The majority of Department of Veterans Affairs (VA) healthcare computing involves Veterans Health Information System and Technology Architecture (VistA) and applications integrated with VistA. The increasing need to integrate VA computing systems across business domains and with external systems such as Department of Defense (DoD) has taken precedence in bridging the technical gap between legacy VistA and disparate technologies of Commercial-Off-The-Shelf (COTS) products. In addition, the VA healthcare Service Oriented Architecture (SOA) currently faces challenges in efficiently exposing existing VistA methods and data, providing "services" for use by other systems and technologies, and decoupling consuming systems from the implementation details of VistA. OIT/PD has defined VSA as a new design approach for providing SOA compliant integration between VistA applications and external systems.
VSA facilitates a solution that provides the ability to expose VistA functionality as SOA compliant web "services" directly, and ways to integrate legacy system VistA to external systems and applications. With VistA as an SOA service provider, these services utilize VistA application business logic directly, thus eliminating redundancy and leveraging existing, tested VistA application functionality. The VSA solution will provide utilities to automate the creation of VistA SOA services, and the infrastructure components necessary to support and operate those services. VSA will identify and produce sample VistA SOA business services as "reference implementations", based on consideration of major organizational initiatives that have a need for VistA SOA services in the near future. VSA achieves to address SOA objectives and provide the ability for VistA applications and services to become economically extensible and maintainable, individually replaceable, and fully compliant with SOA architecture.