Xbase++

REST Asynchronous Streaming Upload File

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Demonstrates how to asynchronous streaming upload a file to cloud storage. This particular example demonstrates an upload to the Azure Cloud Storage service. The same concepts apply to S3, Google Cloud, and Google Drive. Xbase++

LOCAL nSuccess
LOCAL oRest
LOCAL nBTls
LOCAL nPort
LOCAL nBAutoReconnect
LOCAL oAzAuth
LOCAL oSendStream
LOCAL oTask
LOCAL nCurPctDone
LOCAL nResponseStatusCode
LOCAL cResponseBodyStr

nSuccess := 0

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

oRest := CreateObject("Chilkat.Rest")

//  Connect to the Azure Storage Blob Service
nBTls := 1
nPort := 443
nBAutoReconnect := 1
//  In this example, the storage account name is "chilkat".
nSuccess := oRest:Connect("chilkat.blob.core.windows.net", nPort, nBTls, nBAutoReconnect)
IF (nSuccess != 1)
    ? oRest:LastErrorText
    oRest:destroy()
    RETURN
ENDIF

//  Provide Azure Cloud credentials for the REST call.
oAzAuth := CreateObject("Chilkat.AuthAzureStorage")
oAzAuth:AccessKey := "AZURE_ACCESS_KEY"
//  The account name used here should match the 1st part of the domain passed in the call to Connect (above).
oAzAuth:Account := "chilkat"
oAzAuth:Scheme := "SharedKey"
oAzAuth:Service := "Blob"
//  This causes the "x-ms-version: 2021-08-06" header to be automatically added.
oAzAuth:XMsVersion := "2021-08-06"
nSuccess := oRest:SetAuthAzureStorage(oAzAuth)

//  Set some request headers.
nSuccess := oRest:AddHeader("x-ms-blob-content-disposition", 'attachment; filename="thisIsATest.txt"')
nSuccess := oRest:AddHeader("x-ms-blob-type", "BlockBlob")
nSuccess := oRest:AddHeader("x-ms-meta-m1", "v1")
nSuccess := oRest:AddHeader("x-ms-meta-m2", "v2")

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

oSendStream := CreateObject("Chilkat.Stream")

//  Define the source data for the stream to be a file.
oSendStream:SourceFile := "qa_data/hamlet.xml"

//  Create a background thread task to upload from the stream
//  The name of the Azure storage container is "test".
oTask := oRest:FullRequestStreamAsync("PUT", "/test/thisIsATest.txt", oSendStream)

//  Start the task. 
nSuccess := oTask:Run()

//  In this example, we'll simply sleep and periodically
//  check to see if the REST upload if finished.
nCurPctDone := 0
DO WHILE oTask:Finished != 1
    oTask:SleepMs(100)
ENDDO

//  Check to see if the call to FullRequestStream in the background thread pool succeeded.
IF (oTask:TaskSuccess != 1)
    //  Show what would've been the LastErrorText had FullRequestStream been called synchronously
    ? oTask:ResultErrorText
    oTask:destroy()
    oRest:destroy()
    oAzAuth:destroy()
    oSendStream:destroy()
    RETURN
ENDIF

nResponseStatusCode := oRest:ResponseStatusCode

//  When successful, the Azure Storage service will respond with a 201 response code,
//  with an empty body.  Therefore, in the success condition, the responseStr is empty.
IF (nResponseStatusCode == 201)
    ? "File uploaded."
ELSE
    //  It failed, so examine the response body, if one was returned:
    //  Given that FullRequestStream returns a string, the return value is obtained via GetResultString.
    cResponseBodyStr := oTask:GetResultString()
    ? "response body (if any): " + cResponseBodyStr

    //  Examine the request/response to see what happened.
    ? "response status code = " + Str(oRest:ResponseStatusCode)
    ? "response status text = " + oRest:ResponseStatusText
    ? "response header: " + oRest:ResponseHeader
    ? "---"
    ? "LastRequestStartLine: " + oRest:LastRequestStartLine
    ? "LastRequestHeader: " + oRest:LastRequestHeader
ENDIF

oTask:destroy()

oRest:destroy()
oAzAuth:destroy()
oSendStream:destroy()