ABSTRACT
Software reuse has been effectively practised at the implementation level for many years in the form of code libraries, e.g. COBOL Data division libraries, FORTRAN modules from the National Algorithms Group. Interest in reusability was targeted on program development and this achieved modest results in terms of small scale modular reuse. Barriers can be either technical or social in nature. Technical barriers include problem of finding and matching reusable components to a new application context; the design problem of composing a system from reused components; and the impact of more general software engineering problems on the reuse area. Reuse can be happen at a variety of levels and several different interpretation have been reported. For instance reuse has a dimension which maps approximately to the system development life cycle: Implementation level reuse: reuse of code modules, already an established practice. As reuse progress up the life cycle dimension, the difficulty and hence cost of solving the problem increases.
