Legacy systems adaptation using the service oriented approach

Legacy systems are the core IT assets of the great majority of organisations that support their critical business processes. Integrating those existing legacy systems with the rest of IT infrastructure is a complex and difficult task. Legacy systems are often undocumented, inflexible and tightly coupled and imply high cost of maintenance. Many organisations are starting to look at Service Oriented Architectures (SOA) as a potential way to expose their existing legacy investment as functional units to be re-used and exploited externally. This paper is focused on providing guidance to those organisations which want to use SOA on legacy adaptation and transformation. For doing so, this paper defines a vision and a set of best practices that any organisation should follow in order to expose their useful legacy functionalities as part of a SOA environment, allowing the development of hybrid systems understood as compositions of new services as well as of legacy systems and existing components wrapped as services.