VistA Imaging Services Architecture VISA

1. 1 VistA Imaging Services Architecture (VISA) Class 764 Julian Werfel

2. VistA Imaging System evolved since late 1980s Collection of client and server applications Image and Text Gateway Routing Purge and Background Processor Verifier VistARad Clinical Display, Capture and TeleReader Management Utilities (MAG Enterprise, ET Phone Home) Architecture evolved over time as need occurred Built with C++, Delphi and M VistA Imaging is very large and complicated Import API Importer Storage management Architecture evolved over time as need occurred Built with C++, Delphi and M VistA Imaging is very large and complicated Import API Importer Storage management

3. 3 As Is Architecture Several clients all doing similar tasks Business logic in server and client Functionality not encapsulated Difficult to reuse existing functionality Each application creates own access to data (many RPC calls) Proprietary Storage Very functional system providing access to over 1.4 billion images

4. As Is Architecture Clients require intimate knowledge of internal systems Difficult to add new functionality (particularly to multiple clients) Functionality duplicated Several clients do the same job (display images, generate abstracts, store images) Business logic sometimes in client, sometimes in server Multiple clients doing image acquisition, all a little differently If the internal structure of the database had to be changed, it would require changing all of the clients as well (several thousand at most sites) Difficult to implement and change security Small functional changes require changes to multiple componentsMultiple clients doing image acquisition, all a little differently If the internal structure of the database had to be changed, it would require changing all of the clients as well (several thousand at most sites) Difficult to implement and change security Small functional changes require changes to multiple components

5. 5 As Is Architecture Business functionality not consistently applied Clients do same tasks differently Functional redundancy in Remote Procedure Calls (similar but inconsistent) Difficult to share data with other groups/enterprises Some clients import images in one way, others in another waySome clients import images in one way, others in another way

6. As Is Architecture Logical View