Re: [Hardhats-members] Migrating vista console module routines to client side GUIs

[Gregory Woodhouse]

On May 2, 2006, at 3:28 AM, Jim Self wrote: I think you will find that the three cons you listed are very much the rule rather than the exception. Fileman roll-and-scroll applications resemble a conversation in some ways. They support a highly variable dialog of questions and answers that does not lend itself to simple minded screen scraping or superficial mapping to a GUI. I believe that there is very little hope of broad success in any approach to putting a GUI on VistA applications that does not develop with a deep connection to the metadata. It's worth pointing out that the Fileman DBS API (originally known as the "Silent Calls") is quite new, and does not represent a new front end to the same code. In fact, if you do a lookup with FIND^DIC or LIST^DIC you do NOT end up calling the same code that you would have if you used a Classic call like ^DIC or IX^DIC. The DBS APIs are, in many  ways, a complete rewrite, and they were introduced at the same time as the RPC Broker, the use of Delphi and CPRS in order to support developing GUI applications under VistA. Such a project was not undertaken lightly, and Jim is absolutely right about the difficulty of using simple approaches like screen scraping to implement GUIs. I'm not saying that it's impossible, but certainly, when CPRS was introduced it was felt that a rewrite of the infrastructure (essentially from the ground up) was needed, and that's precisely what happened. Jim is also right on target with the issue of metadata. Rather than abstracting away from the underlying implementation, VistA has typically dealt with metadata (and what are sometimes loosely referred to as "business rules") in MUMPS code, placing an even greater burden on those who want to develop new interfaces. Please note that I am NOT saying this shouldn't be done! What I AM saying is that there are good reasons to think that a complete rewrite of portions of VistA may be the more realistic way to achieve that goal. Gregory Woodhouse [EMAIL PROTECTED] "Those who are enamored of practice without theory are like a pilot who goes into a ship without rudder or compass." --Leonardo da Vinci (1452-1519)