Preserve objects between wcf calls?

This should be fairly basic, but say I have a Public property as local variable on my WCF service, and I set this in one call to the service. Is the开发者_运维知识库re a way to preserve that data for another call to the service? (Without writing the data to xml or a db, and re-referencing it or anything like that)

Executing the calls from the Winform:

Public Class ClientSideWinForm

    Private proxy As ServiceReference.Client

    Private Sub Client_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        proxy = New ServiceReference.Client
    End Sub

    Private Sub btnStartTests_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStartTests.Click
        addToTxtResults("Try Chk Program Valid...")
        Try
            addToTxtResults(proxy.RequestChkValidProgram("Some-serial-number")) 'returns true or false and instanciates the object server side

            addToTxtResults(proxy.RequestFirstName()) ' returns nothing
        Catch ex As Exception
            addToTxtResults(ex.ToString)
        End Try
    End Sub
End Class

The service itself (dumbed down a bit, but the behaivor still exists):

Public Class Service
    Implements IService

Public Property X As String

Function RequestChkValidProgram(ByVal strSerialNumber As String) As Integer Implements IService.RequestChkValidProgram
        X = "hello"
End Function

Function RequestFirstName() As String Implements IService.RequestFirstName
    Return X
End Function

End Class

If I understand the question correctly, your service implementation's state is lost between service calls. You should look into setting the InstanceContextMode ServiceBehavior of your service implementation - it sounds like it's currently set to PerCall, such that every service call gets its own instance. PerSession or Single may be better alternatives.

And while I don't necessarily agree with @John Saunders that this is a bad idea, it would be useful to have more details about what you're trying to accomplish. :)

If you only have a single instance of your service, then you can preserve data from one call to the next. You should consider telling us why you want to do this, as it sounds like a bad idea.