|(See the version of the diagram at the webinar for a larger image.)|
This first webinar focused on a new diagram depicting the layers of VISTA's architecture. This is a great grand-child of Tom Munnecke and George Timson's original Onion Diagram, which they drew on a napkin back in 1978 when they were first planning VISTA's architecture.
Where later onion diagrams developed by VA have increasingly emphasized VISTA's architecture as being constructed of plug-in packages, Tom and George's original diagram was trying to capture the idea of a health-information space, in which a small set of carefully thought out initial conditions would provide all the organization necessary for large numbers of autonomous developers working on their own could nevertheless create a coherent organic architecture. This is the same model used to build the Internet, and it is just about the opposite of the command-and-control model VA had been using up until then to try to do software development.
As VA later slipped increasingly back into the centralized authority model, then lost sight of the organic-growth model of design and reverted to trying to pre-specify the content of the system. This specification-driven model is what VA has been trying and fail to do for the last fifteen years without notable success, and it's what they're still trying to do in the new round of VISTA replacement projects (which try to part out the development of replacement VISTA packages (for their new iEHR initiative). This model cannot work because it is incapable of organizing such a complex system full of so many unknowns. It's what all this discussion of organic growth on this blog is about, that you cannot constrain reality at these scales without overreaching. Instead, you have to forward-bind your system, to leave room for future innovation and growth that you cannot presently foresee - in fact that most of your future development is going to be things you cannot foresee organized in ways you cannot foresee. Trying to plan all this out at the beginning - when we know as little as possible about how it eventually needs to look for it all to work - is building failure into the process from the outset.
The later generations of the Onion Diagram reflect this misunderstanding of Tom and George's original ideas, paying scant heed if any to the idea of an organically evolving health-information space in favor of a Legos approach to snapping together packages.
This webinar with its new Onion Diagram tries to remedy that situation by at least presenting the alternative viewpoint that the true architecture of VISTA is not package-based, that packages are just an organizational trick we use to divide up the work, that the true architecture of VISTA arises from plug-ins into dozens of extensible frameworks and the engines that run them, all of which is built upon a Von Neumann database-management system that allows the creation of an arbitrarily growing, arbitrarily interconnected network of integrated files and routines, which in turn is built upon a simple portability and integration layer.
I welcome your feedback about this new (or perhaps I should say return to the old) Onion Diagram. I'm hoping that in the comments section below the webinar, we can explore these ideas together.
The webinar is here: https://www.vxvista.org/display/vx4Learn/Introduction+to+VISTA+Architecture