2.8 Basic features of a session model

The Frame Application has to implement a session model for multi-user support, for safe data management and for data consistency.

Typically a session starts at the start of a DTM on the user interface of the Frame Application and is closed at the termination of the DTM. If there is a second DTM started by the user within the Frame Application, it creates a separate session.

All data objects that are opened inside such a DTM are registered in its session. At the end of the session all modified data of the session have to be stored synchronously (if the user wants to save modifications).

A data object is locked if a DTM opens it with write access. While data are locked by a DTM, other DTMs have only read access, but no write access.

A session can be created with or without the right for locking data within the session. If it is created without that right, DTMs are not allowed to lock data in this session. The Frame Application creates the session without that right, if the DTM is started with an function Id or a user role which does not allow modification of data. In all other cases it opens the session with the right for locking data.