Simplifying Complex Back-End Logic

Problem statement

Let’s imagine that we’re dealing with a whole range of complex classes, all of which we’d need to access from a single layer of our application. It could be, for example, code that has been auto-generated from a WSDLWeb Services Description Language definition. It could also be some manually written code where different classes retrieve data from different data sources.

This scenario is very typical because it uses the commonly used multilayer architecture. In such architecture, there’d be a separate layer responsible for presentation, a separate layer responsible for back-end business logic, and a separate layer responsible for data storage. In real-life applications, however, it often isn’t as simple as this. The application might be retrieving its data from multiple sources, such as several different database ...