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Posted to users@tomcat.apache.org by Sudeep Pradhan <pr...@vmware.com> on 2011/07/25 20:23:28 UTC

Comet: How to send *Chunked* response 

Hi,

I am using CometProcessor to stream event notifications from server to client. The events are generated at random.  I want to send the notification with Transfer Encoding as chunked so that I can use Apache's ChunkedInputStream to parse the output.

I get the PrintWriter from the ServletResponse using the getWriter() and I write the event notification on this writer. I want this to be in chunk format of length-payload. Currently I do the following:

PrintWriter writer = connection.getWriter();
for (int j = 0; j < pendingEvents.length; j++) {
                                String eventString = converter.convert(pendingEvents[j]);
                                eventString.concat("\r\n");
                                final String length = Integer.toHexString(eventString.length());
                                writer.print("\r\n" + length + "\r\n");
                                writer.print(eventString);
                                //logger.info("Writing:" + eventString);
}

But this generates a Bad Chunk size exception on client.

Thanking you in anticipation.

Sudeep

RE: Comet: How to send *Chunked* response

Posted by Sudeep Pradhan <pr...@vmware.com>.
Mark,

I tried just writing to the PrintWriter. I do not see the chunking in the response. Can you spot any obvious mistake here?

			    private HttpServletResponse connection; // Set in constructor

	                PrintWriter writer = connection.getWriter();
	                for (int j = 0; j < pendingEvents.length; j++) {
	                    String eventString = converter.convert(pendingEvents[j]);
	                    eventString = eventString + "\r\n";
	                    writer.print(eventString);
	                    writer.flush();
	                }

Thanks,
Sudeep

-----Original Message-----
From: Mark Thomas [mailto:markt@apache.org] 
Sent: Monday, July 25, 2011 12:37 PM
To: Tomcat Users List
Subject: Re: Comet: How to send *Chunked* response

On 25/07/2011 19:23, Sudeep Pradhan wrote:
> Hi,
> 
> I am using CometProcessor to stream event notifications from server to client. The events are generated at random.  I want to send the notification with Transfer Encoding as chunked so that I can use Apache's ChunkedInputStream to parse the output.
> 
> I get the PrintWriter from the ServletResponse using the getWriter() and I write the event notification on this writer. I want this to be in chunk format of length-payload. Currently I do the following:
> 
> PrintWriter writer = connection.getWriter();
> for (int j = 0; j < pendingEvents.length; j++) {
>                                 String eventString = converter.convert(pendingEvents[j]);
>                                 eventString.concat("\r\n");
>                                 final String length = Integer.toHexString(eventString.length());
>                                 writer.print("\r\n" + length + "\r\n");
>                                 writer.print(eventString);
>                                 //logger.info("Writing:" + eventString);
> }
> 
> But this generates a Bad Chunk size exception on client.

Just write and flush the content. Tomcat will handle the chunking for you.

Mark



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Re: Comet: How to send *Chunked* response

Posted by Mark Thomas <ma...@apache.org>.
On 25/07/2011 19:23, Sudeep Pradhan wrote:
> Hi,
> 
> I am using CometProcessor to stream event notifications from server to client. The events are generated at random.  I want to send the notification with Transfer Encoding as chunked so that I can use Apache's ChunkedInputStream to parse the output.
> 
> I get the PrintWriter from the ServletResponse using the getWriter() and I write the event notification on this writer. I want this to be in chunk format of length-payload. Currently I do the following:
> 
> PrintWriter writer = connection.getWriter();
> for (int j = 0; j < pendingEvents.length; j++) {
>                                 String eventString = converter.convert(pendingEvents[j]);
>                                 eventString.concat("\r\n");
>                                 final String length = Integer.toHexString(eventString.length());
>                                 writer.print("\r\n" + length + "\r\n");
>                                 writer.print(eventString);
>                                 //logger.info("Writing:" + eventString);
> }
> 
> But this generates a Bad Chunk size exception on client.

Just write and flush the content. Tomcat will handle the chunking for you.

Mark



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