Salut,
falcon wrote:
> I think part of the reason I am struggling is that the programming model of
> comet is different from that of core, non-web, java.
>
> Many comet (or bayeux) examples seem to work through channels. If, in
> Javascript, I subscribe to a channel as
> "comet.subscribe("/somechannel",callbackfunction);" somewhere in Java, I
> expect to be able to do the following:
>
> comet.sendMessage("/somechannel","message:"+rnd.next());//java code
> (along with the ability to control who the message is sent to...broadcast to
> everyone on the target web page, or only to a specific web page viewer)
>
This is interesting :-) If you want to use Java instead of JavaScript
(hence cometd), you need to use the Grizzly Comet Framework (not the
cometd/bayeux implementation). With Grizzly Comet, you can do exactly
what you described above. Take a look at:
http://weblogs.java.net/blog/jfarcand/archive/2006/10/writting_a_come.html
Mainly, You can push data using:
CometContext.notify()[1]
You can broadcast to all or to a limited subset using:
CometContext.getNotificationHandler().notify(..)[2]
You can decide which page gets updated:
CometHandler.onEvent(..)[3]
> Correpondingly, in Java, I expect to be able to listen to messages in a
> manner similar to the following:
> comet.addListener("/somechannel",new cometMessageHandler());//java code
CometContext.addCometListener() [4]
>
> DWR works somewhat like this, but I prefer to use grizzly's implementation
> which lets me get at very low level comet if I need to (althouhg right now
> that is proving to be a bit of a problem).
Thanks. Hopefully the above helps. Let us know if you need more info.
A+
-- Jeanfrancois
[1]
https://grizzly.dev.java.net/nonav/apidocs/com/sun/grizzly/comet/CometContext.html#notify(E)
[2]
https://grizzly.dev.java.net/nonav/apidocs/com/sun/grizzly/comet/NotificationHandler.html
[3]
https://grizzly.dev.java.net/nonav/apidocs/com/sun/grizzly/comet/CometHandler.html#onEvent(com.sun.grizzly.comet.CometEvent)
[4]
https://grizzly.dev.java.net/nonav/apidocs/com/sun/grizzly/comet/CometContext.html#addCometHandler(com.sun.grizzly.comet.CometHandler)
>
>
> Jeanfrancois Arcand-2 wrote:
>> Salut,
>>
>> falcon wrote:
>>> Hi,
>>> I need to embed a web/comet server inside another server. Whenever the
>>> main
>>> server is updated, I need to send out these updates to client's browsers
>>> using comet. Since I need to embed the server, I am using some examples
>>> from Jean-Francois's blog in the following manner:
>>>
>>> public static void main(String[] args) throws IOException {
>>> GrizzlyWebServer ws = new GrizzlyWebServer(8080,"./web/");
>>> ws.addGrizzlyAdapter(new GrizzlyAdapter(){
>>>
>>> @Override
>>> public void service(GrizzlyRequest arg0, GrizzlyResponse arg1) {
>>> //for some reason, if I don't add this dummy adapter, I get a 404
>>> error
>>> //with this, I get the index.html correctly...but this is not the
>>> issue
>>>
>>> }});
>>> ws.addAsyncFilter(new CometAsyncFilter());
>>> ws.addGrizzlyAdapter(new CometdAdapter());
>>>
>>> ws.start();
>>> }
>>>
>>> The problem is, I don't really understand where my cometd logic goes.
>> As soon as you add the CometdAdapter, you have installed bayeux support.
>> Hence you are ready to start the Grizzly WS and listen to "bayeux"
>> request.
>>
>>> Do I need to create a servlet (as in this document:
>>> http://docs.sun.com/app/docs/doc/820-4496/ghgxk?a=view)? That would mean
>>> that I have to add a servlet adapter. I have no problem adding a servlet
>>> adapter, but then what is the purpose of CometdAdapter?
>> No, with Bayeux/Cometd, you don't need to add anything. If you want to
>> see an example, take a look at:
>>
>>> https://grizzly.dev.java.net/nonav/xref/com/sun/grizzly/standalone/cometd/Cometd.html#139
>> It not exactly what you are looking at, but it gives you an idea of how
>> internally, when using:
>>
>> java -jar grizzly-cometd-webserver.jar -p 8080
>>
>>
>>> I actually expected that I would pass in some sort of handler to the
>>> CometdAdapter.
>>>
>>> Can someone please help me out of this confusion?
>> Does the above help? Let me know if not and I will try to write a code
>> snippet that can help you. What do you want to do with Cometd? Are you
>> planning to do update using Java or using Javascript?
>>
>> Thanks
>>
>> -- Jeanfrancois
>>
>>
>>> Thanks
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>>
>>
>