(Node.js) Send and Receive WebSocket Messages

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.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

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

    var ws = new chilkat.WebSocket();

    // 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.

    var rest = new chilkat.Rest();
    // 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.
    var success = rest.Connect("websockets.chilkat.io",80,false,false);
    ws.UseConnection(rest);
    ws.AddClientHeaders();
    var responseBodyIgnored = rest.FullRequestNoBody("GET","/wsChilkatEcho.ashx");
    success = ws.ValidateServerHandshake();
    if (success !== true) {
        console.log(ws.LastErrorText);
        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.
    var finalFrame = false;
    success = ws.SendFrame("This is the 1st frame\r\n",finalFrame);
    if (success !== true) {
        console.log(ws.LastErrorText);
        return;
    }

    // Send the 2nd frame in the message.
    success = ws.SendFrame("This is the 2nd frame\r\n",finalFrame);
    if (success !== true) {
        console.log(ws.LastErrorText);
        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) {
        console.log(ws.LastErrorText);
        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.
    var receivedFinalFrame = false;
    while (receivedFinalFrame == false) {

        success = ws.ReadFrame();
        if (success !== true) {
            console.log("Failed to receive a frame");
            console.log("ReadFrame fail reason = " + ws.ReadFrameFailReason);
            console.log(ws.LastErrorText);
            return;
        }

        receivedFinalFrame = ws.FinalFrame;

        // Show the opcode and final frame bit for the frame just received:
        console.log("Frame opcode: " + ws.FrameOpcode);
        console.log("Final frame: " + receivedFinalFrame);
    }

    // Return the message accumulated in the above calls to ReadFrame.
    var receivedMsg = ws.GetFrameData();
    console.log("Received: " + receivedMsg);

    // Close the websocket connection.
    success = ws.SendClose(true,1000,"Closing this websocket.");
    if (success !== true) {
        console.log(ws.LastErrorText);
        return;
    }

    // Read the Close response.
    success = ws.ReadFrame();
    if (success !== true) {
        console.log("ReadFrame fail reason = " + ws.ReadFrameFailReason);
        console.log(ws.LastErrorText);
        return;
    }

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

    console.log("Success.");

}

chilkatExample();