AN ARCHITECTURAL BASIS FOR EVOLVING SOFTWARE SYSTEMS

The complexity and the volatility of requirements for large-scale software systems, and the vast in-place investments, make evolution a necessity. With evolution there is risk that critical user objectives will not be met within schedule and funds budgeted for new capabilities. To ensure that mission needs are satisfied, the evolutionary process must be strongly influenced by users, but also carefully controlled by buyers and efficiently carried out by builders. This article discusses how architectural approaches add value by providing, from multiple perspectives, a vision of objectives that is understandable to users, buyers, and builders alike. It then describes how these same approaches also offer a means to organize the evolutionary engineering activity around information needs for the target system. The article illustrates this and shows that use of an ''information architecture'' helps to ensure that results meet ultimate mission needs by focusing engineering activities on the needs of the end user.