{-# LANGUAGE OverloadedStrings #-} {-| A WAI adapter to the HTML5 Server-Sent Events API. -} module Network.Wai.EventSource ( ServerEvent(..), eventSourceAppChan, eventSourceAppIO ) where import Blaze.ByteString.Builder (Builder) import Data.Function (fix) import Control.Concurrent.Chan (Chan, dupChan, readChan) import Control.Monad.IO.Class (liftIO) import Network.HTTP.Types (status200) import Network.Wai (Application, Response, responseStream) import Network.Wai.EventSource.EventStream -- | Make a new WAI EventSource application reading events from -- the given channel. eventSourceAppChan :: Chan ServerEvent -> Application eventSourceAppChan chan req sendResponse = do chan' <- liftIO $ dupChan chan eventSourceAppIO (readChan chan') req sendResponse -- | Make a new WAI EventSource application reading events from -- the given IO action. eventSourceAppIO :: IO ServerEvent -> Application eventSourceAppIO src _ sendResponse = sendResponse $ responseStream status200 [("Content-Type", "text/event-stream")] $ \sendChunk flush -> fix $ \loop -> do se <- src case eventToBuilder se of Nothing -> return () Just b -> sendChunk b >> flush >> loop