فرآیند مهندسی مجدد و الگوهای آن REENGINEERING and REENGINEERING PATTERNS

۱٫ PREFACE We have made a report about reengineering and reengineering patterns. The report is part of the course Object Oriented Programming fk at Mälardalen University. At the beginning, when we choosed the subject reengineering patterns, we did not have any specific knowledge about what it actually meant. We started to search for information at the Internet, but it wasn’t so much information there as we had hoped, most of the information were similar or not the kind of information that we were looking for. Finally, we located some sites that were of interest to us in our work. When we had read some articles and publications we started to understand what reengineering and reenginering patters really is. By discussing with each other in the group we found specific areas that we thought were particulary interesting. Now, when we knew a little bit more about reengineering and reegnineering patterns, we decided to begin writing our report. Because the time of the project have been limited and that it has been hard to find information it was difficult to pass the deadline. But even if we think it has been quite hard we also think that we have learned a lot about the concept of reengineering. 2. ABSTRACT Reengineering and Reengineering patterns is a relatively new concept that has begun to make an impact on the software engineering sociaty. By shifting resources towards the restructuring of old legacy software systems rather than focusing on new software development the businesses would and have been able to save precious time and resources. Even though the benefits of this approach is clear, the difficulties that follows with the concept, together with inexperience and the lacking of appropriate tools make the reengineering of software systems a difficult but interesting subject. 3. THE HISTORY OF THE REENGINEERING CONCEPT In early years of the information revolution the need for reengineering was not acknowledged by the wider community. Instead, attention was directed towards the discovery of new ways of creating both better hardware and better software. Methodologies that were concerned with how to engineer the development of new systems where published, cheered and disposed in an ever increasing rate. Almost no attention were given to the old systems that were getting more and more outdated. In addition, the businesses where changing rapidly and with them came the need for appropriate information software. This became known as ‘software shortage’; since there always seemed like newly devoloped software where not good enough to accommodate the business needs. Then, in the early 90’s the focus of system devolopment changed very rapidly from the development of new software to the reengineering of old ‘legacy’ systems (systems developed over time and in need of maintainance). The fact is, that so much attention where given to reengineering that entire businesses where cought up in the excitement and had their entire business structure reorganized according to the newly developed reengineering methodologies and patterns that had emerged. Reengineering was the word of the day and the reengineering consultants where having a field day [BPR 99]. But soon it became appearant that the reengineering of both business and it’s software where not as easy as the consultants had first believed. Over half of the reengineering processes of the time failed, mostly due to inexperience and lack of customer involvement. With these failures followed huge costs for the companies and soon the reengineering boom was over, and with it the interest in reengineering devolopment [BPR 99]. Still, almost 80% of a business information system budget costs comes from the maintainance of old legacy systems. That means only 20% of the total cost can be related to the development of new systems [SR]. This shows that reengineering, the reorganization and redesign of a system (or business), is very important; since if these costs can be reduced, much will be gained for the software user. This fact has contributed to the return of an active reengineering research community, and as we enter the 21st century we see that reengineering is once again marching forward into the frontlines of software engineering.