1 Introduction

In the Mjølner System, objects generated by a BETA program execution may be saved on secondary storage and restored in another BETA program execution. Usually this property of a programming language or system is referred to as object persistence. Persistence in the Mjølner System is based on a reachability model, meaning that default behaviour when saving an object on secondary storage is to save everything reachable from the object in question.

Mjølner supports a single-user persistent store model as well as a multi-user shared persistent store. The multi-user persistent store makes it possible to build an object-oriented database (OODB) using a clienter/server model. Persistence in Mjølner is based on a number of frameworks:

In addition to the above main features, the following features are also supported: The persistence frameworks have gone through a number of iterations: The new basic object management will eventually replace the old basic object management. In release 5.0 of the Mjølner System the old- as well as the new basic object management are included. We recommed to use the new basic object management since it is much more efficient than the old one. However, as this is the first release of the new basic object management, there may still be some errors or problems that have not yet been discovered.

The old and the new basic object management both work with the shared persistent store.

The directory

contains the new basic object management as well as the shared persistent store.

The directory

contains the old persistent store.

The interface to the old and the new persistent store is the same. That is, it is possible to alternate between the old and the new store by including either




Persistence in BETA - Reference Manual
© 1991-2002 Mjølner Informatics
[Modified: Monday October 23rd 2000 at 10:43]