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(Unicode C) Firebase Receive Server-Sent Events (text/event-stream)Demonstrates how to start receiving server-sent events and update your JSON database with each event.
#include <C_CkFileAccessW.h> #include <C_CkRestW.h> #include <C_CkAuthGoogleW.h> #include <C_CkUrlW.h> #include <C_CkJsonObjectW.h> #include <C_CkStreamW.h> #include <C_CkServerSentEventW.h> #include <C_CkTaskW.h> void ChilkatSample(void) { HCkFileAccessW fac; const wchar_t *accessToken; HCkRestW rest; BOOL success; HCkAuthGoogleW authGoogle; const wchar_t *responseBody; HCkUrlW url; HCkRestW rest2; int responseStatusCode; HCkJsonObjectW jsonDb; HCkStreamW eventStream; HCkServerSentEventW sse; HCkTaskW task; int count; const wchar_t *eventStr; // Demonstrates how to begin receiving server-sent events, and to update // your JSON database for each event. // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. // This example assumes a JWT authentication token, if required, has been previously obtained. // See Get Firebase Access Token from JSON Service Account Private Key for sample code. // Load the previously obtained Firebase access token into a string. fac = CkFileAccessW_Create(); accessToken = CkFileAccessW_readEntireTextFile(fac,L"qa_data/tokens/firebaseToken.txt",L"utf-8"); if (CkFileAccessW_getLastMethodSuccess(fac) != TRUE) { wprintf(L"%s\n",CkFileAccessW_lastErrorText(fac)); CkFileAccessW_Dispose(fac); return; } rest = CkRestW_Create(); // Make the initial connection (without sending a request yet). // Once connected, any number of requests may be sent. It is not necessary to explicitly // call Connect before each request. success = CkRestW_Connect(rest,L"chilkat.firebaseio.com",443,TRUE,TRUE); if (success != TRUE) { wprintf(L"%s\n",CkRestW_lastErrorText(rest)); CkFileAccessW_Dispose(fac); CkRestW_Dispose(rest); return; } authGoogle = CkAuthGoogleW_Create(); CkAuthGoogleW_putAccessToken(authGoogle,accessToken); CkRestW_SetAuthGoogle(rest,authGoogle); CkRestW_AddHeader(rest,L"Accept",L"text/event-stream"); CkRestW_AddHeader(rest,L"Cache-Control",L"no-cache"); responseBody = CkRestW_fullRequestNoBody(rest,L"GET",L"/.json"); // A 307 redirect response is expected. if (CkRestW_getResponseStatusCode(rest) != 307) { wprintf(L"Unexpected response code: %d\n",CkRestW_getResponseStatusCode(rest)); wprintf(L"%s\n",responseBody); wprintf(L"Failed.\n"); CkFileAccessW_Dispose(fac); CkRestW_Dispose(rest); CkAuthGoogleW_Dispose(authGoogle); return; } // Get the redirect URL url = CkRestW_RedirectUrl(rest); if (CkRestW_getLastMethodSuccess(rest) != TRUE) { wprintf(L"%s\n",CkRestW_lastErrorText(rest)); CkFileAccessW_Dispose(fac); CkRestW_Dispose(rest); CkAuthGoogleW_Dispose(authGoogle); return; } wprintf(L"redirect URL domain: %s\n",CkUrlW_host(url)); wprintf(L"redirect URL path: %s\n",CkUrlW_path(url)); wprintf(L"redirect URL query params: %s\n",CkUrlW_query(url)); wprintf(L"redirect URL path with query params: %s\n",CkUrlW_pathWithQueryParams(url)); // Our text/event-stream will be obtained from the redirect URL... rest2 = CkRestW_Create(); success = CkRestW_Connect(rest2,CkUrlW_host(url),443,TRUE,TRUE); if (success != TRUE) { wprintf(L"%s\n",CkRestW_lastErrorText(rest2)); CkUrlW_Dispose(url); CkFileAccessW_Dispose(fac); CkRestW_Dispose(rest); CkAuthGoogleW_Dispose(authGoogle); CkRestW_Dispose(rest2); return; } CkRestW_AddHeader(rest2,L"Accept",L"text/event-stream"); CkRestW_AddHeader(rest2,L"Cache-Control",L"no-cache"); // Add the redirect query params to the request CkRestW_AddQueryParams(rest2,CkUrlW_query(url)); // In our case, we don't actually need the auth query param, // so remove it. CkRestW_RemoveQueryParam(rest2,L"auth"); // Send the request. (We are only sending the request here. // We are not yet getting the response because the response // will be a text/event-stream.) success = CkRestW_SendReqNoBody(rest2,L"GET",CkUrlW_path(url)); if (success != TRUE) { wprintf(L"%s\n",CkRestW_lastErrorText(rest2)); CkUrlW_Dispose(url); CkFileAccessW_Dispose(fac); CkRestW_Dispose(rest); CkAuthGoogleW_Dispose(authGoogle); CkRestW_Dispose(rest2); return; } CkUrlW_Dispose(url); // Read the response header. // We want to first get the response header to see if it's a