Chapter 3. Operational Profiles: Quantifying Frequency of Use of Use Cases

A use case with many bugs can seem reliable if the user spends so little time running it that none of the many bugs are found. Conversely, a use case that has few bugs can seem unreliable if the user spends so much time running it that all those few bugs are found. This is the concept of perceived reliability: it is the reliability the user experiences, as opposed to a reliability measure in terms of, say, defect density. SRE begins by defining the operational profile of a product: a description of the product's usage patterns that includes frequency of use. This allows the engineering team to optimize development and testing, concentrating on the most frequently used use cases, and hence having a greater chance of failure in the hands of the user.

By taking such an approach, project teams work smarternot harderto deliver a reliable product.

In this chapter, we'll start by looking at building operational profiles for the scenarios that make up a single use case, followed by building operational profiles for a package of use cases. This chapter will conclude by showing you how to extend operational profiles to address risk profiling of use case packages.