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 <C_CkWebSocket.h>
#include <C_CkRest.h>
#include <C_CkBinData.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkWebSocket ws;
    HCkRest rest;
    const char *responseBodyIgnored;
    HCkBinData jpgData;
    BOOL finalFrame;
    BOOL receivedFinalFrame;
    HCkBinData jpgReceivedData;

    success = FALSE;

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

    ws = CkWebSocket_Create();

    // 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 = CkRest_Create();
    // 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 = CkRest_Connect(rest,"websockets.chilkat.io",80,FALSE,FALSE);
    CkWebSocket_UseConnection(ws,rest);
    CkWebSocket_AddClientHeaders(ws);
    responseBodyIgnored = CkRest_fullRequestNoBody(rest,"GET","/wsChilkatEcho.ashx");
    success = CkWebSocket_ValidateServerHandshake(ws);
    if (success != TRUE) {
        printf("%s\n",CkWebSocket_lastErrorText(ws));
        CkWebSocket_Dispose(ws);
        CkRest_Dispose(rest);
        return;
    }

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

    printf("Number of bytes to send = %d\n",CkBinData_getNumBytes(jpgData));

    // Send a frame containing the JPG image data.
    // This will be the first and final frame, and therefore this constitutes the entire message.
    finalFrame = TRUE;
    success = CkWebSocket_SendFrameBd(ws,jpgData,finalFrame);
    if (success != TRUE) {
        printf("%s\n",CkWebSocket_lastErrorText(ws));
        CkWebSocket_Dispose(ws);
        CkRest_Dispose(rest);
        CkBinData_Dispose(jpgData);
        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.
    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 = CkWebSocket_ReadFrame(ws);
        if (success != TRUE) {
            printf("Failed to receive a frame\n");
            printf("ReadFrame fail reason = %d\n",CkWebSocket_getReadFrameFailReason(ws));
            printf("%s\n",CkWebSocket_lastErrorText(ws));
            CkWebSocket_Dispose(ws);
            CkRest_Dispose(rest);
            CkBinData_Dispose(jpgData);
            return;
        }

        receivedFinalFrame = CkWebSocket_getFinalFrame(ws);

        // Show the opcode and final frame bit for the frame just received:
        printf("Frame opcode: %s\n",CkWebSocket_frameOpcode(ws));
        printf("Final frame: %d\n",receivedFinalFrame);
    }

    // Get the accumulated received data.
    jpgReceivedData = CkBinData_Create();
    CkWebSocket_GetFrameDataBd(ws,jpgReceivedData);
    printf("Received %d bytes\n",CkBinData_getNumBytes(jpgReceivedData));

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

    // Close the websocket connection.
    success = CkWebSocket_SendClose(ws,TRUE,1000,"Closing this websocket.");
    if (success != TRUE) {
        printf("%s\n",CkWebSocket_lastErrorText(ws));
        CkWebSocket_Dispose(ws);
        CkRest_Dispose(rest);
        CkBinData_Dispose(jpgData);
        CkBinData_Dispose(jpgReceivedData);
        return;
    }

    // Read the Close response.
    success = CkWebSocket_ReadFrame(ws);
    if (success != TRUE) {
        printf("ReadFrame fail reason = %d\n",CkWebSocket_getReadFrameFailReason(ws));
        printf("%s\n",CkWebSocket_lastErrorText(ws));
        CkWebSocket_Dispose(ws);
        CkRest_Dispose(rest);
        CkBinData_Dispose(jpgData);
        CkBinData_Dispose(jpgReceivedData);
        return;
    }

    // Should receive the "Close" opcode.
    printf("Received opcode: %s\n",CkWebSocket_frameOpcode(ws));
    // Should be the same status code we sent (1000)
    printf("Received close status code: %d\n",CkWebSocket_getCloseStatusCode(ws));
    // The server may echo the close reason.  If not, this will be empty.
    printf("Echoed close reason: %s\n",CkWebSocket_closeReason(ws));

    printf("Success.\n");


    CkWebSocket_Dispose(ws);
    CkRest_Dispose(rest);
    CkBinData_Dispose(jpgData);
    CkBinData_Dispose(jpgReceivedData);

    }