Facebook Friend Rank

This project does one thing: it attempts to rank a person's Facebook friend list from "best friend" to "worst friend".

It is a stand-alone ruby-based web service, built on top of Goliath, with the following goals:

• Deployable to heroku straight from the repository

• Requires only an access token and user ID (both found in the JS SDK FB.getAuthResponse() object), returns only a hash of IDs to scores to be used in your sorting algorithm

Try the quick demo app here to see some sample ranking results:

http://facebook-friend-rank.herokuapp.com/demo/index.html

Philosophy

It is impossible to absolutely rank your friends (let alone EVERYONE'S friends) without regard for context, cultural nuance, and ultimately the fidelity of an online persona with that of the real world.

This project attempts to do so anyways.

It may or may not provide a "reasonable" result anytime you need to rank a list of friends.

Ranking Strategy

Requires the read_stream permission.

Currently the ranking strategy is crude. It scans ~500 of a person's most recent feed items, tallies up the occurences of each unique friend ID, and returns this as the sorting data hash.

Ideally this evolves to into a adaptive solution which:

1. Determines which permissions are available and picks a strategy optimized for accuracy and speed-of-execution based on available data.

2. Offers biasing facilities, eg. to influence rank based on context or personal affinities defined by the calling app (this is a pipedream).

Usage

Once deployed (see deployment notes below) this web service has a single JSONP call of interest at the root URL.

http://facebook-friend-rank.herokuapp.com/?token=[fb-access-token]&id=[current-user-id]&async=[true/false]

Currently the access token requires the read_stream permission.

Because Friend Rank will take awhile to run, there are two modes of operation: asynchronous (progressive) and synchronous.

The returned hash may not contain entries for all friends, assume a zero value for these friends (they're the "worst").

The demo at /demo/index.html shows some simple usage of the ranking API. The key is that the endpoint does not and generally cannot immediately return a result. Rather it is refined with further processing, and all intermediate values are cached for ultra-fast lookups.

Asynchronous Usage (Default)

When the JSONP is made, Friend Rank returns immediately with an nearly empty hash. This initial call triggers the long-running ranking algorithm to start running in the background.

{
  "data":     {},
  "progress": 0.0
}

As it runs it builds up progressively more accurate and comprehensive results, which are found at the same endpoint. So subsequent calls will see more ranking data to work with:

{
  "data":     {"123451":9,"123452":99,"123453":1,"123454":1,"123455":1,"123456":1,"123457":1,"123458":2,"123459":2},
  "progress": 0.2
}

When "progress" reaches 1.0, the background process is complete.

The caller of this endpoint may choose to act on the friend rank data at any point, for example to sort friends early on in the process, or wait until the algorithm is complete before doing anything. Frankly speaking, Friend Rank is a heuristic which attempts to improve accuracy with more computation. Early results should have reasonable fidelity to those determined by a full run of the ranking algorithm.

This endpoint is fast, so it may be polled frequently.

Results are cached for an hour.

Synchronous Usage

By setting async=false in the call, you're instructing Friend Rank to return only when it is finished computing results in their entirety.

Note: an application which mixes asynchronous and synchronous calls may exhibit funny behaviour as a common cache is used.

Development

Run the development server on your machine by:

$ bundle install
$ foreman start

Note: Goliath requires a restart each time its files are changed.

Be sure to add a /etc/hosts entry mapping dev.facebook-friend-rank.herokuapp.com to 127.0.0.1 in order to be able to login using the bundled Facebook App ID. Then visit the demo app on your dev machine here:

http://dev.facebook-friend-rank.herokuapp.com:5000/demo/index.html

How To Deploy To Heroku

The following assumes you have a Heroku account in good standing, and have configured your development environment.

This repository is configured to use Memcachier out of the box. Cacheless/alternative cache deployments are not supported yet (fork me!).

$ git clone git@github.com:mikejarema/facebook-friend-rank; cd facebook-friend-rank
$ heroku apps:create --stack cedar --addons memcachier:25
$ git push heroku master

You can immediately play with the demo FB app at /demo/index.html and make calls to the JSONP endpoint (see usage notes above).

How To Deploy Elsewhere

You're on your own here (fork me!).

Roadmap

• Ensure all friends have a score in returned results

• Error handling

• Specs

• Different ranking strategies based on varying levels of permissions provided by the access token

Acknowledgements

• Thanks to Ilya Grigorik and his original team at Postrank for their phenomenal contributions to the Ruby & Event Machine open source communities, particularly Goliath and EM::Synchrony.

• Additional thanks to Ilya for his post: 0-60: Deploying Goliath on Heroku Cedar

• Thanks to Jeremy Keeshin for his post and bookmarklet: Who Does Facebook Think You Are Searching For?

• Thanks to Martyn Loughran for his post: An introduction to eventmachine, and how to avoid callback spaghetti

• Thanks to Mario Zelaya of Majestic Media for his insights on friendship strength and the Graph API

License & Notes

The MIT License - Copyright (c) 2012 Mike Jarema