B4X

Azure Storage: CORS Preflight Blob Request

See more Azure Cloud Storage Examples

Azure Storage Blob Service REST API: Sample code to send a CORS pre-flight blob request. B4X

Dim success As Boolean = False

'  Azure Blob Service Example: CORS Preflight Blob Request
'  See also: https://msdn.microsoft.com/en-us/library/azure/dn535599.aspx

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

Dim rest As ChilkatRest
rest.Initialize("rest")

'  Connect to the Azure Storage Blob Service
Dim bTls As Boolean = True
Dim port As Int = 443
Dim bAutoReconnect As Boolean = True
'  In this example, the storage account name is "chilkat".
success = rest.Connect("chilkat.blob.core.windows.net", port, bTls, bAutoReconnect)
If success <> True Then
    Log(rest.LastErrorText)
    Return
End If


'  Provide Azure Cloud credentials for the REST call.
Dim azAuth As ChilkatAuthAzureStorage
azAuth.Initialize
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 = "Blob"
'  This causes the "x-ms-version: 2021-08-06" header to be automatically added.
azAuth.XMsVersion = "2021-08-06"
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.

'  The preflight blob request requires the following two HTTP headers.
'  The Origin is the domain from which the actual request will be issued.
success = rest.AddHeader("Origin", "www.contoso.com")
'  The Access-Control-Request-Method is the HTTP method (such as GET, POST, PUT, etc.) of the actual request.
success = rest.AddHeader("Access-Control-Request-Method", "PUT")

'  The expected response is a 202 response status code with no response body.
'  The name of the container or blob resource in this example is "test". (Replace "test" with your container name.)
Dim responseStr As String = rest.FullRequestNoBody("OPTIONS", "/test")
If rest.LastMethodSuccess <> True Then
    Log(rest.LastErrorText)
    Return
End If


'  When successful, the Azure Storage service will respond with a 200 response code,
'  with no response body.

'  If CORS is not enabled or no matching rule is found for the request, 
'  then a 403 status code is returned, with the following status text:
'  "CORS not enabled or no matching rule found for this request."
If rest.ResponseStatusCode <> 200 Then
    '  Examine the request/response to see what happened.
    Log("response status code = " & rest.ResponseStatusCode)
    Log("response status text = " & rest.ResponseStatusText)
    Log("response header: " & rest.ResponseHeader)
    Log("response body (if any): " & responseStr)
    Log("---")
    Log("LastRequestStartLine: " & rest.LastRequestStartLine)
    Log("LastRequestHeader: " & rest.LastRequestHeader)
    Return
End If


Log("Success: Preflight Blob Request is accepted.")