Architectura Mismatch : Why Reuse Is So Hard

my isn't there more progress toward building systems f+om existing parts? One ansueT is that the assumptions of the parts about their intended environment are implicit and either don't match the actual environment oy conflict with those of other parts. The authors explore these problems in the context of their own experience with a compositional approach. F uture breakthroughs in software productivity may well depend on the software community's ability to combine existing pieces of software to produce new applications. The current build-from-scratch techniques that dominate most software production must eventually give way to techniques that emphasize construction from reusable building blocks. If not, software designers may hit a production ceiling in generating large, high-quality software applications. The last decade has seen increased support for compositional approaches to software. There is considerable research and development in reuse; industry standards like CORBA have been created for component interaction ; and many domain-specific archi-tectures, toolkits, application generators , and other related products that support reuse and open systems have been developed. Yet the systematic construction of large-scale software applications from existing parts remains an elusive goal. Why? Some of the blame can rightfully be placed on the lack of pieces to build on or the inability to locate the desired pieces when they do exist. But even when the components are in hand, significant problems often remain because the chosen parts do not fit well together. In many cases these mismatches may be caused by low-level problems of interoperability, such as incompatibilities in programming languages, operating platforms, or database schemas. These are hard