Improving the legacy systems by Re-engineer

Re-engineering in IT means extracting the business logic and data from current systems then moving to new system. The term “re-engineering” have different meaning with the term “business process re-engineering” or “BPR”. The “system re-engineering” refers to software only while BPR refers to redesigning the business processes.

People thinks existing systems as a debt that have to be maintained, and avoid developing the new, exciting systems. That thinking way is the main problem in IT management. Instead, management team needs to understand the existing systems as asset. When developer can reverse engineer a system, to extract the underlying business logic, they can forward engineer that logic to new system.

Charles Bachman proposed a new system development life cycle, which can include all four basic activities: maintenance, enhancement, new development and migration. This life cycle presents on circular.

As in case study of GTE Directories, a company in advertising industry with Yellow Page product, they have four legacy systems/databases. These databases were designed application-by-application at original, so they didn't have any business relationship to each other. The management team decided using reverse engineering tools to help them improve databases. A designer modelled existing database to graphical then made changes by manipulating icons. The reverse engineering tool helped to draw complete and consistent relationship diagrams. Once new databases design had been created, the designer forward engineered the database design to generate database statements.