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Introduction

GWS (Go WebSocket) is a very simple, fast, reliable and feature-rich WebSocket implementation written in Go. It is designed to be used in highly-concurrent environments, and it is suitable for building API, Proxy, Game, Live Video, Message, etc. It supports both server and client side with a simple API which mean you can easily write a server or client by yourself.

GWS developed base on Event-Driven model. every connection has a goroutine to handle the event, and the event is able to be processed in a non-blocking way.

Why GWS

• <font size=3>Simplicity and Ease of Use</font>

  • User-Friendly: Simple and clear WebSocket Event API design makes server-client interaction easy.
  • Code Efficiency: Minimizes the amount of code needed to implement complex WebSocket solutions.

• <font size=3>High-Performance</font>

  • High IOPS Low Latency: Designed for rapid data transmission and reception, ideal for time-sensitive applications.
  • Low Memory Usage: Highly optimized memory multiplexing system to minimize memory usage and reduce your cost of ownership.

• <font size=3>Reliability and Stability</font>

  • Robust Error Handling: Advanced mechanisms to manage and mitigate errors, ensuring continuous operation.
  • Well-Developed Test Cases: Passed all Autobahn test cases, fully compliant with RFC 7692. Unit test coverage is almost 100%, covering all conditional branches.

Benchmark

IOPS (Echo Server)

GOMAXPROCS=4, Connection=1000, CompressEnabled=false

GoBench

go test -benchmem -run=^$ -bench . github.com/lxzan/gws
goos: linux
goarch: amd64
pkg: github.com/lxzan/gws
cpu: AMD Ryzen 5 PRO 4650G with Radeon Graphics
BenchmarkConn_WriteMessage/compress_disabled-12                  5263632               232.3 ns/op            24 B/op          1 allocs/op
BenchmarkConn_WriteMessage/compress_enabled-12                     99663             11265 ns/op             386 B/op          1 allocs/op
BenchmarkConn_ReadMessage/compress_disabled-12                   7809654               152.4 ns/op             8 B/op          0 allocs/op
BenchmarkConn_ReadMessage/compress_enabled-12                     326257              3133 ns/op              81 B/op          1 allocs/op 
PASS
ok      github.com/lxzan/gws    17.231s

Index

• Introduction
• Why GWS
• Benchmark
  • IOPS (Echo Server)
  • GoBench
• Index
• Feature
• Attention
• Install
• Event
• Quick Start
• Best Practice
• More Examples
  • KCP
  • Proxy
  • Broadcast
  • WriteWithTimeout
  • Pub / Sub
• Autobahn Test
• Communication
• Buy me a coffee
• Acknowledgments

Feature

• Event API
• Broadcast
• Dial via Proxy
• Context-Takeover
• Concurrent & Asynchronous Non-Blocking Write
• Segmented Writing of Large Files
• Passed Autobahn Test Cases Server / Client

Attention

• The errors returned by the gws.Conn export methods are ignorable, and are handled internally.
• Transferring large files with gws tends to block the connection.
• If HTTP Server is reused, it is recommended to enable goroutine, as blocking will prevent the context from being GC.

Install

go get -v github.com/lxzan/gws@latest

Event

type Event interface {
    OnOpen(socket *Conn)                        // connection is established
    OnClose(socket *Conn, err error)            // received a close frame or input/output error occurs
    OnPing(socket *Conn, payload []byte)        // received a ping frame
    OnPong(socket *Conn, payload []byte)        // received a pong frame
    OnMessage(socket *Conn, message *Message)   // received a text/binary frame
}

Quick Start

package main

import "github.com/lxzan/gws"

func main() {
	gws.NewServer(&gws.BuiltinEventHandler{}, nil).Run(":6666")
}

Best Practice

package main

import (
	"github.com/lxzan/gws"
	"net/http"
	"time"
)

const (
	PingInterval = 5 * time.Second
	PingWait     = 10 * time.Second
)

func main() {
	upgrader := gws.NewUpgrader(&Handler{}, &gws.ServerOption{
		ParallelEnabled:  true,                                 // Parallel message processing
		Recovery:          gws.Recovery,                         // Exception recovery
		PermessageDeflate: gws.PermessageDeflate{Enabled: true}, // Enable compression
	})
	http.HandleFunc("/connect", func(writer http.ResponseWriter, request *http.Request) {
		socket, err := upgrader.Upgrade(writer, request)
		if err != nil {
			return
		}
		go func() {
			socket.ReadLoop() // Blocking prevents the context from being GC.
		}()
	})
	http.ListenAndServe(":6666", nil)
}

type Handler struct{}

func (c *Handler) OnOpen(socket *gws.Conn) {
	_ = socket.SetDeadline(time.Now().Add(PingInterval + PingWait))
}

func (c *Handler) OnClose(socket *gws.Conn, err error) {}

func (c *Handler) OnPing(socket *gws.Conn, payload []byte) {
	_ = socket.SetDeadline(time.Now().Add(PingInterval + PingWait))
	_ = socket.WritePong(nil)
}

func (c *Handler) OnPong(socket *gws.Conn, payload []byte) {}

func (c *Handler) OnMessage(socket *gws.Conn, message *gws.Message) {
	defer message.Close()
	socket.WriteMessage(message.Opcode, message.Bytes())
}

