Designing an aggregate with the right boundaries and clear responsibilities is not a trivial task. A lot of times people rely on gut feeling or implicit heuristics to guide modelling decisions. Depending on these decisions and chosen consistency boundaries, we might be able to enforce business invariants or will have to put some corrective policies in place. Because of that, it is important to evaluate multiple designs of the aggregates, as they impact behaviours modelled within our domain.

During the workshop, you will have an opportunity to model and document an aggregate in practice using the Aggregate Design Canvas. It is a tool created to guide your modelling process, make the design decisions explicit, reason about concurrency conflicts and the size of data persisted in the underlying storage. The goal of the lab is to model an aggregates used in healthcare booking system, and we need your help to decide whether it should be a single slot, a whole year worth of slots or something in between!