(Xojo Plugin) 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.

Dim xmlInit As New Chilkat.Xml
Dim success As Boolean
success = xmlInit.LoadXmlFile("s3_multipart_uploads/initiate.xml")
If (success <> True) Then
    System.DebugLog("Did not find the initiate.xml XML file.")
    Return
End If

Dim uploadId As String
uploadId = xmlInit.GetChildContent("UploadId")
System.DebugLog("UploadId = " + 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
Dim fileToUploadPath As String
fileToUploadPath = "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.
Dim partSize As Int32
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.
Dim fac As New Chilkat.FileAccess
success = fac.OpenForRead(fileToUploadPath)

// How many parts will there be if each part is 5242880 bytes?
Dim numParts As Int32
numParts = fac.GetNumBlocks(partSize)
System.DebugLog("numParts = " + Str(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..
Dim partsListFile As String
partsListFile = "s3_multipart_uploads/partsList.xml"
Dim partsListXml As New Chilkat.Xml
If (fac.FileExists(partsListFile) = True) Then
    success = partsListXml.LoadXmlFile(partsListFile)
End If

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

// --------------------------------------
// Before entering the loop to upload parts,
// setup the REST object with AWS authentication,
// and make the initial connection.
Dim rest As New Chilkat.Rest

// Connect to the Amazon AWS REST server.
Dim bTls As Boolean
bTls = True
Dim port As Int32
port = 443
Dim bAutoReconnect As Boolean
bAutoReconnect = True
success = rest.Connect("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.
Dim authAws As New Chilkat.AuthAws
authAws.AccessKey = "AWS_ACCESS_KEY"
authAws.SecretKey = "AWS_SECRET_KEY"
authAws.ServiceName = "s3"
success = rest.SetAuthAws(authAws)

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

Dim partNumber As Int32
partNumber = 1
Dim sbPartNumber As New Chilkat.StringBuilder

While (partNumber <= numParts)
    System.DebugLog("---- " + Str(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 
    success = sbPartNumber.AppendInt(partNumber)

    Dim bPartAlreadyUploaded As Boolean
    bPartAlreadyUploaded = False

    // If there are no children, then the XML is empty and no parts have yet been uploaded.
    Dim numUploadedParts As Int32
    numUploadedParts = partsListXml.NumChildren
    If (numUploadedParts > 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.
        Dim xRec0 As Chilkat.Xml
        xRec0 = partsListXml.GetChild(0)
        Dim foundRec As Chilkat.Xml
        foundRec = xRec0.FindNextRecord("PartNumber",sbPartNumber.GetAsString())
        If (xRec0.LastMethodSuccess = True) Then
            bPartAlreadyUploaded = True
            System.DebugLog("Part " + Str(partNumber) + " was previously uploaded.")
            System.DebugLog(foundRec.GetXml())

        End If

    End If

    // 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) Then
        System.DebugLog("Uploading part " + Str(partNumber) + " ...")

        // Setup the stream source for the large file to be uploaded..
        Dim fileStream As New Chilkat.Stream
        fileStream.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.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.
        success = rest.ClearAllQueryParams()
        success = rest.AddQueryParam("partNumber",sbPartNumber.GetAsString())
        success = rest.AddQueryParam("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.SourceFilePart = partNumber - 1

        // Because the SourceFilePart and SourceFilePartSize properties are set, the stream will 
        // will provide just that part of the file.  
        Dim responseStr As String
        responseStr = rest.FullRequestStream("PUT","/somethingBig.zip",fileStream)
        If (rest.LastMethodSuccess <> True) Then
            System.DebugLog(rest.LastErrorText)
            Return
        End If

        If (rest.ResponseStatusCode <> 200) Then
            // Examine the request/response to see what happened.
            System.DebugLog("response status code = " + Str(rest.ResponseStatusCode))
            System.DebugLog("response status text = " + rest.ResponseStatusText)
            System.DebugLog("response header: " + rest.ResponseHeader)
            System.DebugLog("response body: " + responseStr)
            System.DebugLog("---")
            System.DebugLog("LastRequestStartLine: " + rest.LastRequestStartLine)
            System.DebugLog("LastRequestHeader: " + rest.LastRequestHeader)
            Return
        End If

        // OK, this part was uploaded..
        // The response will have a 0-length body.  The only information we need is the 
        // ETag response header field.
        Dim etag As String
        etag = rest.ResponseHdrByName("ETag")
        // It should be present, but just in case there was no ETag header...
        If (rest.LastMethodSuccess <> True) Then
            System.DebugLog("No ETag response header found!")
            System.DebugLog("response header: " + rest.ResponseHeader)
            Return
        End If

        // 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>
        Dim xPart As Chilkat.Xml
        xPart = partsListXml.NewChild("Part","")
        xPart.NewChildInt2 "PartNumber",partNumber
        xPart.NewChild2 "ETag",etag

        success = partsListXml.SaveXml(partsListFile)
        If (success <> True) Then
            System.DebugLog(partsListXml.LastErrorText)
            Return
        End If

        System.DebugLog("-- Part " + Str(partNumber) + " uploaded. ---------------------")
    End If

    partNumber = partNumber + 1
Wend

System.DebugLog("Finished.  All parts uploaded.")