NIOWebSocketClient with arguments

I've downloaded NIOWebSocketClient and NIOWebSocketServer and copied each into Swift Packages on a Pi running 64bit BullsEye. They compile and run together perfectly on the same machine when using the default run arguments, but not when given a hostname and port. For example...

pi@rp64lite:~/NIOWebSocketClient $ swift run NIOWebSocketClient rp64lite.local 8888
[0/0] Build complete!
Establishing connection.
HTTP handler removed.
Swift/ErrorType.swift:200: Fatal error: Error raised at top level: NIOPosix.NIOConnectionError(host: "rp64lite.local", port: 8888, dnsAError: nil, dnsAAAAError: nil, connectionErrors: [NIOPosix.SingleConnectionFailure(target: [IPv4]rp64lite.local/192.168.1.38:8888, error: connection reset (error set): Connection refused (errno: 111))])
Current stack trace:
0    libswiftCore.so                    0x0000007fb9d3c744 swift_reportError + 64
1    libswiftCore.so                    0x0000007fb9dad1cc _swift_stdlib_reportFatalErrorInFile + 124
2    libswiftCore.so                    0x0000007fb9aea718 _assertionFailure(_:_:file:line:flags:) + 296
3    libswiftCore.so                    0x0000007fb9b4ae7c swift_errorInMain + 516
4    NIOWebSocketClient                 0x000000557d1fcfd0 <unavailable> + 2609104
5    libc.so.6                          0x0000007fb95f5130 __libc_start_main + 232
6    NIOWebSocketClient                 0x000000557cfc6254 <unavailable> + 287316
Trace/breakpoint trap

I've tried using the ip6 address instead, but get a similar result. Please can someone tell me what I should be doing?

Ultimately, I want to connect to an external service that only requires a domain/path address (without a port number).

OK. I've found the answer is to get the server running in ip4 - like this...

pi@rp64lite:~/NIOWebSocketServer $ swift run NIOWebSocketServer 0.0.0.0 8888

But I'm still left wondering how to connect NIOWebSocketClient to the external server that doesn't expect me to send a port number.

(Paintext) HTTP runs over port 80 by default and WebSocket is usually upgraded from HTTP(S). So if you have a public server that speaks plaintext WebSocket (ws://...) then you can just put port 80 there. I will say that today, server (hopefully) don't speak plaintext HTTP anymore. They speak HTTPS and upgrade WebSocket from there (wss://..., note the extra s).

NIOWebSocketClient however is just a demo how to use NIO's WebSocket handlers. If you want to speak WebSocket over TLS (wss://...) as you should, then you'd need to combine that with a TLS implementation such as swift-nio-ssl or swift-nio-transport-services (which on Apple platforms lets Network.framework to the networking & TLS).

I will say that if you just want to use WebSocket, then NIO* is the wrong tool, it's way too low-level for what you're trying to do. I would recommend Vapor's websocket-kit if you want to use a WebSocket. It will do all the NIO & TLS bits for you.

Of course, if you're looking into NIOWebSocket for educational reasons or you want to create your own WebSocket library, then go ahead :slight_smile: .

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