Question

I want to be able to save variables between calls to my WCF service for various reasons. I have the following, which works, but I read that using “Single” is a really bad idea. This is really a prototype and nothing critical, but it does have multiple users and I’m afraid single will mean it sets the same variables across all user sessions. Can someone confirm/deny this? It doesn’t work at all when I set it to PerSession, which is logically what I would think I would want.

<ServiceContract(Namespace:="")> _
<AspNetCompatibilityRequirements(RequirementsMode:=AspNetCompatibilityRequirementsMode.Allowed)> _
<ServiceBehavior(InstanceContextMode:=ServiceModel.InstanceContextMode.Single, ConcurrencyMode:=ServiceModel.ConcurrencyMode.Single)> _
Public Class MyServices
    Public testint As Integer = 0

    <WebGet()>
    <OperationContract()> _
    Public Function test1() As Boolean
        testint = 42
        return true
    End Function

    <WebGet()>
    <OperationContract()> _
    Public Function test2() As Integer
        return testint
    End Function
End Class

I read something about a “Durable” service, but VS2010 only lets me choose PerCall, PerSession and Single for the InstanceContextMode.

Answer 1

Check out the WCF Documentation about Session handling (MSDN)
If you´re working on a prototype you can get along building a static dictionary, in which you can dump your values in combination with a session key