Implementing Domain-Driven Design

Estimating Aggregate Cost

As Figure 10.7 shows, each Task holds a collection of EstimationLogEntry instances. These logs model the specific occasions when a team member enters a new estimate of hours remaining. In practical terms, how many Task elements will each BacklogItem hold, and how many EstimationLogEntry elements will a given Task hold? It’s hard to say exactly. It’s largely a measure of how complex any one task is and how long a sprint lasts. But some back-of-the-envelope (BOTE) calculations might help [Bentley].

Task hours are usually reestimated each day after a team member works on a given task. Let’s say that most sprints are either two or three weeks in length. There will be longer sprints, but a two- to three-week time span is ...