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|
{-# 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
|