More Examples

KCP

• server

package main

import (
	"log"
	"github.com/lxzan/gws"
	kcp "github.com/xtaci/kcp-go"
)

func main() {
	listener, err := kcp.Listen(":6666")
	if err != nil {
		log.Println(err.Error())
		return
	}
	app := gws.NewServer(&gws.BuiltinEventHandler{}, nil)
	app.RunListener(listener)
}

• client

package main

import (
	"github.com/lxzan/gws"
	kcp "github.com/xtaci/kcp-go"
	"log"
)

func main() {
	conn, err := kcp.Dial("127.0.0.1:6666")
	if err != nil {
		log.Println(err.Error())
		return
	}
	app, _, err := gws.NewClientFromConn(&gws.BuiltinEventHandler{}, nil, conn)
	if err != nil {
		log.Println(err.Error())
		return
	}
	app.ReadLoop()
}

Proxy

Dial via proxy, using socks5 protocol.

package main

import (
	"crypto/tls"
	"github.com/lxzan/gws"
	"golang.org/x/net/proxy"
	"log"
)

func main() {
	socket, _, err := gws.NewClient(new(gws.BuiltinEventHandler), &gws.ClientOption{
		Addr:      "wss://example.com/connect",
		TlsConfig: &tls.Config{InsecureSkipVerify: true},
		NewDialer: func() (gws.Dialer, error) {
			return proxy.SOCKS5("tcp", "127.0.0.1:1080", nil, nil)
		},
		PermessageDeflate: gws.PermessageDeflate{
			Enabled:               true,
			ServerContextTakeover: true,
			ClientContextTakeover: true,
		},
	})
	if err != nil {
		log.Println(err.Error())
		return
	}
	socket.ReadLoop()
}

Broadcast

Create a Broadcaster instance, call the Broadcast method in a loop to send messages to each client, and close the broadcaster to reclaim memory. The message is compressed only once.

func Broadcast(conns []*gws.Conn, opcode gws.Opcode, payload []byte) {
    var b = gws.NewBroadcaster(opcode, payload)
    defer b.Close()
    for _, item := range conns {
        _ = b.Broadcast(item)
    }
}

WriteWithTimeout

SetDeadline covers most of the scenarios, but if you want to control the timeout for each write, you need to encapsulate the WriteWithTimeout function, the creation and destruction of the timer will incur some overhead.

func WriteWithTimeout(socket *gws.Conn, p []byte, timeout time.Duration) error {
	var sig = atomic.Uint32{}
	var timer = time.AfterFunc(timeout, func() {
		if sig.CompareAndSwap(0, 1) {
			socket.WriteClose(1000, []byte("write timeout"))
		}
	})
	var err = socket.WriteMessage(gws.OpcodeText, p)
	if sig.CompareAndSwap(0, 1) {
		timer.Stop()
	}
	return err
}

Pub / Sub

Use the event_emitter package to implement the publish-subscribe model. Wrap gws.Conn in a structure and implement the GetSubscriberID method to get the subscription ID, which must be unique. The subscription ID is used to identify the subscriber, who can only receive messages on the subject of his subscription.

This example is useful for building chat rooms or push messages using gws. This means that a user can subscribe to one or more topics via websocket, and when a message is posted to that topic, all subscribers will receive the message.

package main

import (
    "github.com/lxzan/event_emitter"
    "github.com/lxzan/gws"
)

type Subscriber gws.Conn

func NewSubscriber(conn *gws.Conn) *Subscriber { return (*Subscriber)(conn) }

func (c *Subscriber) GetSubscriberID() int64 {
    userId, _ := c.GetMetadata().Load("userId")
    return userId.(int64)
}

func (c *Subscriber) GetMetadata() event_emitter.Metadata { return c.Conn().Session() }

func (c *Subscriber) Conn() *gws.Conn { return (*gws.Conn)(c) }

func Subscribe(em *event_emitter.EventEmitter[int64, *Subscriber], s *Subscriber, topic string) {
    em.Subscribe(s, topic, func(msg any) {
        _ = msg.(*gws.Broadcaster).Broadcast(s.Conn())
    })
}

func Publish(em *event_emitter.EventEmitter[int64, *Subscriber], topic string, msg []byte) {
    var broadcaster = gws.NewBroadcaster(gws.OpcodeText, msg)
    defer broadcaster.Close()
    em.Publish(topic, broadcaster)
}

Autobahn Test

cd examples/autobahn
mkdir reports
docker run -it --rm \
    -v ${PWD}/config:/config \
    -v ${PWD}/reports:/reports \
    crossbario/autobahn-testsuite \
    wstest -m fuzzingclient -s /config/fuzzingclient.json

Communication

微信需要先添加好友再拉群, 请注明来自 GitHub

Buy me a coffee

Acknowledgments

The following project had particular influence on gws's design.

• crossbario/autobahn-testsuite
• klauspost/compress
• lesismal/nbio