| The advantages of object-oriented programming systems are well known. In general, object-oriented programming environments do not support long-lived objects, nor do they allow concurrent sharing and dynamic re-use of language defined objects. Persistent object systems address these shortfalls. Persistent object systems extend the conventional object-oriented environment by adding features such as persistence, sharability and dynamic re-usability. These features allow object states and complex object graphs to be stored and retrieved transparently.;This research presents a design and implementation of a persistent object system that uses memory-mapping to directly map objects from the persistent store into the address space of user programs. Memory mapping makes use of advanced operating system support and makes the management and manipulation of persistent objects simpler. In particular, complex object structures can be executed (shared) concurrently on behalf of separately executing applications. Simple language extensions have been designed and added to C++ to make the programming of persistence, sharing, synchronization and consistency control expressible. With effective run-time support for persistent pointer resolution and consistency maintenance, this approach can provide much finer-grain execution concurrency and sharing, easier object navigation, simpler programmability and possibly better performance, than object-oriented database systems. |
