计算机英文期刊原文.doc

The face of the object system maintainability abstract: Empirical evidence for the maintainability of object-oriented systems is far from conclusive,partly due to the lack of representativeness of the subjects and systems uesd in earlier studies.We empirically examined this issue for mission-critical software that was currently operational and maintained by software professtionals.Two functionally equivalent versions of a credit approval system were maintained,one object oriented (OO) and the other non-object oriented (NOO).We found that the OO group took less time to maintain a greater number of software artifects than its NOO counterpart,This difference held for all phases of the software development lift cycle.This result was due to the usefulness of UML for impact analysis of the OO version,which contributed to effective comprehension and communication.Insufficient design specifications for the NOO version led to ambiguity and costly defects in transferring design solutions to development.Also the encapsulation of the OO version appeared to reduce mental loads for maintenance tasks and resulted in code reuse.On the other hand,the number of files to be managed increased and,thus,dependency management was required for the OO version.Furthermore,despite much tuning,the OO version ran slower than its NOO counterpart.More field studies on software professionals are needed to compare contextual factors such as methods,processes,and maintenance tools. It is widely believed that use of the object-oriented paradigm incresases software maintainability (Johnson,2000).However,this supposed benefit has not as yet been experimentally balidated.A number of empirical studies have been performed to address this issue,but the results to date have been inconclusive (Johnson,2002).Furthermore,virtually all the studies have been conducted in a well-controlled laboratory setting on software specially developed for the experiments,and it is not clear that these results can be ext