3-MAY-2019: In order to be compatible with new ADS-B Exchange API access policy abds_hub was updated to version 2.9 It requires slightly different configuration: new value of host parameter and new key parameter. Please check details in example below.
As a largest source of unfiltered flight data ADS-B Exchange allows to explore an air traffic around the world. Starting with adsb_hub 2.3 it's possible to consume ADS-B Exchange feed using RealADSB iOS app.
Main reason to do that is to minimize amount of data sent to mobile device, reducing associated expenses and keeping battery alive much longer. For example one snapshot of air traffic data around busy airport can be as much as 170Kb, adsb_hub will filter out unnecessary information cutting it to 50Kb and with compression just 10Kb will be actually transmitted to iPhone/iPad. However for your local area, since data coming from 3rd party web site with delays, it's not a replacement for good antenna and ADS-B receiver. Also this functionality is ONLY intended for personal learning or/and entertainment. When adsb_exchange input is in use you shouldn't expose adsb_hub ports to the Internet.
adsb_hub can be started with command line java -jar adsb_hub.jar exchange.json > 1.log &
adsb_exchange - calls ADS-B Exchange to get latest traffic in area specified by following parameters: latitude, longitude, radius in miles.
key value for access to API can be requested here.
interval in seconds is used to specify how often get updated traffic data from ADS-B Exchange, default is 10 seconds and value can't be less than 3 secnonds.
mlat_color parameter can be used to override default color of MLAT traffic in RealADSB iOS app, format is #RRGGBB.
bonjour - exposes TCP/IP port used by RealADSB iOS app.