webservice gurus, help with asynchronous invoking

[Glowworm27]

Hey group,

I have a question relating to calling a Webservice method asynchronously.

The question is this; I have a webmethod() that will download a file and import the file into the database. I have a webpage that allows the user to tell it the filename, and then click on the button, to invoke the webservice to download and import the file.
I want to invoke the webservice asynchronously so the user does not need to wait around for the import to finish. I want to the user to be able to go to other pages, and continue working on other stuff. I dont care if the user ever gets notified that the import was completed, I will write a line to the status of the application that all can see from the front page.
Is this do-able or must the user stay on that page until the webservice completes?

Thanks in Advance


George Oakes
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[bassguy]

hi,
i am at work and my reference is at home. but I would suggest the visual basic programmers cookbook. it has webservice code in it.

i will post more tonight when I find it.

bassguy

 

[NipsMG]

What I would to for this, is in the webservice class, create the following:

Public Delegate Sub Status_Message(ByVal Message as String)
Private m_smStatus as Status_Message

Make the constructor in the webservice class like this:

Public Sub New(ByVal StatusCallback as Status_Message)
    m_smStatus = StatusCallback
End Sub

IN the webservice class, you'll need the following

Public Property FileToUpload() As String
        Get
            Return m_strFileName
        End Get
        Set(ByVal Value As String)
            m_StrFileName = Value
        End Set
End Property

and some subroute to fire off the uploading.

Public Sub UploadFile()
    'Do uploading here
Exit Sub

In the UI, you have to create a Sub that will handle the status message callbacks:

Public Sub StatusMessageFired(ByVal Message as String)
   MyStatusLabel.Text = Message
End Sub

In the button click event:

Public Sub Button_Click(blahblah) Handles Button.Click
   Dim ws as new MyWebService(AddressOf StatusMessageFired)

   ws.FileNameToUpload = strFileName

   Dim threadWeb as New _
      System.Threading.Thread(ws.UploadFile())
   threadWeb.Start
End Sub

Something like that should work.

--NipsMG

 

[NipsMG]

Oh yeah, and in the webservice, you can fire a status message back to the client by:

    m_smStatus.Invoke("My Status Message")