C

Streaming Download Large File to the Local Filesystem

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Downloads a large file in a streaming fashion to the local filesystem. C

#include <C_CkRest.h>
#include <C_CkAuthAzureStorage.h>
#include <C_CkStream.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkRest rest;
    BOOL bTls;
    int port;
    BOOL bAutoReconnect;
    HCkAuthAzureStorage azAuth;
    int responseStatusCode;
    HCkStream bodyStream;
    const char *errResponse;

    success = FALSE;

    // Azure File Service Example: Downloads a large file to the local filesystem using a Chilkat stream.
    // See:  https://docs.microsoft.com/en-us/rest/api/storageservices/get-file

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

    rest = CkRest_Create();

    // Connect to the Azure Storage Blob Service
    bTls = TRUE;
    port = 443;
    bAutoReconnect = TRUE;
    // In this example, the storage account name is "chilkat".
    success = CkRest_Connect(rest,"chilkat.file.core.windows.net",port,bTls,bAutoReconnect);
    if (success != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        return;
    }

    // Provide Azure Cloud credentials for the REST calls.
    azAuth = CkAuthAzureStorage_Create();
    CkAuthAzureStorage_putAccessKey(azAuth,"AZURE_ACCESS_KEY");
    // The account name used here should match the 1st part of the domain passed in the call to Connect (above).
    CkAuthAzureStorage_putAccount(azAuth,"chilkat");
    CkAuthAzureStorage_putScheme(azAuth,"SharedKey");
    CkAuthAzureStorage_putService(azAuth,"File");
    // This causes the "x-ms-version: 2021-08-06" header to be automatically added.
    CkAuthAzureStorage_putXMsVersion(azAuth,"2021-08-06");
    success = CkRest_SetAuthAzureStorage(rest,azAuth);

    // Note: The application does not need to explicitly set the following
    // headers: x-ms-date, Authorization.  These headers
    // are automatically set by Chilkat.

    // When streaming a download to the local filesystem or directed elsewhere,
    // the complete HTTP GET operation must be broken into parts.
    // For example, an HTTP GET consists of sending the request, followed by reading the response header,
    // and then finally the response body.  We'll want to read the response header, and then based
    // on the information received (such as success or failure), either read the response body
    // as an error message, or as the file data.

    // Send the HTTP GET request to download the file.
    // The share is named "pip".
    success = CkRest_SendReqNoBody(rest,"GET","/pip/somethingBig.zip");
    if (success != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        CkAuthAzureStorage_Dispose(azAuth);
        return;
    }

    // Read the response header.
    responseStatusCode = CkRest_ReadResponseHeader(rest);
    if (responseStatusCode < 0) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        CkAuthAzureStorage_Dispose(azAuth);
        return;
    }

    printf("Response status code = %d\n",responseStatusCode);

    // We expect a 200 response status if the file data is coming.
    // Otherwise, we'll get a string response body with an error message(or no response body).
    if (responseStatusCode == 200) {

        bodyStream = CkStream_Create();

        // The stream's sink will be a file.
        CkStream_putSinkFile(bodyStream,"qa_output/somethingBig.zip");

        // Read the response body to the stream.  Given that we've
        // set the stream's sink to a file, it will stream directly
        // to the file.
        success = CkRest_ReadRespBodyStream(rest,bodyStream,TRUE);
        if (success != TRUE) {
            printf("%s\n",CkRest_lastErrorText(rest));
            CkRest_Dispose(rest);
            CkAuthAzureStorage_Dispose(azAuth);
            CkStream_Dispose(bodyStream);
            return;
        }

        printf("Successfully received the large file.\n");

    }
    else {
        errResponse = CkRest_readRespBodyString(rest);
        if (CkRest_getLastMethodSuccess(rest) != TRUE) {
            printf("%s\n",CkRest_lastErrorText(rest));
        }
        else {
            printf("%s\n",errResponse);
        }

    }



    CkRest_Dispose(rest);
    CkAuthAzureStorage_Dispose(azAuth);
    CkStream_Dispose(bodyStream);

    }