(Visual Basic 6.0) 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.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

' 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 ChilkatXml
Dim success As Long
success = xmlInit.LoadXmlFile("s3_multipart_uploads/initiate.xml")
If (success <> 1) Then
    Debug.Print "Did not find the initiate.xml XML file."
    Exit Sub
End If

Dim uploadId As String
uploadId = xmlInit.GetChildContent("UploadId")
Debug.Print "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 Long
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 CkFileAccess
success = fac.OpenForRead(fileToUploadPath)

' How many parts will there be if each part is 5242880 bytes?
Dim numParts As Long
numParts = fac.GetNumBlocks(partSize)
Debug.Print "numParts = " & 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 ChilkatXml
If (fac.FileExists(partsListFile) = 1) 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 ChilkatRest

' Connect to the Amazon AWS REST server.
Dim bTls As Long
bTls = 1
Dim port As Long
port = 443
Dim bAutoReconnect As Long
bAutoReconnect = 1
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 ChilkatAuthAws
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 Long
partNumber = 1
Dim sbPartNumber As New ChilkatStringBuilder

Do While (partNumber <= numParts)
    Debug.Print "---- " & 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 Long
    bPartAlreadyUploaded = 0

    ' If there are no children, then the XML is empty and no parts have yet been uploaded.
    Dim numUploadedParts As Long
    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 ChilkatXml
        Set xRec0 = partsListXml.GetChild(0)
        Dim foundRec As ChilkatXml
        Set foundRec = xRec0.FindNextRecord("PartNumber",sbPartNumber.GetAsString())
        If (xRec0.LastMethodSuccess = 1) Then
            bPartAlreadyUploaded = 1
            Debug.Print "Part " & partNumber & " was previously uploaded."
            Debug.Print 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 = 0) Then
        Debug.Print "Uploading part " & partNumber & " ..."

        ' Setup the stream source for the large file to be uploaded..
        Dim fileStream As New ChilkatStream
        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 <> 1) Then
            Debug.Print rest.LastErrorText
            Exit Sub
        End If

        If (rest.ResponseStatusCode <> 200) Then
            ' Examine the request/response to see what happened.
            Debug.Print "response status code = " & rest.ResponseStatusCode
            Debug.Print "response status text = " & rest.ResponseStatusText
            Debug.Print "response header: " & rest.ResponseHeader
            Debug.Print "response body: " & responseStr
            Debug.Print "---"
            Debug.Print "LastRequestStartLine: " & rest.LastRequestStartLine
            Debug.Print "LastRequestHeader: " & rest.LastRequestHeader
            Exit Sub
        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 <> 1) Then
            Debug.Print "No ETag response header found!"
            Debug.Print "response header: " & rest.ResponseHeader
            Exit Sub
        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 ChilkatXml
        Set xPart = partsListXml.NewChild("Part","")
        xPart.NewChildInt2 "PartNumber",partNumber
        xPart.NewChild2 "ETag",etag

        success = partsListXml.SaveXml(partsListFile)
        If (success <> 1) Then
            Debug.Print partsListXml.LastErrorText
            Exit Sub
        End If

        Debug.Print "-- Part " & partNumber & " uploaded. ---------------------"
    End If

    partNumber = partNumber + 1
Loop

Debug.Print "Finished.  All parts uploaded."