Rapid Conversion Of The Huge Software Legacy System

With the development of computer software industry, many huge systems have been developed in the last several decades using different software technlogy., As the new technology came out very soon in software industry, a lot of legacy systems need conversion. In the old days,a lot of software companys did not notice the importance of software engineering, many legacy software systems are lack of detailed deisign documents.How can we finish the conversion of the legacy ststem in a short time? How can we ensure the reliability of the new system and do the minimal modification in the old system? It will helpful if we can organize some guildlines for legacy system conversion.In this paper, firstly, we will introduce a improved method to do the reverse engineering.we can figure out the flow path of the legacy system after the reverse engineering . then, we will introduce a Procedure for the ANSI-based system conversion, many legacy systems did not use distributed technology,we will introduce a method to do minimal modification on the system and implement the distribution system,at last,we take mfc legacy sysyem as the example, and introduce a method we can using the unmanaged code in the manged system.