successful // response status code. If not, then the response will not be a text/event-stream // and we should read the response body normally. responseStatusCode = CkRestW_ReadResponseHeader(rest2); if (responseStatusCode < 0) { wprintf(L"%s\n",CkRestW_lastErrorText(rest2)); CkFileAccessW_Dispose(fac); CkRestW_Dispose(rest); CkAuthGoogleW_Dispose(authGoogle); CkRestW_Dispose(rest2); return; } // If successful, a 200 response code is expected. // If the reponse code is not 200, then read the response body and fail.. if (responseStatusCode != 200) { wprintf(L"Response Code: %d\n",responseStatusCode); wprintf(L"Response Status Text: %s\n",CkRestW_responseStatusText(rest2)); wprintf(L"Response Header: %s\n",CkRestW_responseHeader(rest2)); responseBody = CkRestW_readRespBodyString(rest2); if (CkRestW_getLastMethodSuccess(rest2) == TRUE) { wprintf(L"Error Response Body: %s\n",responseBody); } wprintf(L"Failed.\n"); CkFileAccessW_Dispose(fac); CkRestW_Dispose(rest); CkAuthGoogleW_Dispose(authGoogle); CkRestW_Dispose(rest2); return; } // For this example, our JSON database will be empty at the beginning. // The incoming events (put and patch) will be applied to this database. jsonDb = CkJsonObjectW_Create(); // Make sure to set the JSON path delimiter to "/". The default is "." and this // is not compatible with Firebase paths. CkJsonObjectW_putDelimiterChar(jsonDb,L"/"); // At this point, we've received the response header. Now it's time to begin // receiving the event stream. We'll start a background thread to read the // stream. (Our main application (foreground) thread can cancel it at any time.) // While receiving in the background thread, our foreground thread can read the stream // as it desires.. eventStream = CkStreamW_Create(); // This sse object will be used as a helper to parse the server-sent event stream. sse = CkServerSentEventW_Create(); task = CkRestW_ReadRespBodyStreamAsync(rest2,eventStream,TRUE); CkTaskW_Run(task); // For this example, we'll just read a few events, and then cancel the // async task. count = 0; while ((count < 3) && (CkTaskW_getFinished(task) == FALSE)) { // Get the next event, which is a series of text lines ending with // a blank line. // Note: This method blocks the calling thread until a message arrives. // a program might instead periodically check the availability of // data via the stream's DataAvailable property, and then do the read. // An alternative to writing a while loop to read the event stream // would be to setup some sort of timer event in your program (using whatever timer functionality // is provided in a programming language/environment), to periodically check the eventStream's // DataAvailable property and consume the incoming event. eventStr = CkStreamW_readUntilMatch(eventStream,L"\r\n\r\n"); if (CkStreamW_getLastMethodSuccess(eventStream) != TRUE) { wprintf(L"%s\n",CkStreamW_lastErrorText(eventStream)); // Force the loop to exit by setting the count to a high number. count = 99999; } else { wprintf(L"Event: [%s]\n",eventStr); // We have an event. Let's update our local copy of the JSON database. success = CkServerSentEventW_LoadEvent(sse,eventStr); if (success != TRUE) { wprintf(L"Failed to load sse event: %s\n",eventStr); } else { // Now we can easily access the event name and data, and apply it to our JSON database: success = CkJsonObjectW_FirebaseApplyEvent(jsonDb,CkServerSentEventW_eventName(sse),CkServerSentEventW_data(sse)); if (success != TRUE) { wprintf(L"Failed to apply event: %s: %s\n",CkServerSentEventW_eventName(sse),CkServerSentEventW_data(sse)); } else { wprintf(L"Successfully applied event: %s: %s\n",CkServerSentEventW_eventName(sse),CkServerSentEventW_data(sse)); } } } count = count + 1; } // Make sure the background task is cancelled if still running. CkTaskW_Cancel(task); CkTaskW_Dispose(task); // Examine the JSON database after applying events.. CkJsonObjectW_putEmitCompact(jsonDb,FALSE); wprintf(L"----\n"); wprintf(L"%s\n",CkJsonObjectW_emit(jsonDb)); CkFileAccessW_Dispose(fac); CkRestW_Dispose(rest); CkAuthGoogleW_Dispose(authGoogle); CkRestW_Dispose(rest2); CkJsonObjectW_Dispose(jsonDb); CkStreamW_Dispose(eventStream); CkServerSentEventW_Dispose(sse); } |
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