websocket

websocket is a minimal and idiomatic WebSocket library for Go.

This library is not final and the API is subject to change.

Install

go get nhooyr.io/[email protected]

Features

• Minimal and idiomatic API
• Tiny codebase at 1400 lines
• First class context.Context support
• Thorough tests, fully passes the autobahn-testsuite
• Zero dependencies outside of the stdlib for the core library
• JSON and ProtoBuf helpers in the wsjson and wspb subpackages
• High performance
• Concurrent writes

Roadmap

• WebSockets over HTTP/2 #4
• Deflate extension support #5

Examples

For a production quality example that shows off the full API, see the echo example on the godoc. On github, the example is at example_echo_test.go.

Server

http.HandlerFunc(func (w http.ResponseWriter, r *http.Request) {
	c, err := websocket.Accept(w, r, websocket.AcceptOptions{})
	if err != nil {
		// ...
	}
	defer c.Close(websocket.StatusInternalError, "the sky is falling")

	ctx, cancel := context.WithTimeout(r.Context(), time.Second*10)
	defer cancel()
	
	var v interface{}
	err = wsjson.Read(ctx, c, &v)
	if err != nil {
		// ...
	}
	
	log.Printf("received: %v", v)
	
	c.Close(websocket.StatusNormalClosure, "")
})

Client

The client side of this library requires at minimum Go 1.12 as it uses a new feature in net/http to perform WebSocket handshakes.

ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
defer cancel()

c, _, err := websocket.Dial(ctx, "ws://localhost:8080", websocket.DialOptions{})
if err != nil {
	// ...
}
defer c.Close(websocket.StatusInternalError, "the sky is falling")

err = wsjson.Write(ctx, c, "hi")
if err != nil {
	// ...
}

c.Close(websocket.StatusNormalClosure, "")

Design justifications

• A minimal API is easier to maintain due to less docs, tests and bugs
• A minimal API is also easier to use and learn
• Context based cancellation is more ergonomic and robust than setting deadlines
• No ping support because TCP keep alives work fine for HTTP/1.1 and they do not make sense with HTTP/2 (see #1)
• net.Conn is never exposed as WebSocket over HTTP/2 will not have a net.Conn.
• Using net/http's Client for dialing means we do not have to reinvent dialing hooks and configurations like other WebSocket libraries

Comparison

Before the comparison, I want to point out that both gorilla/websocket and gobwas/ws were extremely useful in implementing the WebSocket protocol correctly so big thanks to the authors of both. In particular, I made sure to go through the issue tracker of gorilla/websocket to ensure I implemented details correctly and understood how people were using WebSockets in production.

gorilla/websocket

https://github.com/gorilla/websocket

This package is the community standard but it is 6 years old and over time has accumulated cruft. There are too many ways to do the same thing. Just compare the godoc of nhooyr/websocket side by side with gorilla/websocket.

The API for nhooyr/websocket has been designed such that there is only one way to do things which makes it easy to use correctly. Not only is the API simpler, the implementation is only 1400 lines whereas gorilla/websocket is at 3500 lines. That's more code to maintain, more code to test, more code to document and more surface area for bugs.

The future of gorilla/websocket is also uncertain. See gorilla/websocket#370.

Pure conjecture but I would argue that the sprawling API has made it difficult to maintain.

Moreover, nhooyr/websocket has support for newer Go idioms such as context.Context and also uses net/http's Client and ResponseWriter directly for WebSocket handshakes. gorilla/websocket writes its handshakes to the underlying net.Conn which means it has to reinvent hooks for TLS and proxies and prevents support of HTTP/2.

Some more advantages of nhooyr/websocket are that it supports concurrent writes and makes it very easy to close the connection with a status code and reason.

In terms of performance, there is no significant difference between the two. Will update with benchmarks soon (#75).

x/net/websocket

https://godoc.org/golang.org/x/net/websocket

Unmaintained and the API does not reflect WebSocket semantics. Should never be used.

See golang/go#18152

gobwas/ws

https://github.com/gobwas/ws

This library has an extremely flexible API but that comes at the cost of usability and clarity.

This library is fantastic in terms of performance. The author put in significant effort to ensure its speed and I have applied as many of its optimizations as I could into nhooyr/websocket. Definitely check out his fantastic blog post about performant WebSocket servers.

If you want a library that gives you absolute control over everything, this is the library, but for most users, the API provided by nhooyr/websocket will fit better as it is nearly just as performant but much easier to use correctly and idiomatic.