Hello, I've been trying to use the WebSockets library to connect to the coinbase feed. The library seems to be doing something behind the scenes that I'm not expecting. Here is my code:
{-# LANGUAGE ViewPatterns #-} {-# LANGUAGE OverloadedStrings #-}
import Data.Text import Data.Text.Encoding (decodeUtf8) import Network.WebSockets import qualified Data.ByteString.Lazy as LBS
main :: IO () main = runClient "ws-feed.exchange.coinbase.com" 8080 "/" handleConnection handleConnection connection = do send connection initSub let loop = do priceMsg <- receiveDataMessage connection print priceMsg loop
initSub :: Message initSub = DataMessage $ Text "{\"type\":\"subscribe\", \"product_id\":\"BTC-USD\"}"
When I run this, I get a print out showing a malformed response exception with a Moved permanently message. Now, it also shows the location that I was trying to connect to, which is: "https://ws-feed.exchange.coinbase.com/ ". This isn't right, because the websocket feed uses the wss:// protocol rather than https://. i've tried changing the url to be "wss:// ws-feed.exchange.coinbase.com/", but when I try that, dns resolution fails. If I had to guess, I could imagine that it tries to look for "https://wss:// ws-feed.exchange.coinbase.com", which would obviously not work. I'm wondering if there is a way within the library to change the protocol that client uses. If there is, it doesn't seem to be documented. Any insights as to what's going on here would be incredibly helpful. Thanks, Noah