18.2 Use Commercial Components

The use of commercial off-the-shelf (COTS) products as elements of larger systems is becoming increasingly commonplace. Shrinking budgets , accelerating rates of COTS enhancement, and expanding system requirements are all driving this process. The shift from custom development to COTS-based systems is occurring in both new-development and maintenance activities. If done properly, this shift can help establish a sustainable modernization practice.

In general, incorporating off-the-shelf infrastructure products, although never painless, has great benefit in providing a standard infrastructure that can be more easily integrated with other systems and components, better quality of service, and more reliable and scalable communications. Off-the-shelf components that offer capabilities in domain-specific areas can also have a positive effect but are more difficult to integrate because they often require changes to existing business processes.

The SEI COTS-based systems (CBS) initiative is exploring the challenges of assembling systems from preexisting components, evaluating COTS products, and modifying legacy systems to take advantage of a CBS strategy. ^[1] The book Building Systems from Commercial Components [Wallnau 01] describes some lightweight, agile development processes for building COTS-based systems. Much of the philosophy underlying these processes is present in this book as well. In many ways, these two books could be considered companion volumes .

^[1] See http://www.sei.cmu.edu/cbs.