[Flightgear-devel] New feature: METAR for multiple airports

[Torsten D. <To...@t3...>]

Hi, 

I just pushed a patch that provides functionality for more than one METAR in 
the property tree. This patch also provides the magnetic variation for the 
reporting station exposed to a property.

For backwards compatibility, the METAR for the nearest airport still live 
under /environment/metar. This report is pulled from NOAA on a regular 
schedule.

I have configured eight additional sets of METAR properties, they live under
/environment/metar[1]
..to..
/environment/metar[6]
/environment/metar[10]
/environment/metar[11]
each of them share the same behaviour: everytime, the associated property 
"time-to-live" is zero, a report for the station named in the property 
"station-id" is requested from NOAA, parsed and written to the corresponding 
properties for that station.

My idea is to have the /environment/metar indexes [1..6] to be used for ATIS 
weather. A system (still to be created) should check the currently selected 
radio frequencies, find the associated airport and write that airport id to 
it's corresponding "station-id", along with "set time-to-live" set to zero and 
"valid" set to false. The realwx system now schedules a http request, tries to 
parse the response, fills all properties and sets "valid" to true. The report 
will be reloaded every time, the property "time-to-live" gets zero. This 
property counts down automatically.
The metar indeces 10 and up are for "user-defined" weather systems, like the 
local-weather and can be used for lateral weather interpolation and alike.

All these modifications should not change the current behaviour of the live-
weather system. If it does, it's a bug!

I hope, this prepares the ground for a more realistic weather system and 
correct ATIS report for the tuned station. 

Happy new year, everybody!

Torsten