Go

Send and Receive WebSocket Messages

See more WebSocket Examples

This example how to send and receive websocket messages.

A WebSocket message can be composed of one or more frames. The simple case is where a single frame is both the first and last frame in a message. This is the case where the 1st frame in the message has the "final frame" bit set.

This example demonstrates sending and receiving multi-frame messages.

Note: The websockets.chilkat.io server imposes the following limitations:
Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.

Go

    success := false

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    ws := chilkat.NewWebSocket()

    // For brevity, this example does not check for errors when etablishing the WebSocket connection.
    // See Establish WebSocket Connection for more complete sample code for making the connection.

    rest := chilkat.NewRest()
    // Connect to websockets.chilkat.io
    // IMPORTANT: websockets.chilkat.io accepts frames of up to 16K in size and echoes them back.
    // IMPORTANT: The websockets.chilkat.io server imposes the following limitations: 
    // ---------- Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.
    success = rest.Connect("websockets.chilkat.io",80,false,false)
    ws.UseConnection(rest)
    ws.AddClientHeaders()
    responseBodyIgnored := rest.FullRequestNoBody("GET","/wsChilkatEcho.ashx")
    success = ws.ValidateServerHandshake()
    if success != true {
        fmt.Println(ws.LastErrorText())
        ws.DisposeWebSocket()
        rest.DisposeRest()
        return
    }

    // This example demonstrates sending and receiving a multi-frame message.

    // The websocket message will be composed of three text lines, each frame will contain a single line.

    // Send the 1st frame in the message.
    finalFrame := false
    success = ws.SendFrame("This is the 1st frame\r\n",finalFrame)
    if success != true {
        fmt.Println(ws.LastErrorText())
        ws.DisposeWebSocket()
        rest.DisposeRest()
        return
    }

    // Send the 2nd frame in the message.
    success = ws.SendFrame("This is the 2nd frame\r\n",finalFrame)
    if success != true {
        fmt.Println(ws.LastErrorText())
        ws.DisposeWebSocket()
        rest.DisposeRest()
        return
    }

    // Send the 3rd and final frame in the message.
    finalFrame = true
    success = ws.SendFrame("This is the 3rd frame\r\n",finalFrame)
    if success != true {
        fmt.Println(ws.LastErrorText())
        ws.DisposeWebSocket()
        rest.DisposeRest()
        return
    }

    // Read an incoming frames until we receive the final frame.
    // Note: It may be that the echo server (websockets.chilkat.io) responds with 
    // the full message in a single final frame.
    receivedFinalFrame := false
    for receivedFinalFrame == false {

        success = ws.ReadFrame()
        if success != true {
            fmt.Println("Failed to receive a frame")
            fmt.Println("ReadFrame fail reason = ", ws.ReadFrameFailReason())
            fmt.Println(ws.LastErrorText())
            ws.DisposeWebSocket()
            rest.DisposeRest()
            return
        }

        receivedFinalFrame = ws.FinalFrame()

        // Show the opcode and final frame bit for the frame just received:
        fmt.Println("Frame opcode: ", ws.FrameOpcode())
        fmt.Println("Final frame: ", receivedFinalFrame)
    }

    // Return the message accumulated in the above calls to ReadFrame.
    receivedMsg := ws.GetFrameData()
    fmt.Println("Received: ", *receivedMsg)

    // Close the websocket connection.
    success = ws.SendClose(true,1000,"Closing this websocket.")
    if success != true {
        fmt.Println(ws.LastErrorText())
        ws.DisposeWebSocket()
        rest.DisposeRest()
        return
    }

    // Read the Close response.
    success = ws.ReadFrame()
    if success != true {
        fmt.Println("ReadFrame fail reason = ", ws.ReadFrameFailReason())
        fmt.Println(ws.LastErrorText())
        ws.DisposeWebSocket()
        rest.DisposeRest()
        return
    }

    // Should receive the "Close" opcode.
    fmt.Println("Received opcode: ", ws.FrameOpcode())
    // Should be the same status code we sent (1000)
    fmt.Println("Received close status code: ", ws.CloseStatusCode())
    // The server may echo the close reason.  If not, this will be empty.
    fmt.Println("Echoed close reason: ", ws.CloseReason())

    fmt.Println("Success.")

    ws.DisposeWebSocket()
    rest.DisposeRest()