(Lianja) 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.

loRest = createobject("CkRest")

// Connect to the Azure Storage Blob Service
llBTls = .T.
lnPort = 443
llBAutoReconnect = .T.
// In this example, the storage account name is "chilkat".
llSuccess = loRest.Connect("chilkat.file.core.windows.net",lnPort,llBTls,llBAutoReconnect)
if (llSuccess <> .T.) then
    ? loRest.LastErrorText
    release loRest
    return
endif

// This example will upload a larger file.
lcLocalFilePath = "qa_data/zips/somethingBig.zip"
loFac = createobject("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.
lnSzLocalFile = loFac.FileSize(lcLocalFilePath)
if (lnSzLocalFile < 0) then
    ? loFac.LastErrorText
    release loRest
    release loFac
    return
endif

// Provide Azure Cloud credentials for the REST calls.
loAzAuth = createobject("CkAuthAzureStorage")
loAzAuth.AccessKey = "AZURE_ACCESS_KEY"
// The account name used here should match the 1st part of the domain passed in the call to Connect (above).
loAzAuth.Account = "chilkat"
loAzAuth.Scheme = "SharedKey"
loAzAuth.Service = "File"
// This causes the "x-ms-version: 2020-08-04" header to be automatically added.
loAzAuth.XMsVersion = "2020-08-04"
llSuccess = loRest.SetAuthAzureStorage(loAzAuth)

// 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:
loRest.AddHeader("x-ms-type","file")

// This required header specifies the final size of the file (or the maximum size it can be).
loSbFileSize = createobject("CkStringBuilder")
loSbFileSize.AppendInt(lnSzLocalFile)
loRest.AddHeader("x-ms-content-length",loSbFileSize.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"
lcResponseStr = loRest.FullRequestNoBody("PUT","/pip/somethingBig.zip")
if (loRest.LastMethodSuccess <> .T.) then
    ? loRest.LastErrorText
    release loRest
    release loFac
    release loAzAuth
    release loSbFileSize
    return
endif

// 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 (loRest.ResponseStatusCode <> 201) then
    // Examine the request/response to see what happened.
    ? "response status code = " + str(loRest.ResponseStatusCode)
    ? "response status text = " + loRest.ResponseStatusText
    ? "response header: " + loRest.ResponseHeader
    ? "response body (if any): " + lcResponseStr
    ? "---"
    ? "LastRequestStartLine: " + loRest.LastRequestStartLine
    ? "LastRequestHeader: " + loRest.LastRequestHeader
    release loRest
    release loFac
    release loAzAuth
    release loSbFileSize
    return
endif

? "Successfully created somethingBig.zip"

// --------------------------------------------------------------------------------
// Upload the file data...

// Make sure the headers from the "Create File" operation are removed.
loRest.ClearAllHeaders()

// The x-ms-write header is required for each "Put Range" request.
loRest.AddHeader("x-ms-write","update")

loSbRange = createobject("CkStringBuilder")
loSbResponseBody = createobject("CkStringBuilder")
loBdFileData = createobject("CkBinData")

// Open the file.  We'll be reading and uploading in chunks..
llSuccess = loFac.OpenForRead(lcLocalFilePath)
if (llSuccess <> .T.) then
    ? loFac.LastErrorText
    release loRest
    release loFac
    release loAzAuth
    release loSbFileSize
    release loSbRange
    release loSbResponseBody
    release loBdFileData
    return
endif

lnNumBytesLeft = lnSzLocalFile
lnCurIndex = 0
do while lnNumBytesLeft > 0

    lnChunkSize = lnNumBytesLeft
    // Azure allows for 4MB max chunks  (4 x 1024 x 1024 = 4194304)
    if (lnChunkSize > 4194304) then
        lnChunkSize = 4194304
    endif

    // 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
    loSbRange.Clear()
    loSbRange.Append("bytes=")
    loSbRange.AppendInt(lnCurIndex)
    loSbRange.Append("-")
    loSbRange.AppendInt(lnCurIndex + lnChunkSize - 1)

    // This replaces the header if it already exists..
    loRest.AddHeader("x-ms-range",loSbRange.GetAsString())

    // Read the next chunk from the local file.
    loBdFileData.Clear()
    llSuccess = loFac.FileReadBd(lnChunkSize,loBdFileData)

    llSuccess = loRest.FullRequestBd("PUT","/pip/somethingBig.zip?comp=range",loBdFileData,loSbResponseBody)
    if (llSuccess <> .T.) then
        // This would indicate a failure where no response was received.
        ? loRest.LastErrorText
        release loRest
        release loFac
        release loAzAuth
        release loSbFileSize
        release loSbRange
        release loSbResponseBody
        release loBdFileData
        return
    endif

    // A 201 response indicates the chunk was uploaded.
    if (loRest.ResponseStatusCode <> 201) then
        // Examine the request/response to see what happened.
        ? "response status code = " + str(loRest.ResponseStatusCode)
        ? "response status text = " + loRest.ResponseStatusText
        ? "response header: " + loRest.ResponseHeader
        ? "response body (if any): " + lcResponseStr
        ? "---"
        ? "LastRequestStartLine: " + loRest.LastRequestStartLine
        ? "LastRequestHeader: " + loRest.LastRequestHeader
        release loRest
        release loFac
        release loAzAuth
        release loSbFileSize
        release loSbRange
        release loSbResponseBody
        release loBdFileData
        return
    endif

    ? "Uploaded chunk from " + str(lnCurIndex) + " to " + str(lnCurIndex + lnChunkSize - 1)

    lnCurIndex = lnCurIndex + lnChunkSize
    lnNumBytesLeft = lnNumBytesLeft - lnChunkSize
enddo

loFac.FileClose()

? "success."


release loRest
release loFac
release loAzAuth
release loSbFileSize
release loSbRange
release loSbResponseBody
release loBdFileData