I had difficulty getting started with these tools, so I thought I'd blog my minimal setup. This is all derived from the cometd demo who's war you can find inside the Jetty 6 webapp directory, and who's code you can find inside the contrib/cometd directory of the Jetty 6 source download.
First of all you need to be able to run Jetty (and debug it). I recommend the Run Jetty Run plugin for Eclipse.
Next you need to populate your web.xml for your webapp: (it's quite possible that you don't need all these init params)
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
id="WebApp_ID" version="2.5">
<display-name>comet2</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
<context-param>
<param-name>org.mortbay.jetty.servlet.ManagedAttributes</param-name>
<param-value>org.cometd.bayeux,dojox.cometd.bayeux</param-value>
</context-param>
<servlet>
<servlet-name>game</servlet-name>
<servlet-class>
org.mortbay.cometd.continuation.ContinuationCometdServlet</servlet-class>
<init-param>
<param-name>timeout</param-name>
<param-value>120000</param-value>
</init-param>
<init-param>
<param-name>interval</param-name>
<param-value>0</param-value>
</init-param>
<init-param>
<param-name>maxInterval</param-name>
<param-value>10000</param-value>
</init-param>
<init-param>
<param-name>multiFrameInterval</param-name>
<param-value>2000</param-value>
</init-param>
<init-param>
<param-name>logLevel</param-name>
<param-value>0</param-value>
</init-param>
<init-param>
<param-name>directDeliver</param-name>
<param-value>true</param-value>
</init-param>
<init-param>
<param-name>refsThreshold</param-name>
<param-value>10</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>game</servlet-name>
<url-pattern>/game/*</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>gameServlet</servlet-name>
<servlet-class>server.GameServlet</servlet-class>
<load-on-startup>2</load-on-startup>
</servlet>
</web-app>
package server;
import java.io.IOException;
import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;
import org.cometd.Bayeux;
import org.mortbay.cometd.ext.AcknowledgedMessagesExtension;
import org.mortbay.cometd.ext.TimesyncExtension;
public class GameServlet extends GenericServlet {
@Override
public void service(ServletRequest req, ServletResponse res)
throws ServletException, IOException {
((HttpServletResponse)res).sendError(503);
}
@Override
public void init() throws ServletException {
super.init();
Bayeux bayeux=(Bayeux)getServletContext().getAttribute(Bayeux.DOJOX_COMETD_BAYEUX);
new GameService(bayeux);
bayeux.addExtension(new TimesyncExtension());
bayeux.addExtension(new AcknowledgedMessagesExtension());
}
}
send() method to send messages to clients. Mine looks like this:
package server;
import java.util.Map;
import org.cometd.Bayeux;
import org.cometd.Client;
import org.mortbay.cometd.BayeuxService;
public class GameService extends BayeuxService {
private GameState state = new GameState();
public GameService(Bayeux bayeux) {
super(bayeux, "game");
subscribe("/game/join", "join");
subscribe("/game/event", "event");
}
public void join(final Client joiner, final String channelName, Map<String, Object> data, final String messageId) {
send(joiner, "/game/state", state.getData(), null)
}
public void event(final Client joiner, final String channelName, Map<String, Object> data, final String messageId) {
// TODO
}
}
var _connected = false;
function _metaConnect(message)
{
var wasConnected = _connected;
_connected = message.successful;
if (_connected && !wasConnected)
{
$.cometd.startBatch();
$.cometd.subscribe('/game/state', this, receive);
$.cometd.publish('/game/join', {});
$.cometd.endBatch();
}
}
function join()
{
$.cometd.addListener('/meta/connect', this, _metaConnect);
var cometURL = document.location.protocol + '//' + document.location.hostname + ':' + document.location.port + '/c2/game';
$.cometd.init(cometURL);
}
function send(data) {
$.cometd.publish('/game/event', data);
}
function receive(message)
{
// handle message.data content
}
join();
/c2 is the context name of my webapp in Jetty.
One last point, I used the same includes in my index.html as the cometd chat example did:
<script type="text/javascript" src="jquery/json2.js"></script>
<script type="text/javascript" src="jquery/jquery.js"></script>
<script type="text/javascript" src="jquery/jquery.cometd.js"></script>
