(Visual Basic 6.0) Upload File in Blocks and Commit the Block List

See more Azure Cloud Storage Examples

Demonstrates how to upload a file in blocks and then commit the block list. For files larger than 64MB, this is the way to upload to Azure Storage. Azure limits the size of each block to a maximum of 4MB.

For more information, see https://learn.microsoft.com/en-us/rest/api/storageservices/put-block-list?tabs=microsoft-entra-id

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

' Azure Blob Service Example: Upload a file in blocks, and then commit the block list.
' See also: https://msdn.microsoft.com/en-us/library/azure/dd135726.aspx

' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim rest As New ChilkatRest

' Connect to the Azure Storage Blob Service
Dim bTls As Long
bTls = 1
Dim port As Long
port = 443
Dim bAutoReconnect As Long
bAutoReconnect = 1
' In this example, the storage account name is "chilkat".
Dim success As Long
success = rest.Connect("chilkat.blob.core.windows.net",port,bTls,bAutoReconnect)
If (success <> 1) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

' Provide Azure Cloud credentials for the REST call.
Dim azAuth As New ChilkatAuthAzureStorage
azAuth.AccessKey = "AZURE_ACCESS_KEY"
' The account name used here should match the 1st part of the domain passed in the call to Connect (above).
azAuth.Account = "chilkat"
azAuth.Scheme = "SharedKey"
azAuth.Service = "Blob"
' This causes the "x-ms-version: 2021-08-06" header to be automatically added.
azAuth.XMsVersion = "2021-08-06"
success = rest.SetAuthAzureStorage(azAuth)

' Note: The application does not need to explicitly set the following
' headers: Content-Length, x-ms-date, Authorization.  These headers
' are automatically set by Chilkat.

' As the blocks are uploaded, we'll keep an XML block list for the subsequent commit..
Dim xml As New ChilkatXml
xml.Tag = "BlockList"

' Any type of file can be uploaded in this way.  It can a text file, binary file, anything...
' This example will upload an XML file that is approximately 275K in size.  It can be downloaded
' at http://www.chilkatsoft.com/hamlet.xml
Dim fac As New CkFileAccess
success = fac.OpenForRead("qa_data/xml/hamlet.xml")
' Assuming success for the example..

' We'll upload in 16K blocks (normally a program would upload in larger block sizes than this,
' but this is just an example...)
Dim blockSize As Long
blockSize = 16384

' How many 16K blocks?  (Including 1 for the last partial block)
Dim numBlocks As Long
numBlocks = fac.GetNumBlocks(blockSize)

Dim sbResponseBody As New ChilkatStringBuilder
Dim uriPath As New ChilkatStringBuilder
Dim blockId As String
Dim dataBlock As New ChilkatBinData
Dim i As Long
i = 0
Do While i < numBlocks

    success = dataBlock.Clear()
    success = fac.ReadBlockBd(i,blockSize,dataBlock)
    If (success = 0) Then
        Debug.Print fac.LastErrorText
        Exit Sub
    End If

    ' Generate a base64 block ID.  
    ' (Chilkat provides a helper method named GenBlockId to make this easy)
    ' A pre-base64 encoded block ID length of 4 is sufficient in this case because
    ' this file certainly won't have more than 99,999 blocks..
    blockId = fac.GenBlockId(i,4,"base64")

    ' Add this blockId to the list of blocks to be committed.
    xml.NewChild2 "Latest",blockId

    ' Build the URI path
    uriPath.Clear 
    success = uriPath.Append("/mycontainer/hamlet.xml?comp=block&blockId=")
    success = uriPath.Append(blockId)

    ' Upload this block..
    sbResponseBody.Clear 
    success = rest.FullRequestBd("PUT",uriPath.GetAsString(),dataBlock,sbResponseBody)
    If (success = 0) Then
        Debug.Print rest.LastErrorText
        Exit Sub
    End If

    ' Verify that we received a 201 status code.
    If (rest.ResponseStatusCode <> 201) 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 (if any): " & sbResponseBody.GetAsString()
        Debug.Print "---"
        Debug.Print "LastRequestStartLine: " & rest.LastRequestStartLine
        Debug.Print "LastRequestHeader: " & rest.LastRequestHeader
        Exit Sub
    End If

    i = i + 1
Loop

fac.FileClose 

' Now commit the blocks.
' Let's have a look at the XML that will commit the blocks:
Dim xmlStr As String
xmlStr = xml.GetXml()
Debug.Print xmlStr

' The XML will look like this:

' <?xml version="1.0" encoding="utf-8" ?>
' <BlockList>
'     <Latest>MDAwMA==</Latest>
'     <Latest>MDAwMQ==</Latest>
'     <Latest>MDAwMg==</Latest>
'     <Latest>MDAwMw==</Latest>
'     <Latest>MDAwNA==</Latest>
'     <Latest>MDAwNQ==</Latest>
'     <Latest>MDAwNg==</Latest>
'     <Latest>MDAwNw==</Latest>
'     <Latest>MDAwOA==</Latest>
'     <Latest>MDAwOQ==</Latest>
'     <Latest>MDAxMA==</Latest>
'     <Latest>MDAxMQ==</Latest>
'     <Latest>MDAxMg==</Latest>
'     <Latest>MDAxMw==</Latest>
'     <Latest>MDAxNA==</Latest>
'     <Latest>MDAxNQ==</Latest>
'     <Latest>MDAxNg==</Latest>
'     <Latest>MDAxNw==</Latest>
' </BlockList>

' Send the PUT Block List...
Dim responseStr As String
responseStr = rest.FullRequestString("PUT","/mycontainer/hamlet.xml?comp=blocklist",xmlStr)
If (rest.LastMethodSuccess <> 1) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

' When successful, the Azure Storage service will respond with a 201 response status code,
' with no response body.

If (rest.ResponseStatusCode <> 201) 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 (if any): " & responseStr
    Debug.Print "---"
    Debug.Print "LastRequestStartLine: " & rest.LastRequestStartLine
    Debug.Print "LastRequestHeader: " & rest.LastRequestHeader
    Exit Sub
End If

Debug.Print "Success."