Application reengineering is considered when existing legacy applications enjoy properties worth preserving. They are already deployed and have usually undergone significant scrutiny by their users. A long history of maintenance results in "stress-hardened" code and a wealth of test and validation capabilities, which, however, causes a problem: the system becomes "brittle" and increasingly resistant to change and may lack many of the features of more modern ones.

The BitWise Application Migration/Modernization Practice provides organizations with the ability to utilize their existing IT investments while leveraging the benefits afforded by newer technologies - J2EE, .NET, Open Source, XML.

By leveraging over 1500 combined years of software development experience, multi-shore specialized services and proven delivery methodologies, BitWise is uniquely positioned to meet the requirements of our customers for modernizing and transforming legacy applications. BitWise's mature and flexible processes, combined with domain expertise reduce the risk of modernizing legacy systems and result in a timely, cost effective project that delivers a rapid

For modernizing legacy applications we see four broad strategy options, apart from re-engineering/re-writing all these applications.

• The first strategy with least effort, cost, time and change to applications is to simply update and optimize performance of the legacy system. This includes evaluating all system software (operating system, OLTP etc), databases and applications currently deployed in production to ensure that their advanced features are used to enhance usability, productivity, performance and interoperability with other applications/platforms.
  
   
• The second strategy is to keep the business logic in the legacy applications, while providing the user with a more "friendly" interface to data such as GUI screens or Web browser.
  
   
• The third strategy is to integrate the legacy applications including the business logic with new technologies while (most of) the data resides on the legacy platform.
  
   
• The fourth most intensive approach (short of re-engineering or rewriting the applications), is to migrate part of the mainframe applications to a different platform with little or no change to core business logic. Here the data may/may not be migrated.
   

Constraints of budget, time, resources and risk management compel businesses to modernize mainframe applications by implementing one of the four strategies mentioned above. Option 2 or 3 or combination of both has been found to be the popular strategy.