Software design patterns and principles

Your will probably be using object-oriented (OO) or functional programming in your microservices or Lambda code, so let's briefly talk about the patterns linked to them.

In OO programming, there are many best practice patterns or principles you can use when coding, such as GRASP or SOLID. I will not go into too much depth as it would take a whole book, but I would like to highlight some principles that are important for microservices:

• SOLID: This has five principles. One example is the Single Responsibility Principle (SRP), where you define classes that each have a single responsibility and hence a single reason for change, reducing the size of the services and increasing their stability.

• Package cohesion: For example, common closure-principle classes that change together belong together. So when a business rule changes, developers only need to change code in a small number of packages.
• Package coupling: For example, the acyclic dependencies principle, which states that dependency graphs of packages or components should have no cycles.

Let's briefly go into some of the useful design patterns for microservice:

• Creational patterns: For example, the factory method creates an instance of several derived classes.
• Structural patterns: For example, the decorator adds additional responsibilities to an object dynamically.
• Behavioral patterns: For example, the command pattern encapsulates a request as an object, making it easier to extract parameters, queuing, and logging of requests. Basically, you decouple the parameter that creates the command from the one that executes it.
• Concurrency patterns: For example, the reactor object provides an asynchronous interface to resources that must be handled synchronously.

Depending on you coding experience, you may be familiar with these. If not, it's worth reading about them to improve you code readability, management, and stability, as well as your productivity. Here are some references where you can find out more:

• SOLID Object-Oriented Design, Sandi Metz (2009)
• Design Patterns: Elements of Reusable Object-Oriented Software, Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides (1995)
• Head First Design Patterns, Eric T Freeman, Elisabeth Robson, Bert Bates, Kathy Sierra (2004)
• Agile Software Development, Principles, Patterns, and Practices, Robert C. Martin (2002)