Federated Location Sharing

Goals

• Share different types of location (point, venue, city) with different people
• Syndicate location from your own site to services like Foursquare, Gowalla, etc

Notes

GeoRSS and GeoJSON already exist – this already exists in RSS and JSON

Problem: in GeoJSON you can't represent a circle...

• GeoJSON http://geojson.org/
• GeoRSS http://georss.org/Main_Page
• ARML – http://openarml.org/
• KML

Two people want to be notified if they are within a certain distance of eachother – but they are on different servers... How can you do a comparison on proximity without giving away exact position?

Series of yes/no questions? Very chatty.

Like the "millionaires' problem" (see also Secure multi-party computation). You can compare two numbers without giving away the actual values... you can do this to lat/long pairs as well...

Blur fliter -

Tantek: “I want to check in from my own site.”

Fireeagle defined levels of fuzziness...

Brightkite – allowed you to “check in” and then blur your location out...

How do you de-centralize four-square. - Tantek has implemented de-centralized twitter... push from there to foursquare, to brightkite, to gowalla... Use microformats... “the database on the web” - use Yahoo! Searchmonkey “show me all the hcards that have this location”... You need realtime aggregator – to store check-ins, to share check-ins...

What's the open format for this? Should be an activity stream with a special verb...

Cache but don't copy venue data from other places...

It might take more than one URI to describe a place – how do you tell that...

Geoloqi's Approach

(geoloqi.org) - slides

• Layers are a collection of places of interest
• Users can create their own layers (i.e. of favorite places)
• Users can subscribe to public channels (i.e. a list of all US cities)
• Actions can be set per layer, i.e.
  • Update my AIM status whenever I am in a location on the "City" layer
  • Send my carpool buddies an SMS when I'm 1/2 mile from the pickup spot
  • Check in to FourSquare when I'm in a location on my "Restaurants" layer
  • [Your action here] - run this callback URL whenever I enter a place in the "secret locations" layer
• Places of interest generated a trigger when:
  • When entering the place
  • When leaving the place
  • After being at this place for n minutes
  • If not in the place at the specified time interval

Outcomes

• Layer is a collection of "places of interest".... Every user can define their own layers based on landmarks relevant to them...
• Could be a shape (GeoJSON), could be a point (lat/long/radius)
• Privacy is set per layer, not per person
• People can set up their own layers. "this is home, this is work, etc..."
• Places are also defined by time and date - E.g. Glastonbury
• Some places of interest move around – e.g. your car...

People

Aaron Parecki, Don Park, Tantek Çelik, Daniel Appelquist, Tuomas Koski