13.2 What we try to achieve

What we try to achieve

Requirements seem to be a simple thing. They are often overlooked, even from people that buy into analysis and object modeling. Nevertheless, requirements are the very base of every application. How can you analyze a problem if you don't even know about it? How can you know about the customer's business unless you talk to him? You can save yourself a lot of trouble by simply spending a little more time collecting requirements to make sure everybody fully understands the situation.

Requirements have a very unpleasant characteristic: they are constantly changing. This will influence your project throughout its lifecycle. The later in the cycle that changes have to be made, the harder those changes will be to make and the worse they are for the morale of the troops. Unfortunately, changes are usually more frequent later in the cycle, simply because it has been quite a while since the original requirements were put together and the world has been changing since then.

What you need is a simple way to collect requirements, manage changes, and trace them to use cases, models and the implementation. This will help to predict the impacts of changes before implementing them. It will also help to find all the places that are affected by a change. In this chapter, I introduce techniques that help to resolve these issues.