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From: ilya goberman <goberman@msn.com>
To: <users@tomcat.apache.org>
Subject: need guidance on threading model/ functionality of CometProcessor
Date: Wed, 5 Jan 2011 09:53:43 -0600
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Hi=2C
I am trying to use NIO HTTP Tomcat connector org.apache.coyote.Http11NioPro=
tocol to implement Comet streaming to browsers and mobile devices (using To=
mcat org.apache.catalina.comet.CometProcessor).=20
The application opens a persistent Comet connection to receive data from th=
e server.=20
Server then sends data to the client periodically.

My server application has several threads to send data to the clients. One =
thread is assigned a set of clients.
It will be possible that one of the clients is "slow reader" for various re=
asons.=20

If I call PrintWriter.print("message") to send data to such client=2C the t=
hread apparently may block causing all clients assigned to the thread to st=
op receiving updates.
Clearly=2C this is not going to fly and I need to make some changes to addr=
ess it.

I am looking for 2 things:
1) I need to understand threading for Http11NioProtocol/CometProcessor. Are=
 there any articles/ docs describing how it works?
Could someone point me to it?
It will help any developer using this in the future if it is properly docum=
ented.=20
Apparently there are buffers associated with clients. There is a buffer of =
32K(?) associated with the client that causes writes to block when full (?)=
.
Mark Thomas gave me some pointers=2C but I am still far from understanding =
the whole picture.

2) I need to detect if client is "slow reader". I do not see any way to do =
it besides accessing the client queue and checking its size.
Will it be possible to expose it in the Comet API? I should be able to conf=
igure its size and disconnect clients with queue reaching a threshold.
I suppose I can spawn a thread for each client=2C but this is ugly.

Any suggestions will be appreciated.
Thanks=20

 		 	   		  =

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