The operational semantics of user-defined relationships in object oriented database systems

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摘要

In semantic data models, abstract relationship (e.g. generalization, aggregation, etc.) semantics are defined, specifying how insertion, deletion and modification operations made at a higher level of abstraction can affect the objects abstracted over and vice versa. These semantics, also known as structural constraints, are expressed through so-called update rules. This perspective has been somewhat lost in most object-oriented systems, where user-defined relationships are supported as simple pointers and their semantics are embedded, distributed and replicated within the operations accessing these pointers. This paper inherits and extends the treatment of relationships found in semantic data models to behavioural object-oriented models by presenting an approach to uniformly capture the update rules for user-defined relationships. The stress is not on supporting relationships as first-class objects, but on describing their update rules (or operational semantics) through a set of constructors namely, reaction, anticipation, delegation and exception. The approach has been borne out by an implementation in an active object-oriented database system.

论文关键词:Conceptual modeling,Object orientation,Active databases

论文评审过程:Received 25 July 1994, Revised 24 February 1995, Accepted 4 May 1995, Available online 22 December 1999.

论文官网地址:https://doi.org/10.1016/0169-023X(95)00015-K