Aspects of version management of composite objects

Sammanfattning:

An important aspect of object oriented database systems is the ability to build up composite objects from objects parts. This allows modularity in the representation of objects and reuse of parts where appropriate. It is also generally accepted that object-oriented database systems should be able to handle temporal data. However little theoretical work has been done on temporal behaviour of composite objects, amd only relatively few systems attempt to incorporate both historical information and composite objects in a multi-user environment.

We argue that the support for handling temporal information provided by other systems addresses only one of two important kinds of historical information. We describe the notions of temporal history and edit history.

In this work we also make a first step in formalizing historical information of composite objects. We identify different kinds of compositions and give formal synchronization rules between a composition and its components to induce the desired behavior of these compositions in a database setting. We also discuss the transitivity property for the part-of relation with respect to the newly defined compositions.

Finally we address the problem of maintaining consistent historical information of a composition using the historical information of its components. This problem occurs as a result of sharing objects between ceveral compositions. We propose a solution and show an implementation in the LINCKS system.