A strategy and toolset (FixIT) for migrating a specific type of legacy systems - based on the FileMan DBMS of the US. Department of Veterans Affairs - to a two-tier client/server and web browser-based architecture was presented in MEDINFO'98. In the current paper we discuss the further migration to a multi-tier software component architecture. A literature survey and industry contacts were used to specify an open, component-based target architecture for healthcare information systems to be reached by the year 2005, as well as a phased migration strategy from the present FileMan/FixIT-based systems towards the target. The target architecture is based on large-grained business components and accommodates heterogeneous elements on the intra-component, intra-application, intra-organization and inter-organizational levels. Four logical tiers are identified within a business component, Three migration paths are specified for different cases: the tier-by-tier, piece-by-piece, and web-wrapping paths. It is argued that the architecture, supported by off-the-shelf toolsets, application frameworks and a new software development process, makes it possible to turn legacy systems into a valuable asset, split monolithic applications into reusable components, and ultimately replace the legacy parts at a feasible pace.
