[Xastir] Annoucement: Serverbased user changeable filters (fwd)

[Curt Mills, WE7U]

Here's the original message.  Now you know how to play with it.

-- 
Curt Mills, WE7U                    hacker_NO_SPAM_ at tc.fluke.com
Senior Methods Engineer/SysAdmin
"Lotto:    A tax on people who are bad at math!"
"Windows:  Microsoft's tax on computer illiterates!" -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"

---------- Forwarded message ----------
Date: Sat, 11 Jan 2003 10:32:23 +0100
From: Roger Bille <roger.bille at telia.com>
To: TAPR APRS Special Interest Group <aprssig at lists.tapr.org>
Subject: [aprssig] Annoucement: Serverbased user changeable filters


 Dear all,

 Introduction:
 The APRS-IS full feed today have a lot of traffic and require a high
bandwidth, in particular for the APRS-IS server sites, but also for some of
you that connect that are only interested in the particular traffic. To
accommodate this a number of servers have special regional feeds which
filter the traffic. There are also some weather specific feeds available.
But all these are setup according to what the server operator "thinks" will
be good for the users. Now we can take this one step further.

 Now will each of you be able to select what traffic you are interested in
and the server will create a unique feed for you. There is great flexibility
to construct your personal feed.


 How does it work?
 Pete Loveall AE5PL have written the APRS-IS server software javAPRSSrvr in
java which is used by a number of servers. Pete has been kind to create some
hooks into his server software so I have been able to write a filter add-on,
javAPRSFilter (also in java). These 2 applications work together to provide
this filtering. Status on the APRS-IS servers can be found here:
http://ahubswe.net/aprs_stat.asp

 You define the filter by doing the following:

	1. Connect and logon to a filter enabled port on a server
	2. Send an APRS message to the server requesting the filter you want


 Filter commands
 There are 4 different kinds of filters that can be used in any combination.
Each filter is working independent and is additive to the feed. This mean if
the filter finds a match it will be passed to you. The filter commands in
the APRS message to the servers call is starting with the word 'filter'
(without quotes) and each filter command is delimited by a single space. A
message with just 'filter?' (without quotes) will return the current filter
definition.


 #1 Range filter
 The range filter will pass all stations and their beacons, status, messages
etc within a distance from a set location. It will also pass messages to
stations within the filter and positions of the message sender even if they
are outside the range. Up to 3 range filters can be used at the same time to
extend the areas when you have problem to find a good circle match.

 Syntax:	r/lat/lon/dist [r/lat1/lon2/dist2 [[r/lat2/lon2/dist2]]

 Where:	r = range command
		lat = latitude in degrees (no decimals). Negative for south
		lon = longitude in degrees (no decimals). Negative for west
		dist = distance in kilometers from lat/lon.
			I'm sorry we don't use miles here in Sweden ;-)

 Samples:	r/55/-4/600		This will pass all traffic for UK
		r/37/-81/1500	This will pass all east cost US traffic


 #2 Prefix filter
 The prefix filter will pass traffic based on if the sender’s call starts
with a specific pattern. Up to 10 patterns can be defined at the same time.

 Syntax:	p/p1/p2/p3... (up to 10)

 Where:	p = prefix command
		p# = The prefix (starting) pattern

 Samples:	p/K		This will pass all traffic from stations starting with K
		p/SK/F	This will pass stations starting with either SK or F
		p/SM5NRK	This will pass all traffic from SM5NRK and any SSID at the end


 #3 Budlist filter
 The budlist filter will pass traffic based on exact match of the sender’s
call. Also the SSID is part of the exact match. If you want all SSID use
prefix filter above. Up to 10 calls can be defined at the same time (if they
can fit in a single APRS message).

 Syntax:	b/call1/call2/call3... (up to 10)

 Where:	b = budlist command
		call# = The prefix (starting) pattern

 Samples:	b/SM5NRK		This will pass all traffic from SM5NRK without any SSID
		b/SM5NRK-5/SK5UM	This will pass all traffic from SM5NRK-5 and SK5UM


 #4 Type filter
 The type filter will pass traffic depending on the packet type. More than
one type can be defined in one single command.

 Syntax:	t/type

 Where:	t = type command
		type = is one or more of the following letters
			p = Position packets
			o = Objects
			i = Items
			m = Message
			n = NWS Weather
			w = Weather
			t = Telemetry
			q = Query
			s = Status
			u = User-defined

 Samples:	t/p		This will pass all traffic with a position
		t/w		This will pass all weather traffic. For positionless
				weather objects the corresponding position packet
				will also be sent when it is next heard
		t/mos		This will pass all messages, objects and status traffic


 Remeber that the APRS message must start with the word filter and the the
commands.

 The above filters can be combined as explain above. Each filter will
however working independent of the others, for example:

	filter r/63/16/1000 r/55/-4/600 p/F b/AE5PL t/s

 The above filter will pass all traffic within Nordic (range#1) AND UK
(range#2) AND stations starting with F (prefix) AND from AE5PL (budlist) AND
all status traffic (type).


 Where to connect?
 This is up to each server operator if/when they will provide this type of
service. The following servers and ports have this enabled as far as I know.

	ahubswe.net:14580
	aprsca.net:14580
	aprseast.net:14580
	aprswest.net:14580


 I welcome any comments, suggestions and complains. I monitor the UI-View
and APRSSIG lists.

 73 and have fun
 Roger Bille/SM5NRK