PowerBuilder

REST Asynchronous Streaming Upload Simplified

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This is example is simplified in that it calls FullRequestStreamAsync instead of making calls to SendReqStreamBodyAsync, ReadResponseHeader, and ReadRespBodyStr.

It demonstrates how to create and write to a stream that feeds an asynchronous upload 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.

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Rest
integer li_BTls
integer li_Port
integer li_BAutoReconnect
oleobject loo_AzAuth
oleobject loo_SendStream
oleobject loo_UploadTask
integer i
integer li_ResponseStatusCode
string ls_ResponseBodyStr

li_Success = 0

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

loo_Rest = create oleobject
li_rc = loo_Rest.ConnectToNewObject("Chilkat.Rest")
if li_rc < 0 then
    destroy loo_Rest
    MessageBox("Error","Connecting to COM object failed")
    return
end if

// Connect to the Azure Storage Blob Service
li_BTls = 1
li_Port = 443
li_BAutoReconnect = 1
// In this example, the storage account name is "chilkat".
li_Success = loo_Rest.Connect("chilkat.blob.core.windows.net",li_Port,li_BTls,li_BAutoReconnect)
if li_Success <> 1 then
    Write-Debug loo_Rest.LastErrorText
    destroy loo_Rest
    return
end if

// Provide Azure Cloud credentials for the REST call.
loo_AzAuth = create oleobject
li_rc = loo_AzAuth.ConnectToNewObject("Chilkat.AuthAzureStorage")

loo_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).
loo_AzAuth.Account = "chilkat"
loo_AzAuth.Scheme = "SharedKey"
loo_AzAuth.Service = "Blob"
// This causes the "x-ms-version: 2021-08-06" header to be automatically added.
loo_AzAuth.XMsVersion = "2021-08-06"
li_Success = loo_Rest.SetAuthAzureStorage(loo_AzAuth)

// Set some request headers.
li_Success = loo_Rest.AddHeader("x-ms-blob-content-disposition","attachment; filename=~"thisIsATest.txt~"")
li_Success = loo_Rest.AddHeader("x-ms-blob-type","BlockBlob")
li_Success = loo_Rest.AddHeader("x-ms-meta-m1","v1")
li_Success = loo_Rest.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.

loo_SendStream = create oleobject
li_rc = loo_SendStream.ConnectToNewObject("Chilkat.Stream")

// Create a background thread task to upload from the stream
// The name of the Azure storage container is "test".
// After the background task is started and running in a background thread,
// the foreground thread will write 100 text lines of "this is a test\r\n" to the
// stream.
loo_UploadTask = loo_Rest.FullRequestStreamAsync("PUT","/test/thisIsATest.txt",loo_SendStream)

// Start the task. 
li_Success = loo_UploadTask.Run()

// The application can write to the stream, and close the stream
// when finished.  Whatever is written to the stream uploaded to the remote file.

for i = 1 to 100
    li_Success = loo_SendStream.WriteString("This is a test~r~n")
    if li_Success <> 1 then
        li_Success = loo_UploadTask.Cancel()
        destroy loo_UploadTask
        Write-Debug "Failed to write to sendStream."
        destroy loo_Rest
        destroy loo_AzAuth
        destroy loo_SendStream
        return
    end if

next

// Close the stream to indicate no more data will be sent.
li_Success = loo_SendStream.WriteClose()

// Make sure the uploadTask has finished.
// It is likely that task is already finished..
// Wait a max of 5 seconds..
li_Success = loo_UploadTask.Wait(5000)

// FullRequestStreamAsync both sent the request and received the response.
// Check to see if the task finished properly.
if loo_UploadTask.StatusInt <> 7 then
    Write-Debug "Task did not end in the finished state."
    Write-Debug "Task status: " + loo_UploadTask.Status
    destroy loo_UploadTask
    destroy loo_Rest
    destroy loo_AzAuth
    destroy loo_SendStream
    return
end if

// Check to see if the call to FullRequestStream in the background thread pool succeeded.
if loo_UploadTask.TaskSuccess <> 1 then
    // Show what would've been the LastErrorText had FullRequestStream been called synchronously
    Write-Debug loo_UploadTask.ResultErrorText
    destroy loo_UploadTask
    destroy loo_Rest
    destroy loo_AzAuth
    destroy loo_SendStream
    return
end if

li_ResponseStatusCode = loo_Rest.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 li_ResponseStatusCode = 201 then
    Write-Debug "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.
    ls_ResponseBodyStr = loo_UploadTask.GetResultString()
    Write-Debug "response body (if any): " + ls_ResponseBodyStr

    // Examine the request/response to see what happened.
    Write-Debug "response status code = " + string(loo_Rest.ResponseStatusCode)
    Write-Debug "response status text = " + loo_Rest.ResponseStatusText
    Write-Debug "response header: " + loo_Rest.ResponseHeader
    Write-Debug "---"
    Write-Debug "LastRequestStartLine: " + loo_Rest.LastRequestStartLine
    Write-Debug "LastRequestHeader: " + loo_Rest.LastRequestHeader
end if



destroy loo_Rest
destroy loo_AzAuth
destroy loo_SendStream