C++

Wasabi File Streaming Upload

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Demonstrates how to do a streaming upload from a file to the Wasabi storage service. The AWS authorization presents some difficulties when the REST request body is to be streamed from a file (or from some other source). The issue is that the SHA-256 hash of the file data must be calculated. There are only two possible ways to do this: (1) stream the file into memory in its entirety and calculate the SHA-256 hash prior to uploading, or (2) pre-calculate the SHA-256 in a streaming fashion, and then provide it to the AWS authentication object.

If the application does NOT pre-compute the SHA-256, then Chilkat (internally) is forced to stream into memory, calculate the SHA-256, and then upload from the in-memory copy of the file.

C++

#include <CkCrypt2.h>
#include <CkRest.h>
#include <CkAuthAws.h>
#include <CkStream.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    //  This first part is optional.  AWS authentication requires
    //  the SHA-256 hash of the request body (i.e. the contents of the file
    //  to be uploaded).  We can choose to pre-calculate the SHA-256 in a streaming fashion
    //  and then provide it to the authenticator object.  This way, if the file is
    //  extremely large, it never needs to completely reside in memory.
    CkCrypt2 crypt;
    //  ----------------------------------------------------
    //  Important: Wasabi requires a lowercase hex format.
    //  ----------------------------------------------------
    crypt.put_EncodingMode("hex-lower");
    crypt.put_HashAlgorithm("sha-256");
    const char *fileToUploadPath = "qa_data/xml/hamlet.xml";
    const char *hashStr = crypt.hashFileENC(fileToUploadPath);

    CkRest rest;

    //  Connect to the Amazon AWS REST server.
    bool bTls = true;
    int port = 443;
    bool bAutoReconnect = true;
    //  This example will demonstrate uploading to a bucket in the eu-west-2 region
    success = rest.Connect("s3.eu-west-2.wasabisys.com",port,bTls,bAutoReconnect);

    //  Provide AWS credentials for the REST call.
    CkAuthAws authAws;
    authAws.put_AccessKey("access-key");
    authAws.put_SecretKey("secret-key");
    authAws.put_ServiceName("s3");
    //  Provide the pre-computed SHA-256 here:
    authAws.put_PrecomputedSha256(hashStr);

    success = rest.SetAuthAws(authAws);

    rest.AddHeader("Expect","100-continue");
    rest.AddHeader("Content-Type","application/xml");

    //  Set the bucket name via the HOST header.
    //  In this case, the bucket name is "chilkat100".
    rest.put_Host("chilkat100.s3.eu-west-2.wasabisys.com");

    CkStream fileStream;
    fileStream.put_SourceFile(fileToUploadPath);

    //  Upload to the Wasabi Storage service.
    //  If the application provided the SHA-256 hash of the file contents (as shown above)
    //  then file is streamed and never has to completely reside in memory.
    //  If the application did NOT provide the SHA-256, then Chilkat will (internally) 
    //  load the entire file into memory, calculate the SHA-256, and then upload.
    const char *responseStr = rest.fullRequestStream("PUT","/hamlet.xml",fileStream);
    if (rest.get_LastMethodSuccess() != true) {
        std::cout << rest.lastErrorText() << "\r\n";
        return;
    }

    //  When successful, the Wasabi Storage service will respond with a 200 response code,
    //  with an XML body.  
    if (rest.get_ResponseStatusCode() == 200) {
        std::cout << responseStr << "\r\n";
        std::cout << "File uploaded." << "\r\n";
    }
    else {
        //  Examine the request/response to see what happened.
        std::cout << "response status code = " << rest.get_ResponseStatusCode() << "\r\n";
        std::cout << "response status text = " << rest.responseStatusText() << "\r\n";
        std::cout << "response header: " << rest.responseHeader() << "\r\n";
        std::cout << "response body: " << responseStr << "\r\n";
        std::cout << "---" << "\r\n";
        std::cout << "LastRequestStartLine: " << rest.lastRequestStartLine() << "\r\n";
        std::cout << "LastRequestHeader: " << rest.lastRequestHeader() << "\r\n";
    }
    }