C++

WebSocket Send/Receive Binary Data

See more WebSocket Examples

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.

C++

#include <CkWebSocket.h>
#include <CkRest.h>
#include <CkBinData.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    CkWebSocket ws;

    // 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.

    CkRest 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.
    success = rest.Connect("websockets.chilkat.io",80,false,false);
    ws.UseConnection(rest);
    ws.AddClientHeaders();
    const char *responseBodyIgnored = rest.fullRequestNoBody("GET","/wsChilkatEcho.ashx");
    success = ws.ValidateServerHandshake();
    if (success != true) {
        std::cout << ws.lastErrorText() << "\r\n";
        return;
    }

    // This example sends a small JPG file (about 7KB) in a websocket frame.
    CkBinData jpgData;
    success = jpgData.LoadFile("qa_data/jpg/starfish.jpg");

    std::cout << "Number of bytes to send = " << jpgData.get_NumBytes() << "\r\n";

    // Send a frame containing the JPG image data.
    // This will be the first and final frame, and therefore this constitutes the entire message.
    bool finalFrame = true;
    success = ws.SendFrameBd(jpgData,finalFrame);
    if (success != true) {
        std::cout << ws.lastErrorText() << "\r\n";
        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.
    bool 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) {
            std::cout << "Failed to receive a frame" << "\r\n";
            std::cout << "ReadFrame fail reason = " << ws.get_ReadFrameFailReason() << "\r\n";
            std::cout << ws.lastErrorText() << "\r\n";
            return;
        }

        receivedFinalFrame = ws.get_FinalFrame();

        // Show the opcode and final frame bit for the frame just received:
        std::cout << "Frame opcode: " << ws.frameOpcode() << "\r\n";
        std::cout << "Final frame: " << receivedFinalFrame << "\r\n";
    }

    // Get the accumulated received data.
    CkBinData jpgReceivedData;
    ws.GetFrameDataBd(jpgReceivedData);
    std::cout << "Received " << jpgReceivedData.get_NumBytes() << " bytes" << "\r\n";

    // 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) {
        std::cout << ws.lastErrorText() << "\r\n";
        return;
    }

    // Read the Close response.
    success = ws.ReadFrame();
    if (success != true) {
        std::cout << "ReadFrame fail reason = " << ws.get_ReadFrameFailReason() << "\r\n";
        std::cout << ws.lastErrorText() << "\r\n";
        return;
    }

    // Should receive the "Close" opcode.
    std::cout << "Received opcode: " << ws.frameOpcode() << "\r\n";
    // Should be the same status code we sent (1000)
    std::cout << "Received close status code: " << ws.get_CloseStatusCode() << "\r\n";
    // The server may echo the close reason.  If not, this will be empty.
    std::cout << "Echoed close reason: " << ws.closeReason() << "\r\n";

    std::cout << "Success." << "\r\n";
    }