Hi everyone,

[This post is slightly OT because (I think) it's more related to what one 
can/cannot do with the http protocol, than how it can be achieved using 
Ruby libraries]


I am looking for a way to use the observer pattern in a client/server 
architecture.  This would need to work differently from the standard sort 
of request mechanism used by (say) XMLRPC or soap4r.

For example, when invoking a simple service:
(client) establish connection with server
(client) request service
(server) perform service
(server) return results to client and close connection?

However, with the observer pattern - I think I would need:
(client) establish connection
(client) request service
(server) register client connection for later updates
(server) return "ok" result to client - (but don't close connection)
...some time later (connection is still open)...
(server) send notification to client
...some time later (connection is still open)...
(client) request to unregister
(server) close connection

My question is:
Can this sort of thing be done by using any of the ruby comm libraries 
(SOAP, XMLRPC, http-access-2) available from RAA?  
My (limited) understanding of these packages is that they are based 
around the http protocol which closes the connection as soon as the 
server has replied to the client.  
I have downloaded each package and cannot see any obvious ways to do what 
I want - but then again, I don't really know what I am doing :-).  

Apologies for the vagueness of the email, I hope it gets across what I am 
trying to achieve - but given my limited understanding of how the http 
stuff works, it's hard to express more clearly.

Feel free to point me to a FM (as in RTFM) if this is a lame question :-)

Thanks for any pointers you can give.

Cheers,
Martin

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Martin Hart              Tel:    +44 (0) 1582 618468
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