Receive message on WebSocket stream

Question

Created Oct ’20

Replies 2

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Views 1.1k

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Hi, I'm using Network Framework to make a peer-to-peer connection between two devices over a WebSocket bytestream. I was wondering, should there be any special logic in my receiveMessage(completion:) code in NWConnection, since I'm using the WebSocket protocol?
Here are some snippets of my code:

Code Block swift (NWConnection)
var connection: NWConnection
let parameters = NWParameters.tls
parameters.includePeerToPeer = true
let websocketOptions = NWProtocolWebSocket.Options()
websocketOptions.autoReplyPing = true
parameters.defaultProtocolStack.applicationProtocols.insert(websocketOptions, at: 0)
let connection = NWConnection(to: endpoint, using: parameters)
startConnection()
func startConnection() {
		connection.stateUpdateHandler = { newState in
        switch newState {
				case .ready:
						log("Connection \(connection) established")
						self.receiveMessage()
				// Handle the rest
				}
}

Here's my receiveMessage code:

Code Block swiftfunc receiveMessage() {
		connection.receiveMessage { [unowned self] (content, context, isComplete, error) in
				if let error = error {
						log("Error while receiving data\(error)")
						return
				}
				if let data = content {
						didReceiveMessage(data)
						if let context?.isFinal != nil {
									didFinishReceiving()
						}
				}
				self.receiveMessage()
		}
}

Do WebSocket messages have additional metadata that I need to filter through in my receiveMessage function? Or does content already have just the data I want?

Boost

Answer 1

Systems Engineer OP

Apple

Oct ’20

I just ran through this locally and you could dig around in the NWConnection.ContentContext to see if there is anything set there for the NWProtocolWebSocket defintion.

Code Block if let responseMessage = context?.protocolMetadata(definition: NWProtocolWebSocket.definition) {
	...
}

This may give you something based on how your WebSocket is setup.

Also note the send side of this which would include adding the context that could look something like:

Code Block let message = NWProtocolWebSocket.Metadata(opcode: .text)
let context = NWConnection.ContentContext(identifier: "my_identifier", metadata: [message])

Matt Eaton
DTS Engineering, CoreOS
meaton3@apple.com

1

Answer 2

theepicapple OP

Oct ’20

Ok, I'll look into that, thanks!

0