Architecture
                              
            (Introduction to Medical Informatics)
         (http://www.cpmc.columbia.edu/edu/textbook)

LAST REVIEWED:  10 October 1996

ARCHITECTURE

types (review from IAIMS)
     multiple terminals - put many terminals at each station
     workstation - terminal emulation can get to all applications
     interfacing - applications talk to each other
     redundant storage - central repository & common review
     integration - change logic and user interface to look
          like one application
     monolithic - rewrite applications in one system
     
     issues:
     +common user interface
     +ability to reuse data (aggregate disparate data)
     +ability to buy existing products (instead of writing them)
     -loss of performance
     -need to rewrite code
     -need to deveop interface standards and common vocabulary
     -cost (terminals, networks, applications, ...)

what has succeeded is workstation, interfacing +/- common
     storage, monolithic
     interfacing seems to be winning
     monolithic are being converted, new ones not being created
     workstation requires too much redundant entry of data
     (cannot exploit)

Arguments for an open, interfaced system, versus a monolithic one:
     (ie, what is the tradeoff)

(why not build a monolithic system)

-one group cannot develop all the applications needed in medicine
     (20 years for LDS and Beth Israel)

-important changes in technology occur in the time it takes
     to build a comprehensive system

-asking users to avoid new applications, hardware will lead
     to resentment and obsolescence

-vendors can spread the cost of development over many
     customers

-it is more expensive to build programs than to buy them,
     and maintenance makes up at least 50% of their total
     cost

(why not buy a monolithic system)

-no single vendor will offer all that is needed

-relying on a single vendor is risky

(therefore, interface and integrate)

-there is a move to empower departments, not control them
     centrally

- user interface standards allow vendors to coordinate their
     interfaces (Macintosh, X-Windows, Windows)

-network speeds will increase

-standards for interfacing are developing

-cannot enter duplicate data

(but keep this in mind)

-response time is critical, more than ease of use

-data entry must be easy, especially if benefits are
     indirect

-if there is value, they will use it regardless

related reading:
     Clayton PD, Sideli RV, Sengupta S. Open architecture
     and intergrated information at Columbia-Presbyterian
     Medical Center. M.D. Computing 1992;9(5):297-303.