Question

As a followup to the previous question I have asked “ASP.Net Architecture Specific to Shared/Static functions”

I am still struggling to understand the implications of using shared methods in ASP.NET.

So for example let us take the following code.

    Public Shared Function GetCategoryByID(ByVal CategoryID As Guid) As Category
        If Not CategoryID.Equals(Guid.Empty) Then
            Dim res As New Category

            Using sqlConn As New SqlConnection(My.Settings.ConnectionString)
                sqlConn.Open()

                Using dr As IDataReader = CategoryDataLayer.GetCategoryByIDQuery(sqlConn, CategoryID)
                    Return CType(BaseDataLayer.FillObject(res, dr), Category)
                End Using
            End Using

        Else
            Return Nothing
        End If
    End Function

Now I imagine client 1 connecting and running this method GetCategoryByID() from their session with the guid {A20E625F-2333-4742-BFD9-05BE7649222D}.

Let us now say that for example the process is about to execute the following line.

Using dr As IDataReader = CategoryDataLayer.GetCategoryByIDQuery(sqlConn, CategoryID)

At this point client 2 runs the same shared method but with the guid {6D806B82-FC7F-4124-AFB9-45E2689BC9F5}.

Does CategoryID not at this point become {6D806B82-FC7F-4124-AFB9-45E2689BC9F5} and therefor interfere with client 1 because now CategoryID has changed given that this is a shared method?

Could someone please clarify?

PS: I do apologize for what is essentially a duplicate post but in retrospect I don’t feel the answer in the original post was clear enough (at least for me). Perhaps I wasn’t specific enough either…

Answer 1

In your code sample, the variable res is a local variable of the shared method. No one, not even another shared method can touch that variable. It will exist for the lifetime of the method and then its gone. CategoryId is the exact same, its a local variable that cannot be touched from outside.

VB has another concept called Static which is very different than the C# version of static which can cause some confusion.