Persistence layer

1. An apparatus comprising:

a database;

a hardware memory;

a persistence layer to control access to the database by an application, the persistence layer having an update table residing in the memory to retain transaction data from the application before the transaction data is committed to the database, wherein the persistence layer has a simulation mode and wherein transaction data is persisted to a buffer responsive to an update command rather than the database when the persistence layer is in the simulation mode; and

a session context applied to the persistence layer the session context to define a condition for writeback to the database.

2. The apparatus of claim 1 wherein the persistence layer comprises:

a persistence manager to write a content of the update table to the database after all business logic in the application has completed processing of the transaction data.

3. The apparatus of claim 1 further comprising:

a plurality of data specific persistence managers instantiated by the persistence layer; and

a buffer in the memory associated with each data specific persistence manager.

4. A method comprising:

receiving database updates in a persistence layer between an application and a database;

aggregating the database updates from the application as persistence objects in an update table;

delaying a writeback to the database based on a session state of the persistence layer;

entering a simulation session in the persistence layer; and

writing the updates to a buffer rather than the database responsive to an update command during the simulation session.

5. The method of claim 4 further comprising:

permitting an overwrite of the buffer without writing back to the database when after the simulation session is complete.

6. The method of claim 4 further comprising:

writing back the persistence objects from the update table after all business logic in the application has completed processing corresponding transaction data.

7. The method of claim 4 further comprising:

prefilling a buffer with data from the database expected to be needed by the application; and

sourcing the data to the application from the buffer via the persistence layer.

8. The method of claim 4 wherein delaying comprises:

preventing database updates after a first execution of the application until a successive execution of the application on the data completes.

9. The method of claim 4 further comprising:

aggregating database updates from execution of a second application with the database updates of the application to avoid writing back temporary data to the database.

10. A non-transitory machine-accessible medium containing instructions that when executed cause a machine to:

receive database updates in a persistence layer between an application and a database;

aggregate the database updates from the application as persistence objects in an update table; delay a writeback to the database based on a session state of the persistence layer;

enter a simulation session in the persistence layer; and

write the updates to a buffer rather than the database responsive to an update command during the simulation session.

11. The non-transitory machine-accessible medium of claim 10 further comprising instructions causing the machine to:

permit an overwrite of the buffer without writing back to the database when after the simulation session is complete.

12. The non-transitory machine-accessible medium of claim 10 further comprising instructions causing the machine to:

writeback the persistence objects from the update table after all business logic in the application has completed processing corresponding transaction data.

13. The non-transitory machine-accessible medium of claim 10 further comprising instructions causing the machine to:

prefill a buffer with data from the database expected to be needed by the application; and

source the data to the application from the buffer via the persistence layer.

14. The non-transitory machine-accessible medium of claim 10 wherein instructions causing the machine to delay includes instructions causing the machine to:

prevent database updates after a first execution of the application until a successive execution of the application on the data completes.

15. The non-transitory machine-accessible medium of claim 10 further comprising instructions causing the machine to:

aggregate updates from execution of a second application with the updates of the application to avoid writing back temporary data to the database.