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(Unicode C) Send and Receive WebSocket MessagesThis example how to send and receive websocket messages. 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:
#include <C_CkWebSocketW.h> #include <C_CkRestW.h> void ChilkatSample(void) { HCkWebSocketW ws; HCkRestW rest; BOOL success; const wchar_t *responseBodyIgnored; BOOL finalFrame; BOOL receivedFinalFrame; const wchar_t *receivedMsg; // 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 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. finalFrame = FALSE; success = CkWebSocketW_SendFrame(ws,L"This is the 1st frame\r\n",finalFrame); if (success != TRUE) { wprintf(L"%s\n",CkWebSocketW_lastErrorText(ws)); CkWebSocketW_Dispose(ws); CkRestW_Dispose(rest); return; } // Send the 2nd frame in the message. success = CkWebSocketW_SendFrame(ws,L"This is the 2nd frame\r\n",finalFrame); if (success != TRUE) { wprintf(L"%s\n",CkWebSocketW_lastErrorText(ws)); CkWebSocketW_Dispose(ws); CkRestW_Dispose(rest); return; } // Send the 3rd and final frame in the message. finalFrame = TRUE; success = CkWebSocketW_SendFrame(ws,L"This is the 3rd frame\r\n",finalFrame); if (success != TRUE) { wprintf(L"%s\n",CkWebSocketW_lastErrorText(ws)); CkWebSocketW_Dispose(ws); CkRestW_Dispose(rest); 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. receivedFinalFrame = FALSE; while (receivedFinalFrame == FALSE) { 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); 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); } // Return the message accumulated in the above calls to ReadFrame. receivedMsg = CkWebSocketW_getFrameData(ws); wprintf(L"Received: %s\n",receivedMsg); // 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); 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); 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); } |
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