ASP Implementation
The native ASP session can only store session data in memory. In order to store the session data to SQL Server, a custom Microsoft® Visual Basic® 6.0 COM object is written to manage the session state instead of using the native session object. This COM object will be instantiated in the beginning of each Web request and reload the session data from SQL Server. When the ASP script is finished, this object will be terminated and the session state will be persisted back to SQL Server.

The primary purpose of the Visual Basic 6 COM Session object is to provide access to the Microsoft® Internet Information Server intrinsic objects. The Visual Basic 6.0 COM Session object uses the mySession class of SessionUtility assembly to hold the session state, and the SessionPersistence class of SessionUtility to load and save session data with SQL Server. The mySession and SessionPersistence classes are exposed as COM objects using the regasm.exe utility. The regasm.exe utility can register and create a type library for the COM client to consume Framework classes.

The session state information is reloaded during the construction of the object. The constructor (class_initialize) will first retrieve the session cookie, session timeout (SessionTimeOut), and database connection string (SessionDSN) from the Application object, and create an instance of the class mySession to hold the session data. Then the constructor will try to reload the session data from SQL Server with the given cookie. If the SQL Server does not have the session information, or the session has been expired, a new cookie will be issued. If the SQL Sever does return with the session state data, the session state will be stored in the mySession object.

Private Sub Class_Initialize()
On Error GoTo ErrHandler:
    Const METHOD_NAME As String = "Class_Initialize"
    Set mySessionPersistence = New SessionPersistence
    Set myObjectContext = GetObjectContext()
    mySessionID = ReadSessionID()
    myDSNString = GetConnectionDSN()
    myTimeOut = GetSessionTimeOut()
    myIsNewSession = False
    Call InitContents
    
    Exit Sub
ErrHandler:
    Err.Raise Err.Number, METHOD_NAME & ":" & Err.Source, Err.Description
End Sub

Private Sub InitContents()
On Error GoTo ErrHandler:
    Const METHOD_NAME As String = "InitContents"    
    If mySessionID = "" Then
        Set myContentsEntity = New mySession
        mySessionID = mySessionPersistence.GenerateKey
        myIsNewSession = True
    Else
        Set myContentsEntity =
        mySessionPersistence.LoadSession(mySessionID, myDSNString, myTimeOut)
    End If
        
    Exit Sub
ErrHandler:
    Err.Raise Err.Number, METHOD_NAME & ":" & Err.Source, Err.Description
End Sub

When the object instance goes out of scope in the script, the destructor (class_terminate) will execute. The destructor will persist the session data using the SessionPersistence.SaveSession() method. If this is a new session, the destructor will also send the new cookie back to the browser.

Private Sub Class_Terminate()
On Error GoTo ErrHandler:
    Const METHOD_NAME As String = "Cl