Field	Type	Notes	Description
SID	char (32)	Primary Key	The Session ID
DATA	Text		The actual session data
LASTCHANGE	DateTime		Date and time of last access to the data

Figure 2   CGUIDGenerator

 STDMETHODIMP CGUIDGenerator::get_GetGUID(BSTR *pVal)
 {
     AFX_MANAGE_STATE(AfxGetStaticModuleState())
 
     // This function creates a GUID and returns it as a string
 
     GUID    gGuid;
     CString    sGuid;
 
     CoCreateGuid (&gGuid);
     
     sGuid.Format ("%X%X%X%X%X%X%X%X%X%X%X", 
                   gGuid.Data1, 
                   gGuid.Data2, 
                   gGuid.Data3, 
                   gGuid.Data4[0],
                   gGuid.Data4[1],
                   gGuid.Data4[2],
                   gGuid.Data4[3],
                   gGuid.Data4[4],
                   gGuid.Data4[5],
                   gGuid.Data4[6],
                   gGuid.Data4[7]);
 
     *pVal = sGuid.AllocSysString();
 
     return S_OK;
 }

Figure 3   Sample System Objects

Object	Description
SessionElement	The individual element of a session. It exposes two properties: its name and its value.
ElementCollection	A collection of SessionElement objects that represents the individual user session. New elements can be added to it, and existing ones can be retrieved or deleted.
SessionObject	Fundamentally, a collection of Element- Collection objects. It represents a cache of all the sessions available on the current server. In addition, it can be used to retrieve and save sessions to the database.
Session	A wrapper component that is returned by SessionObject whenever the ASP script requests a session. It provides pass- through access to the appropriate instance of ElementCollection, plus the functionality needed to synchronize the data when changes take place during the script's execution.

Figure 4   The System's Stored Procedures

 Create Procedure CreateRetrieveSession
     (
         @SessionID char (32)
     )
 As
     set nocount on
     
     if exists (select SID from SESSIONS where SID = @SessionID)
         begin
         
             /* if record is already in database, update last modified datetime */
         
             update SESSIONS set LASTCHANGE = GETDATE() where SID = @SessionID
         
         end
         
     else
     
         begin
         
             /* Create a new record for this session ID */
             
             insert SESSIONS (SID, DATA) values (@SessionID, NULL)
             
         end
     
         /* Now, return result to caller */
         
         select DATA, LASTCHANGE from SESSIONS where SID = @SessionID
         
     return 
 
 Create Procedure GetLastModifiedDate
     (
         @SessionID char (32)
     )
 As
     select LASTCHANGE from SESSIONS where SID = @SessionID
 
 Create Procedure PurgeOldSessions
 As
     set nocount on
     
     select SID from SESSIONS where DATEDIFF ("mi", LASTCHANGE, GETDATE()) > 19
     
     delete from SESSIONS where DATEDIFF ("mi", LASTCHANGE, GETDATE()) > 19
     
     return 
 
 Create Procedure UpdateSession
     (
         @SessionID char (32),
         @data text
     )
 As
     set nocount on
     
     update SESSIONS set DATA = @data, 
         LASTCHANGE = GETDATE() where SID = @SessionID
     
     select LASTCHANGE from SESSIONS where SID = @SessionID

Figure 5   Sample global.asa

 <OBJECT RUNAT=Server SCOPE=Application ID="Sessions"  PROGID="MIND.SessionObject"></OBJECT>
 
 <SCRIPT LANGUAGE=VBScript RUNAT=Server> 
     sub Application_OnStart
         Sessions.Init ("DSN=LocalServer;uid=sa")
         
         Application ("bUseCookies") = True
     end sub
 </script>

Figure 6   iSession.asp

 <%
     '----------------
     ' Session handling routines
     '
     ' by Marco Tabini (1999)
     '----------------
     
     dim UserID
     dim msSession
     dim bUseCookies
     
     bUseCookies = Application ("bUseCookies")
     
     ' Retrieve this user's ID
     
     if bUseCookies then
         UserID = Request.Cookies ("MINDSESSIONID")
     else
         UserID = Request.QueryString ("MINDSESSIONID")
     end if
     
     if Trim (UserID) = "" or IsNull (UserID) then
         ' No ID, create a new Session
         
         UserID = Sessions.CreateSessionID
     end if
 
     ' Update cookie (if cookies are enabled)
     
     if bUseCookies then
         Response.Cookies ("MINDSESSIONID") = UserID
         Response.Cookies ("MINDSESSIONID").Expires = DateAdd ("d", 1, Now)
     end if
     
     ' Load Session
     
     Set msSession = Sessions.Session (CStr (UserID))
     
     '--------------
     ' Use this function to append the Session ID to a URL
     ' if you do not want to use cookies.
     '--------------
     
     Function SessionURL (URL)
         if not bUseCookies then
             if InStr (URL, "?") > 0 then
                 SessionURL = URL & "&MINDSESSIONID=" & UserID
             else
                 SessionURL = URL & "?MINDSESSIONID=" & UserID
             end if
         end if
     End Function
 %>