(Unicode C++) S3 Upload the Parts for a Multipart Upload

This example uploads a large file in parts. The multipart upload needs to have been first initiated prior to uploading the parts.

See http://docs.aws.amazon.com/AmazonS3/latest/API/mpUploadUploadPart.html for more information about uploading parts.

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#include <CkXmlW.h>
#include <CkFileAccessW.h>
#include <CkRestW.h>
#include <CkAuthAwsW.h>
#include <CkStringBuilderW.h>
#include <CkStreamW.h>

void ChilkatSample(void)
    {
    // In the 1st step for uploading a large file, the multipart upload was initiated
    // as shown here: Initiate Multipart Upload

    // Other S3 Multipart Upload Examples:
    // Complete Multipart Upload
    // Abort Multipart Upload
    // List Parts

    // When we initiated the multipart upload, we saved the XML response to a file.  This
    // XML response contains the UploadId.  We'll begin by loading that XML and getting
    // the Upload ID.

    CkXmlW xmlInit;
    bool success = xmlInit.LoadXmlFile(L"s3_multipart_uploads/initiate.xml");
    if (success != true) {
        wprintf(L"Did not find the initiate.xml XML file.\n");
        return;
    }

    const wchar_t *uploadId = xmlInit.getChildContent(L"UploadId");
    wprintf(L"UploadId = %s\n",uploadId);

    // When uploading parts, we need to keep an XML record of each part number
    // and its corresponding ETag, which is received in the response for each part.
    // There can be up to 10000 parts, numbered 1 to 10000.  
    // After all parts have been uploaded, the final step will be to complete
    // the multipart upload (see Complete Multipart Upload)

    // In this example, the large file we want to upload is somethingBig.zip
    const wchar_t *fileToUploadPath = L"s3_multipart_uploads/somethingBig.zip";

    // The minimum allowed part size is 5MB (5242880 bytes).  The last part can be smaller because
    // it will contain the remainder of the file.  (This minimum is enforced by the AWS service.)
    // We'll use the minimum allowed part size for this example.
    int partSize = 5242880;

    // Let's use Chilkat's FileAccess API to examine the file to be uploaded.  We'll get the size
    // of the file and find out how many parts will be needed, including the final "partial" part.
    CkFileAccessW fac;
    fac.OpenForRead(fileToUploadPath);

    // How many parts will there be if each part is 5242880 bytes?
    int numParts = fac.GetNumBlocks(partSize);
    wprintf(L"numParts = %d\n",numParts);
    fac.FileClose();

    // Imagine that we may be running this for the 1st time, or maybe we already
    // attempted to upload parts, and something failed. Maybe there was a network problem
    // the resulted in not all parts getting uploaded.  We'll write this code so that if run again,
    // it will upload whatever parts haven't yet been uploaded.

    // We'll keep a partsList.xml file to record the parts that have already been successfully
    // uploaded.  If this file does not yet exist, we'll create it..
    const wchar_t *partsListFile = L"s3_multipart_uploads/partsList.xml";
    CkXmlW partsListXml;
    if (fac.FileExists(partsListFile) == true) {
        partsListXml.LoadXmlFile(partsListFile);
    }

    // Make sure the top-level tag is "CompleteMultipartUpload"
    partsListXml.put_Tag(L"CompleteMultipartUpload");

    // --------------------------------------
    // Before entering the loop to upload parts,
    // setup the REST object with AWS authentication,
    // and make the initial connection.
    CkRestW rest;

    // Connect to the Amazon AWS REST server.
    bool bTls = true;
    int port = 443;
    bool bAutoReconnect = true;
    success = rest.Connect(L"s3.amazonaws.com",port,bTls,bAutoReconnect);

    // ----------------------------------------------------------------------------
    // Important: For buckets created in regions outside us-east-1,
    // there are three important changes that need to be made.
    // See Working with S3 Buckets in Non-us-east-1 Regions for the details.
    // ----------------------------------------------------------------------------

    // Provide AWS credentials for the REST call.
    CkAuthAwsW authAws;
    authAws.put_AccessKey(L"AWS_ACCESS_KEY");
    authAws.put_SecretKey(L"AWS_SECRET_KEY");
    authAws.put_ServiceName(L"s3");
    success = rest.SetAuthAws(authAws);

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

    int partNumber = 1;
    CkStringBuilderW sbPartNumber;

    while ((partNumber <= numParts)) {
        wprintf(L"---- %d ----\n",partNumber);

        // This cumbersome way of converting an integer to a string is because
        // Chilkat examples are written in a script that is converted to many programming languages.
        // At this time, the translator does not have integer-to-string code generation capability..
        sbPartNumber.Clear();
        sbPartNumber.AppendInt(partNumber);

        bool bPartAlreadyUploaded = false;

        // If there are no children, then the XML is empty and no parts have yet been uploaded.
        int numUploadedParts = partsListXml.get_NumChildren();
        if (numUploadedParts > 0) {
            // If some parts have been uploaded, check to see if this particular part was already upload.
            // If so, then it can be skipped.

