1. Lecture 17 Page 1 CS 188,Winter 2015 A Design Problem in Distributed Systems CS 188 Distributed Systems March 10, 2015

2. Lecture 17 Page 2 CS 188,Winter 2015 The System A massive Internet game –A multiplayer fantasy game Intended for millions of users worldwide Real time interactions between players Player actions create permanent changes in the game world

3. Lecture 17 Page 3 CS 188,Winter 2015 Some System Characteristics High degree of interaction between players Intended for real time use –Ideally, everything seen by everyone instantly Requires storing and accessing multiple megabytes per user

4. Lecture 17 Page 4 CS 188,Winter 2015 The Business Model Play is free for everyone Sell premium “stuff” –Game items giving players advantages Maybe toss in a little advertising revenue

5. Lecture 17 Page 5 CS 188,Winter 2015 What Are The Distributed Systems Problems? Performance Scale –In users, data, messages Consistency model Handling data Handling varying network characteristics Failures and recoveries Security issues

6. Lecture 17 Page 6 CS 188,Winter 2015 Performance What are the critical performance characteristics for this system? –Especially those related to distributed systems issues What will count as acceptable performance? What factors are likely to get in the way of that? How do we overcome those performance challenges?

7. Lecture 17 Page 7 CS 188,Winter 2015 Scale What are the actual scaling characteristics? What approach should we take to dealing with them? What technical challenges will be involved in that approach? What will we do to meet those challenges?

8. Lecture 17 Page 8 CS 188,Winter 2015 Consistency Model How much consistency will we provide in this system? Will we provide the same degree of consistency for all operations? What approach(s) will we take to achieving such consistency?

9. Lecture 17 Page 9 CS 188,Winter 2015 Handling Data What will be the fundamental characteristics of our storage system? How distributed will our storage be? Will we use replication? –If so, where, what form, for what data?

10. Lecture 17 Page 10 CS 188,Winter 2015 Handling Varying Network Characteristics How will we deal with temporary network failures? –To player machines? –To server machines? How will we deal with varying latencies? Will we require minimum network characteristics to participate? –If not, is there a fairness issue?

11. Lecture 17 Page 11 CS 188,Winter 2015 Failures and Recoveries What do we do when a player node fails? –And when it recovers? What do we do when a server node fails? –And when it recovers? Is partitioned operation allowed?

12. Lecture 17 Page 12 CS 188,Winter 2015 Security What are the security goals for this system? What are the security issues for this system? –Particularly those related to its distributed nature How will we achieve our goals?