[Xastir-dev] Re: [Xastir] Question/suggestion

[Gerry Wheeler KG4NBB]

On Wed, 2002-08-14 at 11:24, Ken Koster wrote:
> I've added the developers list to this as well since the topic is more
> appropriate there.

You're right. I should have thought of that.

> > 1) A mapping program that knows how to display a map, icons, bitmaps,
> > lines, polygons, filled areas, etc.
> 
> Or more likely it gives orders like 'give me "this" map from "that" database' 
> and is given triggers like "Hey, the aprs tnc receive program just received 
> a new map position for n7ipb-2" that it then acts on.
> 
> An APRS program that receives the data and stores it in an SQL database then 
> sends a trigger to sockets registered by other programs.  The trigger would 
> indicate such things as 'I just received a position for kg4nbb-2" or "I have
> a message for kg4nbb" or "a WX alert has just been stored".


 
> You've got it backwards, the drawing program should be asking for the data
> it needs, not being told what to do.  That way the problem of display goes
> away since presumably the display program will only ask for what it can
> use.   It asks for maps, and objects to display.  It accepts triggers that 
> it then is free to either use or ignore.

Well, perhaps, but I wouldn't want the drawing program to have to
understand the details of GPS, APRS, weather, or anything else. I was
thinking of it as being a blackboard upon which things get drawn. It
doesn't know what they are, beyond being icons, bitmaps, lines, etc. I
think the drawing program should be useable well outside the realm of
ARPS, GPS, etc.

I could see a trigger being something like "move previous icon xyz to
new position lat/lon". I wouldn't want them to be as specific as
"weather alert", or things like that. The APRS TNC (to follow your
example) should be, I think, the only one that understands APRS-specific
stuff. It should then translate the info into generic map-drawing stuff
for the drawing program.
-- 
Gerry Wheeler KG4NBB
kg4nbb at arrl.net
N26.28318  W081.75755