At the end forward engineering is carried out. It means incorporating the new business processes and rules in the system. Forward engineering requires application of SE principles, methods, and concepts to re-create an existing application. In most cases forward engineering does not simply create a modern equivalent of an older program, rather new user and technology requirements are integrated into the reengineering effort.
A system is considered to be a legacy system if it has been in operation for many years. A legacy system has many components. These include business processes, business rules, application software, application data, support software, and system hardware. The relationship among these components is shown in the following diagram.