(Lianja) 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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// 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.

loXmlInit = createobject("CkXml")
llSuccess = loXmlInit.LoadXmlFile("s3_multipart_uploads/initiate.xml")
if (llSuccess <> .T.) then
    ? "Did not find the initiate.xml XML file."
    release loXmlInit
    return
endif

lcUploadId = loXmlInit.GetChildContent("UploadId")
? "UploadId = " + lcUploadId

// 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
lcFileToUploadPath = "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.
lnPartSize = 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.
loFac = createobject("CkFileAccess")
loFac.OpenForRead(lcFileToUploadPath)

// How many parts will there be if each part is 5242880 bytes?
lnNumParts = loFac.GetNumBlocks(lnPartSize)
? "numParts = " + str(lnNumParts)
loFac.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..
lcPartsListFile = "s3_multipart_uploads/partsList.xml"
loPartsListXml = createobject("CkXml")
if (loFac.FileExists(lcPartsListFile) = .T.) then
    loPartsListXml.LoadXmlFile(lcPartsListFile)
endif

// Make sure the top-level tag is "CompleteMultipartUpload"
loPartsListXml.Tag = "CompleteMultipartUpload"

// --------------------------------------
// Before entering the loop to upload parts,
// setup the REST object with AWS authentication,
// and make the initial connection.
loRest = createobject("CkRest")

// Connect to the Amazon AWS REST server.
llBTls = .T.
lnPort = 443
llBAutoReconnect = .T.
llSuccess = loRest.Connect("s3.amazonaws.com",lnPort,llBTls,llBAutoReconnect)

// ----------------------------------------------------------------------------
// 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.
loAuthAws = createobject("CkAuthAws")
loAuthAws.AccessKey = "AWS_ACCESS_KEY"
loAuthAws.SecretKey = "AWS_SECRET_KEY"
loAuthAws.ServiceName = "s3"
llSuccess = loRest.SetAuthAws(loAuthAws)

// Set the bucket name via the HOST header.
// In this case, the bucket name is "chilkat100".
loRest.Host = "chilkat100.s3.amazonaws.com"
// --------------------------------------

lnPartNumber = 1
loSbPartNumber = createobject("CkStringBuilder")

do while (lnPartNumber <= lnNumParts)
    ? "---- " + str(lnPartNumber) + " ----"

    // 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..
    loSbPartNumber.Clear()
    loSbPartNumber.AppendInt(lnPartNumber)

    llBPartAlreadyUploaded = .F.

    // If there are no children, then the XML is empty and no parts have yet been uploaded.
    lnNumUploadedParts = loPartsListXml.NumChildren
    if (lnNumUploadedParts > 0) then
        // 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.
        loXRec0 = loPartsListXml.GetChild(0)
        loFoundRec = loXRec0.FindNextRecord("PartNumber",loSbPartNumber.GetAsString())
        if (loXRec0.LastMethodSuccess = .T.) then
            llBPartAlreadyUploaded = .T.
            ? "Part " + str(lnPartNumber) + " was previously uploaded."
            ? loFoundRec.GetXml()
            release loFoundRec
        endif

        release loXRec0
    endif

    // If this part was not already uploaded, we need to upload.
    // Also update the partsListXml and save as each part is successfully uploaded.
    if (llBPartAlreadyUploaded = .F.) then
        ? "Uploading part " + str(lnPartNumber) + " ..."

        // Setup the stream source for the large file to be uploaded..
        loFileStream = createobject("CkStream")
        loFileStream.SourceFile = lcFileToUploadPath
        // The Chilkat Stream API has features to make uploading a parts
        // of a file easy.  Indicate the part size by setting the SourceFilePartSize
        // property.
        loFileStream.SourceFilePartSize = lnPartSize

        // 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.
        loRest.ClearAllQueryParams()
        loRest.AddQueryParam("partNumber",loSbPartNumber.GetAsString())
        loRest.AddQueryParam("uploadId",lcUploadId)

        // 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.
        loFileStream.SourceFilePart = lnPartNumber - 1

        // Because the SourceFilePart and SourceFilePartSize properties are set, the stream will 
        // will provide just that part of the file.  
        lcResponseStr = loRest.FullRequestStream("PUT","/somethingBig.zip",loFileStream)
        if (loRest.LastMethodSuccess <> .T.) then
            ? loRest.LastErrorText
            release loXmlInit
            release loFac
            release loPartsListXml
            release loRest
            release loAuthAws
            release loSbPartNumber
            release loFileStream
            return
        endif

        if (loRest.ResponseStatusCode <> 200) then
            // Examine the request/response to see what happened.
            ? "response status code = " + str(loRest.ResponseStatusCode)
            ? "response status text = " + loRest.ResponseStatusText
            ? "response header: " + loRest.ResponseHeader
            ? "response body: " + lcResponseStr
            ? "---"
            ? "LastRequestStartLine: " + loRest.LastRequestStartLine
            ? "LastRequestHeader: " + loRest.LastRequestHeader
            release loXmlInit
            release loFac
            release loPartsListXml
            release loRest
            release loAuthAws
            release loSbPartNumber
            release loFileStream
            return
        endif

        // OK, this part was uploaded..
        // The response will have a 0-length body.  The only information we need is the 
        // ETag response header field.
        lcEtag = loRest.ResponseHdrByName("ETag")
        // It should be present, but just in case there was no ETag header...
        if (loRest.LastMethodSuccess <> .T.) then
            ? "No ETag response header found!"
            ? "response header: " + loRest.ResponseHeader
            release loXmlInit
            release loFac
            release loPartsListXml
            release loRest
            release loAuthAws
            release loSbPartNumber
            release loFileStream
            return
        endif

        // 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>
        loXPart = loPartsListXml.NewChild("Part","")
        loXPart.NewChildInt2("PartNumber",lnPartNumber)
        loXPart.NewChild2("ETag",lcEtag)
        release loXPart

        llSuccess = loPartsListXml.SaveXml(lcPartsListFile)
        if (llSuccess <> .T.) then
            ? loPartsListXml.LastErrorText
            release loXmlInit
            release loFac
            release loPartsListXml
            release loRest
            release loAuthAws
            release loSbPartNumber
            release loFileStream
            return
        endif

        ? "-- Part " + str(lnPartNumber) + " uploaded. ---------------------"
    endif

    lnPartNumber = lnPartNumber + 1
enddo

? "Finished.  All parts uploaded."


release loXmlInit
release loFac
release loPartsListXml
release loRest
release loAuthAws
release loSbPartNumber
release loFileStream