Challenges of External Systems

In this lesson, we’ll review the driving force behind the hexagonal architecture approach—the difficulty of working with external systems. Dependencies on external systems cause problems in development. The solution leads to a nice design approach.

Handling external systems

Let’s look at a simple way of handling external systems. The task of our user is to pull a report of this month’s sales from a database. We’ll write one piece of code that does exactly that. The software design looks like this: