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Re: Asynchronous updates/notifications

From: Klaus H. Wolf <wolf@informatik.uni-ulm.de>
Date: Tue, 22 Jun 1999 17:56:57 +0200
Message-ID: <376FB249.996AE194@informatik.uni-ulm.de>
To: Fisher Mark <fisherm@tce.com>
CC: http-wg@cuckoo.hpl.hp.com
I am working in the Internet Presence and Instant Messages field. As you know,
presence needs asynchonous notifications as well. 

We are using a protocol for 2 years now which does:
1) subscriptions from client to server
2) notifications from server to client w/o open connection
3) if 2) is not possible, it uses a Unix-select-like mechanism thru HTTP 
   with open connection. Notifications travel from server to client while 
   TCP connections are established from client to sever. 

You might have a look into the Internet-Draft: draft-wolf-vpp-01.txt. 
Search for NOTIFY and SELECT. 
Or: go to http://rr-vs.informatik.uni-ulm.de/rr/ and watch the TCP traffic
between Java applet and server. Everything is encapsulated into HTTP
request-response transactions to be HTTP-proxy compatible. We are very happy
with the select-mechanism. Tell me, if you need more information. I can write
an Internet Draft. Planned this anyway since the HTTP-SELECT experience could
be valuable for others as well. 
-- 
Klaus H. Wolf                                   Voice: +49 (731) 502 4145
Distributed Systems Dept.                     Ethernet: 08:00:20:12:2a:01
University of Ulm                          Cobrow: http://www.cobrow.com/
89069 Ulm, Germany     Live: http://www.cobrow.com/pages/people/wolf.html
Received on Tuesday, 22 June 1999 16:58:41 EDT

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