Performance Properties of Vertically Partitioned Object-Oriented Systems.

It has long been believed that object-oriented system structuring offers advantages for design and implementation of computer software systems with respect to comprehensibility, verifiability, maintainability, etc. The major obstacle to widespread use of object- oriented systems has been that their execution has been intrinsically inefficient due to excessive overhead. This paper contends that much of the execution overhead of object-oriented systems has been due to the implementation structure, that is, the objects are built upon a conventional layered software structure. This paper proposes a vertically partitioned structure for design and implementation of object-oriented systems and demonstrates their performance. We show that the application independent portion of the execution overheads in object-oriented systems can be less than the application independent overheads in conventionally organized systems built upon layered structures. Vertical partitioning implements objects through extended type managers. An extended type manager not only implements the functionality which defines a type but also implements all state management functions such as storage, access control and consistency management (including concurrency control, error detection, and fault recovery) for the occurrences of that type. Two key design concepts result in performance improvement: object semantics can be used, in the state management functions of an object type and atomicity is maintained at the type manager boundaries providing efficient recovery points. The performance evaluation is based upon a case study of a simple but nontrivial distributed real-time system application. Evaluation of overheads was accomplished by implementing system control, but not implementing application functionality for both conventional layered and vertically partitioned versions of the application. The results show a clear diminution of overhead in the vertically partitioned, object-oriented structured system over the functionally oriented, layered structured system. [ABSTRACT FROM AUTHOR]