Send and Receive WebSocket Messages

See more WebSocket Examples

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.

var success = false;

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

var ws = new CkWebSocket();

// 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 CkRest();
// 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();
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.");