Assembling off-the-shelf components: "Learn as you Go" systems engineering

The process of developing new information systems has evolved from custom software development to assembly of off-the-shelf components. The change has significantly reduced both the costs and time to develop new capabilities, and as a notable result, e-business systems have been implemented at a very rapid pace. An assembly sequence (components to be assembled, corresponding dates and costs) has several risks including: 1) technical risk: successful (or not) function of assembled components by planned schedule milestones; 2) operational risk: achieving (or not) the desired business value by using the new system of assembled components; and 3) programmatic (schedule and cost) risks: accomplishing the assembly within time and budget constraints. As assembly proceeds, estimates of technical performance and operational value at the time of system completion can be adjusted, and one should consider what early milestones of component assembly suggest about later milestones. The technical community can be both hesitant to reveal and ascertain the results of combining off-the-shelf products into a working system, and it is typical to have significant cost and schedule overruns due to technical problems that are discovered late in system assembly. The operational community can be surprised by the results achieved in applying new capabilities, causing significant changes to what was originally desired from a new system. This paper presents a framework for planning and adjusting milestone sequences in assembling off-the-shelf software components. The framework balances technical and operational risks within established cost and time constraints.