design patterns

Bertrand Meyer first introduces the principle of Command Query Separation in his book Object-Oriented Software Construction. The principle states that a well designed object should have methods that are either commands or queries. A command changes the state of an object, but does not return any data, while a query returns data and does not change any state. By dividing methods into these two categories, you will have a better understanding of what does, and what does not, change the state of your system....

I recently finished reading the excellent book “Release It!” by Michael Nygard. One of the key points that I wanted to remember was the stability anti-patterns. So, this post will serve as a reminder of architectural smells to look out for when designing production systems. This list of anti-patterns are common forces that will create or accelerate failures in production systems. Given the nature of distributed systems, avoiding these patterns is not possible....

Early pioneers in object-oriented programming paved the path towards using Model View Controller (MVC) for graphical user interfaces as early as 1970 and web applications have continued using the pattern to separate business logic from display. This article attempts to clarify the use of Model View Controller within web applications — giving consideration to the fact that most developers will be building their application using an existing web framework. ...