A Word of Caution

a particular use case can change in only two ways: Either the sequence itself changes or the activities within the use case change. For example,

One way of performing functional decomposition is to have as many services as there are variations of the functionalities. This decomposition leads to an explosion of services, since a decently sized system may have hundreds of functionalities.

Duration and device volatility.

Assembly Instructions

Make an explicit effort to list the areas of uncertainty in the project and focus on estimating them. Always break down large activities into smaller, more manageable activities to greatly increase the accuracy of the estimations.

Security volatility.

A loosely coupled system design such as that in Figure 7-1 has minimized the number of interactions to the point that removing one interaction makes the system inoperable.

Solutions Masquerading As Requirements