Relationship between VistA Novo and EWD
VistA Novo Components
VistA Novo is an open source toolkit developers can use to build VistA-based applications using mainstream development tools. It consists of three primary components:
- Service Invocation component to access VistA functions and data.
- Data Storage component to make available test data for development purposes during build-time and to cache data locally for performance optimization during run-time.
- FHIR Service component to expose VistA data following the FHIR specification.
VistA Novo interaction with VistA-based services within a VA environment
The first picture illustrates the current focus of VistA Novo within a VA environment, where the VistA Novo FHIR Implementation invokes VistA-based Services that sit on top of the Cache Suite to make available VistA data following the FHIR specification. These VistA-based services may be generated using the VistA Service Assembler or via other means. The Testing Stub (also being developed under the VistA Novo project) provides an initial service interface that mocks the behavior of future/under development VistA-based services for testing purposes.
VistA Novo interaction with VistA-based services within an open source environment
The second picture illustrates how the FHIR Implementation can be used on top of an open source stack, including GT.M and EWD. The notion is that VistA-based services would be developed using EWD. Whether the VistA-based service back-end is based on Cache or GT.M and EWD is transparent to the FHIR Implementation.
VistA Novo interaction with EWD
Comparison of a VistA-based Services vs. Enterprise Web Development Approach
VistA-based Services Layer:
- Supports data federation across VA sites,
- Abstracts complexities of VistA MUMPS routines
- Exposes authoritative, business services meaningful to consumers
- Potential challenges with maintainability (duplicative services, etc.)
- Potential performance issues
- Performance benefit, removes one extra service invocation
- Lean architecture, fewer moving parts
- Requires expertise in VistA and to understand nuances in MUMPS routines, working in same execution space with access to MUMPS routines
Transition from VistA-based Services to an EWD-based Approach
There are a number of components that need to be updated in VistA Novo to go from a VistA-based Services approach to an EWD-based approach. The figure below illustrates the changes.
The FHIR Services component remains unchanged.
Transition to an EWD-Based Approach Summary
Presently, VistA Novo is targeted to provide a VistA Developer Toolkit that allows both VA and open source developers to:
- Consume VistA data in a format that follows the FHIR specification
Level of Effort:
- FHIR Services component: None
Need to revisit VA-specific considerations, including federation across multiple VA medical centers and the desire for authoritative business services.
Any comments/edits to the depictions above are welcome.