            }
            else if (client!=null)
            {
                client.access();
            }
        }


        // Send any messages.
        if (client!=null) 
        { 
            List<Message> messages = null; 
            Message message = null; 
            synchronized(client)
            {
                switch (client.getMessages())
                {
                    case 0:
                        break;
                    case 1:
                        message = client.takeMessage(); 
                        break;
                    default:
                        messages = client.takeMessages(); 
                        break;
                }
            }
            if (message!=null)
                transport.send(message); 
            else if (messages!=null)
                transport.send(messages); 
            
            if (transport.alwaysResumePoll())
            	client.resume();
        }
        
        if (transport!=null)
            transport.complete();
    }
}

Other Jetty examples (source code examples)

Here is a short list of links related to this Jetty ContinuationCometdServlet.java source code file:

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