(Node.js) WebSocket Send/Receive Binary Data

Demonstrates how to send and receive binary data on a websocket. This example uses Chilkat's websocket test echo server at ws://websockets.chilkat.io/wsChilkatEcho.ashx

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 sends a small JPG file (about 7KB) in a websocket frame.
    var jpgData = new chilkat.BinData();
    success = jpgData.LoadFile("qa_data/jpg/starfish.jpg");

    console.log("Number of bytes to send = " + jpgData.NumBytes);

    // Send a frame containing the JPG image data.
    // This will be the first and final frame, and therefore this constitutes the entire message.
    var finalFrame = true;
    success = ws.SendFrameBd(jpgData,finalFrame);
    if (success !== true) {
        console.log(ws.LastErrorText);
        return;
    }

    // Read the echoed binary frame(s).
    // (We sent the JPG file in a single frame, but we may receive the echo in multiple frames, but it will be one message.)
    // Read an incoming frames until we receive the final frame.
    var receivedFinalFrame = false;
    while (receivedFinalFrame == false) {

        // The ws object is accumulating the received data internally.  Once we get the final frame, we'll get the 
        // accumulated data which should constitute the entire JPG.
        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);
    }

    // Get the accumulated received data.
    var jpgReceivedData = new chilkat.BinData();
    ws.GetFrameDataBd(jpgReceivedData);
    console.log("Received " + jpgReceivedData.NumBytes + " bytes");

    // Save the received JPG to a file so we can check it..
    jpgReceivedData.WriteFile("qa_output/starfish_ws.jpg");

    // 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();