Conclusion

We have developed several atomic patterns and SAPs that incorporate principles of good design, and we are producing a catalog of analysis patterns that can be used to produce good-quality conceptual models even by inexperienced designers. All this can be used as a basis for XP development, where the SAPs can guide each stage by relating the partial implementations to the complete system model. This global model can be used as a reference to decide about aspects such as distribution, security, and other nonfunctional aspects. The incremental nature of XP is likely to produce redundancies, and a global model can prevent many of them. SAPs are being tested with students at two universities, but industrial tests are necessary. Initial results have shown that students learning object-oriented concepts can develop rather complex models using SAPs. What we need to verify next is that having these conceptual models helps XP build more complex systems.