At 03:00 PM 5/18/00 -0400, Doug Chamberlin wrote:

>
>Let's say I have an application which lists a subset of records from a
>table in a visible window. The record set is obtained via a query with a
>WHERE clause. That application would like to know when any of those records
>are updated in the database so that it can update its window. If any of the
>records has been updated, the application would ideally like to re-issue
>the same query which populated the window.
>

I would have the update trigger post something like "Employee:" | empl_id
for employees, for example. The program would construct an event
block containing like entries for all displayed records (there is
a problem if event block exceeds 32K? 64K?). When it received
notification it would find the event names with different event
counts, strip off "Employee:" and be left with the primary key to
refetch the record.

I must say that figuring this out from the current documentation
is next to impossible. As far as I can tell, the manuals never
quite got around to describing the format of the event block, which
is fairly significant. To be completely frank, the sections on
events are unfathomable to me even though I designed the feature
and wrote the code. The fact that people are having trouble figuring
them out is upsetting but, unfortunately, not surprising.

Around the time of V3, Dr. Depalma wrote a superb OSRI reference
manual. Rumaging around the attic recently we found a backup of
Don's full documentation directory, so maybe we could get the book
back in print. Anybody out there want to write a set of Nroff
macros to generate HTML? Many, many glory points here.

Jim Starkey