On 10 April 2013 14:56, Michael Snoyman
It doesn't seem like you're trying to perform multiple actions simultaneously. For example, you don't need to be able to read from the server and send data back at the same time. Instead, you'll have a single thread of execution. Am I right?
Not exaclty, user code is not only SeverMessage driven but can generate messages and works on it's own (time-events, or some external events). For example user code may generate random messages even there is no message from server, (i.e. wait for some timeout and then feed sender with message), or do some long running events, (e.g. wait for 5 minutes), in both of those cases one threaded pipeline is broken. If so, it seems like the simplest thing would be for you to allow users to
write something like:
Conduit MsgFromServer m MsgToServer
Assuming you had conduits to convert an incoming byte stream to a stream of MsgFromServer and the equivalent for sending, you'd end up with something like:
appSource appData $$ toMsgFromServer =$ clientSuppliedConduit =$ fromMsgToServer =$ appSink appData
Michael
On Tue, Apr 9, 2013 at 1:09 PM, Alexander V Vershilov < alexander.vershilov@gmail.com> wrote:
Hello.
I have next problem: I have a network client that connects to server, listens for messages and generate responces. So the control flow can be represended as:
server -- input -> {generate output} -> output
Output can be generated using default implementation or can overriden by user.
The main difficulty appeares when I need to add a user program on the top of this logic, i.e. from user-side I want to have dsl:smth like
withClient $ do x <- send message waitFor x timeout 5000000 forever $ sendRandomMessage
i.e. an ability to send messages, waiting for some event (message to come), waiting for timeout.
The question is how to define such logic without a big overhead. I see a solution using conduit, it's possible to create 3 processes: listener, user, sender.
+----> user ----+ | | -input -> listener +----------------->+---- sender ->
and use TQueue or TChan to send messages between them, however there can be another possible solutions, that uses less resources, or another design.
-- Alexander
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-- Alexander