B4X

S3 Upload the Parts for a Multipart Upload

See more Amazon S3 (new) Examples

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.

B4X

Dim success As Boolean = False

'  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 ChilkatXml
xmlInit.Initialize
success = xmlInit.LoadXmlFile("s3_multipart_uploads/initiate.xml")
If success <> True Then
    Log("Did not find the initiate.xml XML file.")
    Return
End If


Dim uploadId As String = xmlInit.GetChildContent("UploadId")
Log("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 = "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 Int = 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 ChilkatFileAccess
fac.Initialize
fac.OpenForRead(fileToUploadPath)

'  How many parts will there be if each part is 5242880 bytes?
Dim numParts As Int = fac.GetNumBlocks(partSize)
Log("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 = "s3_multipart_uploads/partsList.xml"
Dim partsListXml As ChilkatXml
partsListXml.Initialize
If fac.FileExists(partsListFile) = True Then
    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 ChilkatRest
rest.Initialize("rest")

'  Connect to the Amazon AWS REST server.
Dim bTls As Boolean = True
Dim port As Int = 443
Dim bAutoReconnect As Boolean = 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 ChilkatAuthAws
authAws.Initialize
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 Int = 1
Dim sbPartNumber As ChilkatStringBuilder
sbPartNumber.Initialize

Do While (partNumber <= numParts)
    Log("---- " & 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)

    Dim bPartAlreadyUploaded As Boolean = False

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

        '  Setup the stream source for the large file to be uploaded..
        Dim fileStream As ChilkatStream
        fileStream.Initialize("fileStream")
        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.
        rest.ClearAllQueryParams
        rest.AddQueryParam("partNumber", sbPartNumber.GetAsString)
        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 = rest.FullRequestStream("PUT", "/somethingBig.zip", fileStream)
        If rest.LastMethodSuccess <> True Then
            Log(rest.LastErrorText)
            Return
        End If


        If rest.ResponseStatusCode <> 200 Then
            '  Examine the request/response to see what happened.
            Log("response status code = " & rest.ResponseStatusCode)
            Log("response status text = " & rest.ResponseStatusText)
            Log("response header: " & rest.ResponseHeader)
            Log("response body: " & responseStr)
            Log("---")
            Log("LastRequestStartLine: " & rest.LastRequestStartLine)
            Log("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 = rest.ResponseHdrByName("ETag")
        '  It should be present, but just in case there was no ETag header...
        If rest.LastMethodSuccess <> True Then
            Log("No ETag response header found!")
            Log("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 ChilkatXml = partsListXml.NewChild("Part", "")
        xPart.NewChildInt2("PartNumber", partNumber)
        xPart.NewChild2("ETag", etag)


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


        Log("-- Part " & partNumber & " uploaded. ---------------------")
    End If


    partNumber = partNumber + 1
Loop

Log("Finished.  All parts uploaded.")