Modern software engineering is mostly concerned with a paradigm of evolutionary systems .Re-Engineering offers an approach to have the evolvable systems rather than legacy systems. The process of reengineering may be applied as engineering principles to an existing system to meet the new requirements of that system .With the view of software reengineering we have discussed its different forms including reverse engineering , data restructuring , program restructuring and source code translation . The purpose of reengineering is to increase the efficiency and decrease the overhead.
INTRODUCTION.
After the half of 20th century, Software Industry has been grown up with tremendous high rate . Now a days softwares are used in almost every organizational activity . These systems should be maintained and evolved according to the new requirements and with the introduction of new hardware .For some systems it has been estimated that the eighty percent of total expenditures are consume just for evolving and maintenance . There is huge backlog of maintenance requests .So some organizations avoid to improve their system. Old systems that are still to be maintained are called "Legacy System". The amount of code in legacy systems is immense. Most of these systems were developed before the use of standard software engineering techniques. Their structure and documentation may be out of date or non existing and may be there is no one to understand them . The risk in re-writing these systems is very high . Organizations do not want their legacy system obsolete .They may afford only its evolution only. "Software Engineering" is concerned with taking these legacy systems and re-implementing them to maintain them . The system may be re documented . It may be translated to a modern language , it may be implemented on distributed system rather than on mainframe and it may be implemented for different database management system.