websockets- A sensible and clean way to write WebSocket-capable servers in Haskell.

Safe HaskellNone



This module exposes connection internals and should only be used if you really know what you are doing.



data PendingConnection Source #

A new client connected to the server. We haven't accepted the connection yet, though.




acceptRequest :: PendingConnection -> IO Connection Source #

Accept a pending connection, turning it into a Connection.

data AcceptRequest Source #

This datatype allows you to set options for acceptRequestWith. It is strongly recommended to use defaultAcceptRequest and then modify the various fields, that way new fields introduced in the library do not break your code.




acceptRequestWith :: PendingConnection -> AcceptRequest -> IO Connection Source #

This function is like acceptRequest but allows you to set custom options using the AcceptRequest datatype.

rejectRequest Source #


:: PendingConnection

Connection to reject

-> ByteString

Rejection response body

-> IO () 

data RejectRequest Source #

Parameters that allow you to tweak how a request is rejected. Please use defaultRejectRequest and modify fields using record syntax so your code will not break when new fields are added.




rejectRequestWith Source #


:: PendingConnection

Connection to reject

-> RejectRequest

Params on how to reject the request

-> IO () 

data Connection Source #




data ConnectionOptions Source #

Set options for a Connection. Please do not use this constructor directly, but rather use defaultConnectionOptions and then set the fields you want, e.g.:

myOptions = defaultConnectionOptions {connectionStrictUnicode = True}

This way your code does not break if the library introduces new fields.




  • connectionOnPong :: !(IO ())

    Whenever a pong is received, this IO action is executed. It can be used to tickle connections or fire missiles.

  • connectionCompressionOptions :: !CompressionOptions
  • connectionStrictUnicode :: !Bool

    Enable strict unicode on the connection. This means that if a client (or server) sends invalid UTF-8, we will throw a UnicodeException rather than replacing it by the unicode replacement character U+FFFD.

  • connectionFramePayloadSizeLimit :: !SizeLimit

    The maximum size for incoming frame payload size in bytes. If a frame exceeds this limit, a ParseException is thrown.

  • connectionMessageDataSizeLimit :: !SizeLimit

    connectionFrameSizeLimit is often not enough since a malicious client can send many small frames to create a huge message. This limit allows you to protect from that. If a message exceeds this limit, a ParseException is thrown.

    Note that, if compression is enabled, we check the size of the compressed messages, as well as the size of the uncompressed messages as we are deflating them to ensure we don't use too much memory in any case.

defaultConnectionOptions :: ConnectionOptions Source #

The default connection options:

  • Nothing happens when a pong is received.
  • Compression is disabled.
  • Lenient unicode decoding.

receiveDataMessage :: Connection -> IO DataMessage Source #

Receive an application message. Automatically respond to control messages.

When the peer sends a close control message, an exception of type CloseRequest is thrown. The peer can send a close control message either to initiate a close or in response to a close message we have sent to the peer. In either case the CloseRequest exception will be thrown. The RFC specifies that the server is responsible for closing the TCP connection, which should happen after receiving the CloseRequest exception from this function.

This will throw ConnectionClosed if the TCP connection dies unexpectedly.

receiveData :: WebSocketsData a => Connection -> IO a Source #

Receive a message, converting it to whatever format is needed.

sendDataMessage :: Connection -> DataMessage -> IO () Source #

Send a Message. This allows you send both human-readable text and binary data. This is a slightly more low-level interface than sendTextData or sendBinaryData.

sendDataMessages :: Connection -> [DataMessage] -> IO () Source #

Send a collection of Messages. This is more efficient than calling sendDataMessage many times.

sendTextData :: WebSocketsData a => Connection -> a -> IO () Source #

Send a textual message. The message will be encoded as UTF-8. This should be the default choice for human-readable text-based protocols such as JSON.

sendTextDatas :: WebSocketsData a => Connection -> [a] -> IO () Source #

Send a number of textual messages. This is more efficient than calling sendTextData many times.

sendBinaryData :: WebSocketsData a => Connection -> a -> IO () Source #

Send a binary message. This is useful for sending binary blobs, e.g. images, data encoded with MessagePack, images...

sendBinaryDatas :: WebSocketsData a => Connection -> [a] -> IO () Source #

Send a number of binary messages. This is more efficient than calling sendBinaryData many times.

sendClose :: WebSocketsData a => Connection -> a -> IO () Source #

Send a friendly close message. Note that after sending this message, you should still continue calling receiveDataMessage to process any in-flight messages. The peer will eventually respond with a close control message of its own which will cause receiveDataMessage to throw the CloseRequest exception. This exception is when you can finally consider the connection closed.

sendCloseCode :: WebSocketsData a => Connection -> Word16 -> a -> IO () Source #

Send a friendly close message and close code. Similar to sendClose, you should continue calling receiveDataMessage until you receive a CloseRequest exception.

See http://tools.ietf.org/html/rfc6455#section-7.4 for a list of close codes.

sendPing :: WebSocketsData a => Connection -> a -> IO () Source #

Send a ping

forkPingThread :: Connection -> Int -> IO () Source #

Forks a ping thread, sending a ping message every n seconds over the connection. The thread dies silently if the connection crashes or is closed.

This is useful to keep idle connections open through proxies and whatnot. Many (but not all) proxies have a 60 second default timeout, so based on that sending a ping every 30 seconds is a good idea.

data PermessageDeflate Source #

Four extension parameters are defined for "permessage-deflate" to help endpoints manage per-connection resource usage.

  • "server_no_context_takeover"
  • "client_no_context_takeover"
  • "server_max_window_bits"
  • "client_max_window_bits"

data SizeLimit Source #

A size limit, in bytes. The Monoid instance takes the minimum limit.


SizeLimit !Int64