diff --git a/Network/Mom/Stompl/Client/Conduit.hs b/Network/Mom/Stompl/Client/Conduit.hs new file mode 100644 --- /dev/null +++ b/Network/Mom/Stompl/Client/Conduit.hs @@ -0,0 +1,118 @@ +------------------------------------------------------------------------------- +-- | +-- Module : Network/Mom/Stompl/Client/Conduit.hs +-- Copyright : (c) Tobias Schoofs +-- License : LGPL +-- Stability : experimental +-- Portability: portable +-- +-- This module provides Conduit interfaces +-- for the stomp-queue library. +-- The interfaces create or receive +-- streams of messages instead of single messages. +-- This approach aims to simplify the integration +-- of messaging into applications by means of well-defined +-- streaming interfaces. +------------------------------------------------------------------------------- +module Network.Mom.Stompl.Client.Conduit ( + -- * Plain message streams + qSource, qSink, + -- * Multipart messages as streams + qMultiSource, qMultiSink) +where + + import qualified Data.Conduit as C + import Codec.MIME.Type (Type) + import Control.Monad.Trans (liftIO) + import System.Timeout + + import Network.Mom.Stompl.Client.Queue + import Network.Mom.Stompl.Frame + + ------------------------------------------------------------------------ + -- | Reads from a 'Reader' queue with timeout + -- and returns a 'C.Producer' of type 'Message' i. + -- + -- The function ends iff the timeout expires + -- and loops infinitely otherwise. + -- + -- Parameters: + -- + -- * 'Reader' i: The input interface, a Stomp 'Reader'. + -- + -- * Int: Timeout in microseconds + ------------------------------------------------------------------------ + qSource :: C.MonadResource m => + Reader i -> Int -> C.Producer m (Message i) + qSource r tmo = go + where go = liftIO (timeout tmo $ readQ r) >>= mbYield + mbYield mbX = case mbX of + Nothing -> return () + Just x -> C.yield x >> go + + ------------------------------------------------------------------------ + -- | Writes a stream of messages to a 'Writer' queue + -- and returns a 'C.Consumer' of type o. + -- The function terminates, when the stream ends. + -- + -- Parameters: + -- + -- * 'Writer' o: The output interface, a Stomp 'Writer'. + -- + -- * 'Type': The mime type of the message content. + -- + -- * ['Header']: Headers to add to each message. + ------------------------------------------------------------------------ + qSink :: C.MonadResource m => + Writer o -> Type -> [Header] -> C.Consumer o m () + qSink w t hs = C.awaitForever $ \x -> liftIO (writeQ w t hs x) + + -- header to mark the last segment of a multipart message ------------- + lastMHdr :: Header + lastMHdr = ("__last__", "true") + + ------------------------------------------------------------------------ + -- | Reads from a 'Reader' queue with timeout + -- and returns a 'C.Producer' of type 'Message' i. + -- The function ends when the timeout expires + -- or after having received a segment that is marked as the last one. + -- Note that multipart messages are not foreseen by the standard. + -- 'qMultiSink' and 'qMultiSource' use a header named \"__last__\" + -- to label the last segment of a multipart message. + -- + -- For parameters, please refer to 'qSource'. + ------------------------------------------------------------------------ + qMultiSource :: C.MonadResource m => + Reader i -> Int -> C.Producer m (Message i) + qMultiSource r tmo = loop + where loop = do + mbX <- liftIO (timeout tmo $ readQ r) + case mbX of + Nothing -> return () + Just x -> case lookup (fst lastMHdr) $ msgHdrs x of + Just "true" -> C.yield x + _ -> C.yield x >> loop + + + ------------------------------------------------------------------------ + -- | Writes a multipart message to a 'Writer' queue + -- and returns a 'C.Consumer' of type o. + -- The function terminates, when the stream ends. + -- The last segment is sent with the header (\"__last__\", \"true\"). + -- Note that multipart messages are not foreseen by the standard. + -- + -- For parameters, please refer to 'qSink'. + ------------------------------------------------------------------------ + qMultiSink :: C.MonadResource m => + Writer o -> Type -> [Header] -> C.Consumer o m () + qMultiSink w t hs = do + mbX <- C.await + case mbX of + Nothing -> return () + Just x -> go x + where hs' = lastMHdr:hs + go x = do + mbY <- C.await + case mbY of + Nothing -> liftIO (writeQ w t hs' x) + Just y -> liftIO (writeQ w t hs x) >> go y diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/license/lgpl-3.0.txt b/license/lgpl-3.0.txt new file mode 100644 --- /dev/null +++ b/license/lgpl-3.0.txt @@ -0,0 +1,165 @@ + GNU LESSER GENERAL PUBLIC LICENSE + Version 3, 29 June 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + + This version 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