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(Unicode C) WebSocket Send/Receive Binary DataDemonstrates 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:
#include <C_CkWebSocketW.h> #include <C_CkRestW.h> #include <C_CkBinDataW.h> void ChilkatSample(void) { HCkWebSocketW ws; HCkRestW rest; BOOL success; const wchar_t *responseBodyIgnored; HCkBinDataW jpgData; BOOL finalFrame; BOOL receivedFinalFrame; HCkBinDataW jpgReceivedData; // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. ws = CkWebSocketW_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 = CkRestW_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 = CkRestW_Connect(rest,L"websockets.chilkat.io",80,FALSE,FALSE); CkWebSocketW_UseConnection(ws,rest); CkWebSocketW_AddClientHeaders(ws); responseBodyIgnored = CkRestW_fullRequestNoBody(rest,L"GET",L"/wsChilkatEcho.ashx"); success = CkWebSocketW_ValidateServerHandshake(ws); if (success != TRUE) { wprintf(L"%s\n",CkWebSocketW_lastErrorText(ws)); CkWebSocketW_Dispose(ws); CkRestW_Dispose(rest); return; } // This example sends a small JPG file (about 7KB) in a websocket frame. jpgData = CkBinDataW_Create(); success = CkBinDataW_LoadFile(jpgData,L"qa_data/jpg/starfish.jpg"); wprintf(L"Number of bytes to send = %d\n",CkBinDataW_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 = CkWebSocketW_SendFrameBd(ws,jpgData,finalFrame); if (success != TRUE) { wprintf(L"%s\n",CkWebSocketW_lastErrorText(ws)); CkWebSocketW_Dispose(ws); CkRestW_Dispose(rest); CkBinDataW_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 = CkWebSocketW_ReadFrame(ws); if (success != TRUE) { wprintf(L"Failed to receive a frame\n"); wprintf(L"ReadFrame fail reason = %d\n",CkWebSocketW_getReadFrameFailReason(ws)); wprintf(L"%s\n",CkWebSocketW_lastErrorText(ws)); CkWebSocketW_Dispose(ws); CkRestW_Dispose(rest); CkBinDataW_Dispose(jpgData); return; } receivedFinalFrame = CkWebSocketW_getFinalFrame(ws); // Show the opcode and final frame bit for the frame just received: wprintf(L"Frame opcode: %s\n",CkWebSocketW_frameOpcode(ws)); wprintf(L"Final frame: %d\n",receivedFinalFrame); } // Get the accumulated received data. jpgReceivedData = CkBinDataW_Create(); CkWebSocketW_GetFrameDataBd(ws,jpgReceivedData); wprintf(L"Received %d bytes\n",CkBinDataW_getNumBytes(jpgReceivedData)); // Save the received JPG to a file so we can check it.. CkBinDataW_WriteFile(jpgReceivedData,L"qa_output/starfish_ws.jpg"); // Close the websocket connection. success = CkWebSocketW_SendClose(ws,TRUE,1000,L"Closing this websocket."); if (success != TRUE) { wprintf(L"%s\n",CkWebSocketW_lastErrorText(ws)); CkWebSocketW_Dispose(ws); CkRestW_Dispose(rest); CkBinDataW_Dispose(jpgData); CkBinDataW_Dispose(jpgReceivedData); return; } // Read the Close response. success = CkWebSocketW_ReadFrame(ws); if (success != TRUE) { wprintf(L"ReadFrame fail reason = %d\n",CkWebSocketW_getReadFrameFailReason(ws)); wprintf(L"%s\n",CkWebSocketW_lastErrorText(ws)); CkWebSocketW_Dispose(ws); CkRestW_Dispose(rest); CkBinDataW_Dispose(jpgData); CkBinDataW_Dispose(jpgReceivedData); return; } // Should receive the "Close" opcode. wprintf(L"Received opcode: %s\n",CkWebSocketW_frameOpcode(ws)); // Should be the same status code we sent (1000) wprintf(L"Received close status code: %d\n",CkWebSocketW_getCloseStatusCode(ws)); // The server may echo the close reason. If not, this will be empty. wprintf(L"Echoed close reason: %s\n",CkWebSocketW_closeReason(ws)); wprintf(L"Success.\n"); CkWebSocketW_Dispose(ws); CkRestW_Dispose(rest); CkBinDataW_Dispose(jpgData); CkBinDataW_Dispose(jpgReceivedData); } |
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