Hi, Suppose you've got two tasks, A and B, A wants sends a request to B, B sends a response. Both are sent through Control.Concurrent.Chan: +---+ +---+ | A |<--aChan bChan-->| B | +---+ +---+ A writes to bChan, B writes to aChan.
Because B gets requests from several tasks, the request (and the type of bChan) includes aChan. As long as these tasks are threads of the same process, that's fine. But what can you do if there's a network (or some other kind of IPC) in between? If you didn't need to respond, you could try something like this: +---+ +---+ +---+ +---+ | A | cChan-->| C |--network--| D | bChan-->| B | +---+ +---+ +---+ +---+ A sends to cChan. C serializes the request, D deserializes it and sends to bChan. If you want to respond, it gets difficult. In order to send aChan through the network, you have to serialize it. When deserializing it, you have to create a channel in the process of D and B, which you can write into bChan and which B uses to respond. This channel will be read by a task which serializes the response, sends it through the network to the process of A and C, where it will be deserialized and written to aChan. Of course, you need to keep the serializing/deserializing in both processes consistent. For example by using the same shared object. Looks quite difficult. Are there any simpler solutions for typesafe network-communications? Are there plans to include some kind of "network transparent channels" in the haskell library (or are they already there and I overlooked them)? Sebastian Setzer _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
