Posts in category 'design'


Streaming Data to Reduce Memory Usage

I recently performed a series of optimizations to reduce an application’s memory usage. After completing several of these I noticed that there was a common theme to many of my optimizations that I could explicitly apply to help identify further opportunities for improvement. As a reoccuring solution, this qualifies as a design pattern which I […]

Exploring Mental Processes behind Developing Software

How do you go about designing and coding software? More specifically, what is your mental process for accomplishing this? Becoming more aware of the approach you use allows you to deliberately control and improve it. Mental thought processes are, however, very intangible and difficult to put into words. In the software development literature much has […]

Exposing Mutable Objects as Public Properties

I recently had an interesting design discussion with a coworker in which we discussed the pros and cons of exposing mutable objects as public properties of a class. This article provides my thoughts on the subject. An immutable class (or object) is one whose state cannot be changed once the instance is constructed. Mutable objects […]

The Source Code is the Design

I first came across the thought-provoking article What Is Software Design? by Jack Reeves as an appendix titled “The Source Code Is the Design” in the book Agile Software Development: Principles, Patterns, and Practices The article was written in 1992 so ignore the references to C++ (I mentally translated them to Java) and instead focus […]

Inspiring Great Design

I recently acquired a design tool – a set of IDEO method cards, where each card presents a design approach or a method of gaining inspiration. IDEO’s design philosophy is to keep people at the center of the design process, and the four categories they divide the cards into reflect this: Ask people to help. […]

Designing for Deployability

In my previous article Architecting for Deployability, I wrote about the importance of deployability – how reliably and easily software can be deployed from development into the production environment. To accomplish this, one approach I recommended was to encapsulate differences between environments to isolate them from the majority of the application, and thus simplify deployment. […]

Error Handling and Reliability

I have been thinking a lot lately about how to create reliable systems. I previously examined the link between complexity and reliability. Recently, however, I have come to appreciate the impact of error handling on reliability. For the purposes of this discussion, I consider two aspects of reliability: correctness – does the application produce the […]

Complexity and Reliability

Unrestrained complexity is a critical limiting factor in producing working software. The more complex a system, the more it will cost to create and operate and the less reliable it will be. Yet the bane of complexity is largely ignored by the IT industry. Software vendors, competing on the basis of feature sets, are constantly […]

The Reuse Trap in Software Design

I stared at my code on the screen, but inspiration wouldn’t come. I was trying to design a new feature which shared some commonalities with the existing code base. In particular, there were a couple classes that I knew I could reuse. I just wasn’t sure how they would have to be modified because I […]

Fail Fast or Degrade Gracefully?

There are two approaches to handling internal application errors. In the fail fast approach you immediately terminate the operation (or even the application) once an error is detected. In the degrade gracefully approach you try to continue with as much of the operation as you can. For quite a while I have been a firm […]