Better Software Design — Subscription Services Architecture: Solid Principles Part 1

In Object-Oriented Computer Programming, SOLID is a mnemonic acronym for five design principles intended to make software designs more understandable, flexible, and maintainable. The principles are a subset of many principles promoted by American software engineer and instructor Robert C. Martin, first introduced in his 2000 paper Design Principles and Design Patterns.

The SOLID concepts are:

• The Single-responsibility principle: “There should never be more than one reason for a class to change.” In other words, every class should have one and only one responsibility.

Single Responsibility Principle In Context of Subscription Services. Reference is taken from The S.O.L.I.D. Principles in Pictures by Ugonna Thelma.

• The Open-closed principle: “Software entities … should be open for extension, but closed for modification.”

Open-Closed Principle In Context of Subscription Services. Reference is taken from The S.O.L.I.D. Principles in Pictures by Ugonna Thelma.

• The Liskov substitution principle: “Functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it”. We should follow the idea and concepts that are covered in a concept called: Design by contract.
• The Interface segregation principle: “Many client-specific interfaces are better than one general-purpose interface.” Be specific and objective than being broad and subjective.
• The Dependency inversion principle: “Depend upon abstractions, [not] concretions.”

The SOLID acronym was introduced later, around 2004, by Michael Feathers.

Although the SOLID principles apply to any object-oriented design, they can also form a core philosophy for methodologies such as agile development or adaptive software development.

References:

1. Geeks for Geeks
2. The S.O.L.I.D Principles in Pictures by Ugonna Thelma