A mixed application model supports a business application that manages data transactions that span multiple requests (session-managed), while at the same time supporting an atomic request model for client operations that stand alone, such as independent queries on the data (session-free).

If your application requires a mixed application model, you have to identify the application model and client binding of each client request before servicing it, because any PAS for OpenEdge session can handle requests for clients running in any application model when the session is not bound to a single session-managed client. This makes the business application code more complex, especially for event procedures you have configured to manage client and session context across client connections and requests.