Hi all, I'm thinking about using Twisted to rewrite some communications in a Grid computing application. E.g.: [JobServer]1 ---------- *[Proxy]1 ----------- *[Agents] Agents get jobs, report status, results, etc through Proxy to JobServer. Agents are often distributed across a private network that has no external interface, hence the proxy, which is run on a machine between the private network and internet. Also, the proxy may do some caching/queuing of particular messages - especially where the number of agents behind it is large. What we have at present is a TCP socket server however we're starting to hit scalability issues and on top of that our future plans necessitate a notification framework. I've been digging around on twistedmatrix.com and in the book but so far am having trouble finding any guidance or the level of detail that tells me whether Twisted has what we need, some bits of which are: - we'd like to use a persistent stream/connection, at least between the JobServer and Proxy (traffic frequency will be reasonably high) - it needs to be interoperable with java (is there PB for java?) - each end of the connection should be able to register for and get notifications from the other (e.g. Agent gives a heartbeat, JobServer tells Agent to stop) - sometimes the Proxy might be behind a firewall and only able to connect out, we need to be able to use that connection to go back as above - we want to dynamically configure streaming connections between Proxies Hopefully that's enough context for you to point at modules and tell whether these are appropriate questions: Can I re-use a TCP stream for multiple XML-RPC or PB operations? If so, would it make sense to have the client (e.g. Proxy or Agent) initiate the connection and then make a rpc (e.g. "notify me of anything relevant") to the server which would eventually return when something relevant came along - triggering a callback in the client... wash, rinse, repeat? Sorry if I'm overlooking something that already answers this, it doesn't seem like something too unique to have not been asked before... Regards, -Blair -- In science one tries to tell people, in such a way as to be understood by everyone, something that no one ever knew before. But in poetry, it's the exact opposite. - Paul Dirac