            // Position ourselves at the 1st record.
            CkXmlW *xRec0 = partsListXml.GetChild(0);
            CkXmlW *foundRec = xRec0->FindNextRecord(L"PartNumber",sbPartNumber.getAsString());
            if (xRec0->get_LastMethodSuccess() == true) {
                bPartAlreadyUploaded = true;
                wprintf(L"Part %d was previously uploaded.\n",partNumber);
                wprintf(L"%s\n",foundRec->getXml());
                delete foundRec;
            }

            delete xRec0;
        }

        // If this part was not already uploaded, we need to upload.
        // Also update the partsListXml and save as each part is successfully uploaded.
        if (bPartAlreadyUploaded == false) {
            wprintf(L"Uploading part %d ...\n",partNumber);

            // Setup the stream source for the large file to be uploaded..
            CkStreamW fileStream;
            fileStream.put_SourceFile(fileToUploadPath);
            // The Chilkat Stream API has features to make uploading a parts
            // of a file easy.  Indicate the part size by setting the SourceFilePartSize
            // property.
            fileStream.put_SourceFilePartSize(partSize);

            // Our HTTP start line to upload a part will look like this:
            // PUT /ObjectName?partNumber=PartNumber&uploadId=UploadId HTTP/1.1

            // Set the query params.  We'll need partNumber and uploadId.
            // Make sure the query params from previous iterations are clear.
            rest.ClearAllQueryParams();
            rest.AddQueryParam(L"partNumber",sbPartNumber.getAsString());
            rest.AddQueryParam(L"uploadId",uploadId);

            // Upload this particular file part.
            // Tell the fileStream which part is being uploaded.
            // Our partNumber is 1-based (the 1st part is at index 1), but the fileStream's SourceFilePart
            // property is 0-based.  Therefore we use partNumber-1.
            fileStream.put_SourceFilePart(partNumber - 1);

            // Because the SourceFilePart and SourceFilePartSize properties are set, the stream will 
            // will provide just that part of the file.  
            const wchar_t *responseStr = rest.fullRequestStream(L"PUT",L"/somethingBig.zip",fileStream);
            if (rest.get_LastMethodSuccess() != true) {
                wprintf(L"%s\n",rest.lastErrorText());
                return;
            }

            if (rest.get_ResponseStatusCode() != 200) {
                // Examine the request/response to see what happened.
                wprintf(L"response status code = %d\n",rest.get_ResponseStatusCode());
                wprintf(L"response status text = %s\n",rest.responseStatusText());
                wprintf(L"response header: %s\n",rest.responseHeader());
                wprintf(L"response body: %s\n",responseStr);
                wprintf(L"---\n");
                wprintf(L"LastRequestStartLine: %s\n",rest.lastRequestStartLine());
                wprintf(L"LastRequestHeader: %s\n",rest.lastRequestHeader());
                return;
            }

            // OK, this part was uploaded..
            // The response will have a 0-length body.  The only information we need is the 
            // ETag response header field.
            const wchar_t *etag = rest.responseHdrByName(L"ETag");
            // It should be present, but just in case there was no ETag header...
            if (rest.get_LastMethodSuccess() != true) {
                wprintf(L"No ETag response header found!\n");
                wprintf(L"response header: %s\n",rest.responseHeader());
                return;
            }

            // We need to add record to the partsListXml.
            // The record will look like this:
            // &lt;Part>
            //   &lt;PartNumber>PartNumber&lt;/PartNumber>
            //   &lt;ETag>ETag&lt;/ETag>
            // &lt;/Part>
            CkXmlW *xPart = partsListXml.NewChild(L"Part",L"");
            xPart->NewChildInt2(L"PartNumber",partNumber);
            xPart->NewChild2(L"ETag",etag);
            delete xPart;

            success = partsListXml.SaveXml(partsListFile);
            if (success != true) {
                wprintf(L"%s\n",partsListXml.lastErrorText());
                return;
            }

            wprintf(L"-- Part %d uploaded. ---------------------\n",partNumber);
        }

        partNumber = partNumber + 1;
    }

    wprintf(L"Finished.  All parts uploaded.\n");
    }