Hcoap is a haskell CoAP library. See http://coap.technology/ for more information about the CoAP protocol. The library aims to support RFC 7252 specification, and currently only support non-secure CoAP transport.

The library is split into a high-level API in Network.CoAP.Server and Network.CoAP.Client, and a lower layer API in Network.CoAP.Message for working directly with CoAP messages.

Example server

main =
  withSocketsDo $ do
    sock <- socket AF_INET6 Datagram defaultProtocol
    bindSocket sock (SockAddrInet6 5683 0 iN6ADDR_ANY 0)
    server <- createServer (createUDPTransport sock) (\(request, _) -> do
      let payload = Just (B.pack "{\"value\":\"foo\"}")
      return (Response Content [ContentFormat ApplicationJson] payload))
    runServer server

Example client

main = do
  let request = Request { requestMethod = GET
                        , requestOptions = []
                        , requestPayload = Nothing
                        , requestReliable = True }
withSocketsDo $ do
  sock <- socket AF_INET6 Datagram defaultProtocol
  bindSocket sock (SockAddrInet6 0 0 iN6ADDR_ANY 0)
  let transport = createUDPTransport sock
  client <- createClient transport
  uri <- parseURI "coap://[::1]:5683/hello"
  response <- doRequest client uri request
  putStrLn ("Got response: " ++ show response)
  return ()