Accessor: services/RedPinLocation

This accessor obtains the location corresponding to a WiFi fingerprint from a RedPin localalization server http://redpin.org/. The RedPin server must first be configured with a map and trained with (fingerprint, location) matchings before it can be used with this accessor. For now, the easiest way to accomplish this is by walking around and tagging locations with the RedPin Android app available at https://github.com/MaKeAppDev/Redpin. Unfortunately, the iPhone app has difficulty obtaining fingerprint values from the phone.

This accessor is triggered by an input to the wifiReadings input, at which time a getLocation action is sent to the RedPin server over a raw TCP socket with specified host URL and port. These values default to those for the RedPin server running at "terra.eecs.berkeley.edu" on port 8090. Upon receiving a response from the server, the accessor parses out the "symbolicID" and "mapName" fields and outputs them on the location and MapName outputs respectively.

It appears the RedPin server doesn't validate its input and will return a location response to this accessor even if the wifiReadings array is ill formed. However, this accessor will raise an error if an element of the wifiReadings array is missing a field.

To obtain WiFi scan data on a mac, you can use the command line tool $/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -s

The format of the wifiReadings parameter is consistent with the RedPin interface specification at http://redpin.org/resources/docu/interface_spec.pdf for the "getLocation" action. E.g. [{ "ssid": "AirBears2", "bssid": "e8:65:49:e9:16:3b", "wepEnabled": false, "rssi": -88, "isInfrastructure": true }, {...} ]. This input triggers a raw TCP socket connection to the RedPin server running at host and port.