Visual FoxPro

Azure File Service: Upload Large File

See more Azure Cloud Storage Examples

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. Visual FoxPro

LOCAL lnSuccess
LOCAL loRest
LOCAL lnBTls
LOCAL lnPort
LOCAL lnBAutoReconnect
LOCAL lcLocalFilePath
LOCAL loFac
LOCAL lnSzLocalFile
LOCAL loAzAuth
LOCAL loSbFileSize
LOCAL lcResponseStr
LOCAL loSbRange
LOCAL loSbResponseBody
LOCAL loBdFileData
LOCAL lnNumBytesLeft
LOCAL lnCurIndex
LOCAL lnChunkSize

lnSuccess = 0

* 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('Chilkat.Rest')

* Connect to the Azure Storage Blob Service
lnBTls = 1
lnPort = 443
lnBAutoReconnect = 1
* In this example, the storage account name is "chilkat".
lnSuccess = loRest.Connect("chilkat.file.core.windows.net",lnPort,lnBTls,lnBAutoReconnect)
IF (lnSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    CANCEL
ENDIF

* This example will upload a larger file.
lcLocalFilePath = "qa_data/zips/somethingBig.zip"
loFac = CreateObject('Chilkat.FileAccess')
* 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
    CANCEL
ENDIF

* Provide Azure Cloud credentials for the REST calls.
loAzAuth = CreateObject('Chilkat.AuthAzureStorage')
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: 2021-08-06" header to be automatically added.
loAzAuth.XMsVersion = "2021-08-06"
lnSuccess = 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('Chilkat.StringBuilder')
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 <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    RELEASE loFac
    RELEASE loAzAuth
    RELEASE loSbFileSize
    CANCEL
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
    CANCEL
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('Chilkat.StringBuilder')
loSbResponseBody = CreateObject('Chilkat.StringBuilder')
loBdFileData = CreateObject('Chilkat.BinData')

* Open the file.  We'll be reading and uploading in chunks..
lnSuccess = loFac.OpenForRead(lcLocalFilePath)
IF (lnSuccess <> 1) THEN
    ? loFac.LastErrorText
    RELEASE loRest
    RELEASE loFac
    RELEASE loAzAuth
    RELEASE loSbFileSize
    RELEASE loSbRange
    RELEASE loSbResponseBody
    RELEASE loBdFileData
    CANCEL
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()
    lnSuccess = loFac.FileReadBd(lnChunkSize,loBdFileData)

    lnSuccess = loRest.FullRequestBd("PUT","/pip/somethingBig.zip?comp=range",loBdFileData,loSbResponseBody)
    IF (lnSuccess <> 1) 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
        CANCEL
    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
        CANCEL
    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