wai-eventsource integration (turn a wai Application into ActionT)

[pxqr]

The problem I've encountered is that it's impossible to turn a wai Application into ActionT. Examples when we might need this includes both wai-eventsource and wai-websockets enabled applications, but lets consider the first one for a moment:

get "/:foo/updates" $ do 
  application (eventSourceAppChan myEventStream)

where application function is impossible to implement because ScottyResponse do not allow to return a plain old wai Response. The workaround is to set middleware with interceptor routing, which is pretty awkward.

[xich]

Ah I can implement this. I'm not near a computer right now, but soon. Thanks for reporting!

[pxqr]

I think the most promising way to fix this issue is to make ScottyResponse more general:

data ScottyResponse = SR
  { srStatus  :: Status
  , srHeaders :: ResponseHeaders -- ^ additional headers to append to the srResponse
  , srResponse :: Network.Wai.Response
  }

I guess it is possible to keep existing API the same. Do you have some considerations against this changes or any better ideas?

[crabmusket]

I've been looking at websockets and Scotty and my current solution is to handle websockets outside the Scotty app. It's not elegant but it works.

[bananu7]

What's the status on that? I wrote a simple handler to test how that could be done:

sse :: T.Text -> ActionM ()
sse t = do
     setCorsHeader
     setHeader "Content-Type" "text/event-stream"
     setHeader "Cache-Control" "no-cache"
     setHeader "Connection" "keep-alive"
     raw $ encodeUtf8 t

And it works, but drops the connection nevertheless.

[liamoc]

Any progress on this issue?

[bsima]

What's the status on that? I wrote a simple handler to test how that could be done:

sse :: T.Text -> ActionM ()
sse t = do
     setCorsHeader
     setHeader "Content-Type" "text/event-stream"
     setHeader "Cache-Control" "no-cache"
     setHeader "Connection" "keep-alive"
     raw $ encodeUtf8 t

And it works, but drops the connection nevertheless.

Why does this drop the connection despite having the keep-alive header?

[ocramz]

Well, now (since #233) you can have nested wai Applications under a Scotty route!