How to register a new websocket connection with gooptic

php Xiaobian Yuzai will introduce you how to register a new websocket connection with gooptic. GoOptic is an open source Go language websocket library for building high-performance, real-time communication applications. To register a new websocket connection, you first need to import the GoOptic library in your Go program. You can then use the functions provided by GoOptic to create a websocket server and specify the address and port to listen on. Next, you can use the HandleFunc function provided by GoOptic to handle various events of the websocket connection, such as receiving messages, sending messages, etc. Finally, call the Serve function provided by GoOptic to start the websocket server so that it can accept new connections. With these steps, you can successfully register a new websocket connection with gooptic.

Question content

I'm trying to set up a simple websocket server that should serve some content to the client at unknown intervals.

My code currently looks like this:

router.go

func setuproutes(app *fiber.app) error {

    app.get("/whop/validate", handler.handlewhopvalidate)
    /*other non-websocket routes*/

    /*...*/

    app.get("/ws/monitor", websocket.new(wshandler.handlewsmonitor))

    app.use(func(c *fiber.ctx) error {
        c.sendstatus(404)
        return c.next()
    })

    return nil
}

handler.go

package handlers

import (
    "fmt"
    "log"

    "github.com/gofiber/websocket/v2"
)

var register = make(chan *websocket.conn)
var unregister = make(chan *websocket.conn)

func handlewsmonitor(c *websocket.conn) {
    go socketlistener()
    defer func() {
        unregister <- c
        //may need to check whether connection is already closed before re-closing?
        c.close()
    }()
    //sends conn into channel
    register <- c
    for {
        messagetype, message, err := c.readmessage()
        if err != nil {
            if websocket.isunexpectedcloseerror(err, websocket.closegoingaway, websocket.closeabnormalclosure) {
                log.println("read error:", err)
            }
            return
        }
        if messagetype == websocket.textmessage {
            log.println("got textmessage:", string(message))
        } else {
            log.println("received message of type:", messagetype)
        }
    }
}

func socketlistener() {
    for {
        select {
        case c := <-register:
            messagetype, message, err := c.readmessage()
            if err != nil {
                log.println(err)
                unregister <- c
                return
            }

            fmt.printf("got message of type: %d\nmessage:%s\n", messagetype, string(message))
            fmt.printf("connection params: %s\n", c.params("id"))
            //append to list of co
        case c := <-unregister:
            //remove conection from list of clients
            c.close()
            fmt.printf("closed connection\n")

        }

    }
}

The problem I'm having is that when I connect to the websocket, my registration select case is missing (I want to register the client connection to the map using the uuid previously provided to the client).

client.go

package main

import (
    "flag"
    "log"
    "net/url"

    "github.com/fasthttp/websocket"
)

type Client struct {
    C *websocket.Conn
}

func main() {
    addr := flag.String("addr", "localhost:8080", "http service address")
    u := url.URL{
        Scheme:   "ws",
        Host:     *addr,
        Path:     "/ws/monitor",
        RawQuery: "id=12",
    }
    wsClient := &Client{}

    log.Printf("connecting to %s\n", u.String())
    // Connect to the WebSocket server
    conn, resp, err := websocket.DefaultDialer.Dial(u.String(), nil)
    if err != nil {
        log.Fatal("Dial:", err)
    }
    wsClient.C = conn
    if resp != nil {
        log.Println("Got response:", resp)
    }
    defer wsClient.closeConn()
}

func (client *Client) closeConn() {
    err := client.C.WriteMessage(
        websocket.CloseMessage,
        websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""),
    )
    if err != nil {
        log.Println("Write close:", err)
        return
    }
    client.C.Close()
    log.Println("Connection closed")
}

Is there something missing in

handler.go or should I take a different approach when connecting to the server using the client?

Workaround

According to my testing, the register's select case does hit (the code I used is attached at the bottom of this answer).

But I found other problems in the code:

1. unregister chan is unbuffered, unregister <- c​​ in socketlistener will be blocked. When the code reaches unregister <- c​​, a deadlock occurs between it and case c := <-unregister.
2. It seems that our entire server only needs one socketlistener goroutine. If this is the case, it should be moved outside handlewsmonitor.
3. handlewsmonitor and socketlistener both read from the connection. What are the responsibilities of socketlistener? It seems it shouldn't read from the connection.

Thinking about it again, it seems that you can add and delete connections directly on the map in handlewsmonitor. socketlistener can be completely deleted. Simplicity should be a key goal of design. See kiss principles.

package main

import (
    "log"

    "github.com/gofiber/fiber/v2"
    "github.com/gofiber/websocket/v2"
)

var (
    register   = make(chan *websocket.Conn)
    unregister = make(chan *websocket.Conn)
)

func main() {
    // Make it easy to find out which line prints the log.
    log.SetFlags(log.Lshortfile)
    app := fiber.New()

    app.Get("/ws/monitor", websocket.New(HandleWsMonitor))

    log.Fatal(app.Listen(":8080"))
}

func HandleWsMonitor(c *websocket.Conn) {
    // It seems the we only need one SocketListener goroutine for the whole server.
    // If this is the case, the next line should be moved outside of this func.
    go SocketListener()
    defer func() {
        unregister <- c
        c.Close()
    }()

    register <- c
    for {
        messageType, message, err := c.ReadMessage()
        if err != nil {
            if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
                log.Println("read error:", err)
            }
            return
        }
        if messageType == websocket.TextMessage {
            log.Println("got textmessage:", string(message))
        } else {
            log.Println("received message of type:", messageType)
        }
    }
}

func SocketListener() {
    for {
        select {
        case c := <-register:
            // This did appear in the log.
            log.Println("case c := <-register")
            messageType, message, err := c.ReadMessage()
            if err != nil {
                log.Println(err)
                // unregister is unbuffered, the sending will be blocked.
                unregister <- c
                // If we use only one SocketListener goroutine then it should
                // not return here.
                return
            }

            log.Printf("Got message of type: %d\nMessage:%s\n", messageType, string(message))
            log.Printf("Connection Params: %s\n", c.Params("id"))
        case c := <-unregister:
            c.Close()
            log.Println("Closed connection")

        }
    }
}

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