This is an application which displays the currently trending Meetup groups based on their (live) RSVPs feed. It's built using Java EE 7 (uses WebSocket client & server APIs, Singleton EJB timers and CDI events to wire things up) and Redis

From Meetup to Redis

• A WebSocket client consumes live Meetup RSVP feed
• It parses each RSVP pushes the groups related data to a Redis sorted set
• Uses Jedis client for Redis and Jackson for POJO based JSON binding

From Redis to trending Meetup groups

Once the data is in a Redis sorted set

• A Singleton EJB polls Redis to get top 10 (using Jedis#zrevrangeByScoreWithScores) groups as per data in the RSVPs
• The information is pushed to a WebSocket endpoint via CDI
• Redis sorted set does all the heavy-lifting: Java EE helps build the solution on top of all this
• The WebSocket endpoint is consumed from within a HTML file which is in turn accessed by the end user

To run

• clone
• start Redis instance
• change Redis connection details here and here
• mvn clean install
• deploy the WAR file in any Java EE 7 (or above) compliant container
• browse to http://<host:port>/meetup-trending/ e.g. http://localhost:8080/meetup-trending/

You should see something like this - Score represents the frequency of the group occurence in the RSVPs (popularity)

Credits

• Inspiration was obtained from here
• I am terrible at front end.. yes, even the most simplest ones. So I picked up things from here

TODOs

• CDI Producer for Jedis client
• find other TODOs