Conclusion

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We would like to end this chapter with a few observations:

• When you start a project, you know much less about the business to support and the design model to support it with than you will later. As we've said before, for every day you work on the project, you'll learn more about those things.
• Anybody who believes, under such circumstances, that the early decisions he or she makes about how to design an application are the best possible is heading for trouble.
• Knowing this, you should expect later to change your mind about almost everything you put in your design models. When you do, you should absolutely not feel bad about it. There's no shame in acquiring new knowledge or gaining experience.
• When you do change your mind, the less code you have written the easier it will be to change. Ideally, you make most design changes in your design models, before you have even started to write code.

NOTE

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The likelihood of change is an extremely good reason to design by modeling in the first place. A model in Rose or Visual Modeler is a high-level abstraction of your application, and it helps you clarify how your application's different parts need to relate to and interact with each other. Such a model helps you draw the big picture before you commit your ideas to code. So you make any changes to your design much cheaper to accomplish.

• When, as in our case, there's existing code that needs to be protected, changes aren't as easy to make, and they come at a higher price. To minimize time and money spent on making them, it helps a lot if programmers and designers understand each other well, and if they meet at regular intervals to discuss the experiences they gain from advancing the project. As a rule, if you're mainly a designer you'll do well to learn about the realities of the programmer, and if you're a programmer you should learn as much as you can about design. If all designers and programmers followed such a practice, they'd be able to cooperate much better and also work much more closely together.