(Visual Basic 6.0) Azure File Service: Upload Large File

Sample code to upload a large file to a directory in a share in the Azure File Service. A file is uploaded by first creating the file in the Azure share and then writing ranges of bytes to the file. Azure imposes a 4MB limit for each PUT to write a range. Files larger than 4MB need to be uploaded by making multiple "Put Range" calls. This example uploads a large file requiring multiple "Put Range" calls.

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' Azure File Service Example: Upload a large file.  
' See:  https://docs.microsoft.com/en-us/rest/api/storageservices/create-share
' also see: https://docs.microsoft.com/en-us/rest/api/storageservices/put-range

' 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.file.core.windows.net",port,bTls,bAutoReconnect)
If (success <> 1) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

' This example will upload a larger file.
Dim localFilePath As String
localFilePath = "qa_data/zips/somethingBig.zip"
Dim fac As New CkFileAccess
' Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
' the size of the file as a string, then convert to an integer value.
Dim szLocalFile As Long
szLocalFile = fac.FileSize(localFilePath)
If (szLocalFile < 0) Then
    Debug.Print fac.LastErrorText
    Exit Sub
End If

' Provide Azure Cloud credentials for the REST calls.
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 = "File"
' This causes the "x-ms-version: 2020-08-04" header to be automatically added.
azAuth.XMsVersion = "2020-08-04"
success = rest.SetAuthAzureStorage(azAuth)

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

' However, a few additional headers are required for the "Create File" operation:
success = rest.AddHeader("x-ms-type","file")

' This required header specifies the final size of the file (or the maximum size it can be).
Dim sbFileSize As New ChilkatStringBuilder
success = sbFileSize.AppendInt(szLocalFile)
success = rest.AddHeader("x-ms-content-length",sbFileSize.GetAsString())

' Send a PUT request to create the file (or replace the file if it already exists).
' This will initialize the file in the Azure file storage.  To upload content, we'll need
' to do the "Put Range" operation one or more times.

' The following will create the file "somethingBig.zip" in the share "pip"
Dim responseStr As String
responseStr = rest.FullRequestNoBody("PUT","/pip/somethingBig.zip")
If (rest.LastMethodSuccess <> 1) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

' When successful, the Azure File Service will respond with a 201 (Created) response status code,
' with no XML response body.  If an error response is returned, there will be an XML 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 "Successfully created somethingBig.zip"

' --------------------------------------------------------------------------------
' Upload the file data...

' Make sure the headers from the "Create File" operation are removed.
success = rest.ClearAllHeaders()

' The x-ms-write header is required for each "Put Range" request.
success = rest.AddHeader("x-ms-write","update")

Dim sbRange As New ChilkatStringBuilder
Dim sbResponseBody As New ChilkatStringBuilder
Dim bdFileData As New ChilkatBinData

' Open the file.  We'll be reading and uploading in chunks..
success = fac.OpenForRead(localFilePath)
If (success <> 1) Then
    Debug.Print fac.LastErrorText
    Exit Sub
End If

Dim numBytesLeft As Long
numBytesLeft = szLocalFile
Dim curIndex As Long
curIndex = 0
Do While numBytesLeft > 0

    Dim chunkSize As Long
    chunkSize = numBytesLeft
    ' Azure allows for 4MB max chunks  (4 x 1024 x 1024 = 4194304)
    If (chunkSize > 4194304) Then
        chunkSize = 4194304
    End If

    ' The only tricky part here is to correctly add the x-ms-range header.
    ' It will be formatted like this:
    ' x-ms-range: bytes=0-759623
    sbRange.Clear 
    success = sbRange.Append("bytes=")
    success = sbRange.AppendInt(curIndex)
    success = sbRange.Append("-")
    success = sbRange.AppendInt(curIndex + chunkSize - 1)

    ' This replaces the header if it already exists..
    success = rest.AddHeader("x-ms-range",sbRange.GetAsString())

    ' Read the next chunk from the local file.
    success = bdFileData.Clear()
    success = fac.FileReadBd(chunkSize,bdFileData)

    success = rest.FullRequestBd("PUT","/pip/somethingBig.zip?comp=range",bdFileData,sbResponseBody)
    If (success <> 1) Then
        ' This would indicate a failure where no response was received.
        Debug.Print rest.LastErrorText
        Exit Sub
    End If

    ' A 201 response indicates the chunk was uploaded.
    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 "Uploaded chunk from " & curIndex & " to " & (curIndex + chunkSize - 1)

    curIndex = curIndex + chunkSize
    numBytesLeft = numBytesLeft - chunkSize
Loop

fac.FileClose 

Debug.Print "success."