A highly critical factor in the success of a project is whether the project is entirely new. New software treads in new territory and rarely works on the first try.
In 1970, Winston Royce said one should plan for the first fully deployed system to be the second one created. The first is a prototype that flushes out the critical design issues and proves the concept. You should expect to spend 25% of your time and effort in making the prototype. Fred Brooks reiterates Royce's advice in the Mythical Man Month saying, "Plan to throw one away; you will anyway."
When developing a new software application:
- Plan to build a series of throwaway prototypes before starting the final product.
- Build the Right Kind of Prototype
- Build the Right Features into a Prototype
- Build Throwaway Prototypes Quickly
- Expect a software application to be modifiable for a certain period of years, after which it will need to be fully replaced.
- Software Will Continue to Change*
- Software's Entropy Increases*
- Fix Problems, Not Symptoms*
- The System's Existence Promotes Evolution*
- You can only fiddle with an application just so much before it becomes unstable and must be replaced.
- Software's Entropy Increases*
- The Older a Program, the More Difficult It Is to Maintain*
- Maintenance Causes More Errors Than Development*
- Belief That a Change Is Easy Makes It Likely It Will Be Made Incorrectly*
