Architects must watch out for composite architecture characteristics—ones that aren’t objectively measurable but are really composites of other measurable things. For example, “agility” isn’t measurable, but if an architect starts pulling the broad term agility apart, the goal is for teams to be able to respond quickly and confidently to change,

Building services that model bounded contexts required a subtle but important change to the way architects designed distributed systems because now transactionality is a first-class architectural concern. In many of the distributed systems architects designed prior to microservices, event handlers typically connected to a single relational

Each understands the common scope under question: architects understand the coupling characteristics, developers understand the scope of behavior, and the operations team understands the deployable characteristics.

While experience is useful, scenario analysis is one of an architect’s most powerful tools to allow iterative design without building whole systems. By modeling likely scenarios, an architect can discover if a particular solution will, in fact, work well.

The authors built many distributed systems a few decades ago when they first became popular, yet decision making in modern microservices seems more difficult, and we wanted to figure out why. We eventually realized that, back in the early days of distributed architecture, we mostly still persisted data in a single relational database. However, in

An architect implements fitness functions to build protections around unexpected change in architecture characteristics. In the Agile software development world, developers implement unit, functional, and user acceptance tests to validate different dimensions of the domain design. However, until now, no similar mechanism existed to validate the

Dynamic coupling Represents how quanta communicate at runtime, either synchronously or asynchronously. Thus, fitness functions for these characteristics must be continuous, typically utilizing monitors.

High functional cohesion refers structurally to the proximity of related elements: classes, components, services, and so on. Throughout

static coupling analyzes operational dependencies, and dynamic coupling analyzes communication dependencies.