TagPulse is a Twitter-like distributed Micro-blogging web service in JAVA. A new Httpserver or a Data Server can be added at any time and is configured by providing the IP address of one of the existing servers. I distributed the data servers using LAZY replication, the servers are synchronized by GOSSIPING mechanism using JSON. The system can handle n-1 failures and provides causal ordering of tweets using VECTOR clocks like Amazon's DYNAMO. I also implemented CACHING on the Http server to reduce bandwidth overhead. I used Unix SHELL scripts to launch and deploy all the servers automatically in different machines. Please feel free to check out my blog on Lazy Replication. http://satheesh7.blogspot.com/2010/12/lazy-replication.html

TagPulse service provides RESTful APIs for,

-Users to POST tweet.(Pulse it)
-SEARCH for tweets(pulses) based on Hash Tags.
-Users can DELETE their pulses.
-Users can RE-PULSE other user's posts.
-FOLLOW other users.(Users get the time-lines of other users when they start following others)

Also implemented gossiping, log table pruning, delete mechanism and handled failures robustly in the distributed environment. Like twitter you can follow other users, have user profiles and re-tweet.

I also used this opportunity to learn and develop an ANDROID application for TagPulse using these APIs. I implemented OAUTH mechanism for secure authentication. I have uploaded a demo video of TagPulse, please use full screen 720p to watch it in HD.

http://www.youtube.com/watch?feature=player_embedded&v=l2RmMFUrsLU

Source files are available at,

https://github.com/sathify/tagpulse/tree/master/backend/src
https://github.com/sathify/tagpulse/tree/master/android/src/tag/pulse