1. By: Asaf Oren & Gilad Eisenberger Supervisor: Ittay Eyal Spring 2009 Networked Software Lab

2.  Enable PTT communications between users without a central service  Create implementation that works over the internet  Use reasonable amounts of bandwidth  Learn  Have fun

3.  A method of communicating  One user can talk at a time  Press button to start talking  Release button when finished

4.  Available everywhere  Not reliable  IP Based  Great model for private (and public) networks  Accessible to us  This is what we base our assumptions on

5.  Application, distributed  Joining, leaving  Request floor, release floor  User interface

6.  C#,.Net, Visual Studio  UDP Networking  WinAPI for sound  Serialization  Low-level network protocol  Single threaded

7. Sends message objects User addressing (send to a user, not an address) High Level Protocol Reliable/non-reliable In-Order Connection aware Low Level Protocol No corruption Connectionless UDP

8.  Originally – 3 phases ◦ Server-Client ◦ Mixed mode ◦ Distributed  Actually – only 2 phases ◦ Dropped mixed mode

9.  Two different applications  Similar general design  Asymmetric protocol

11.  Server->Client ◦ Add, Remove User ◦ Floor Response, Changed ◦ Sound (not reliable)  Client->Server ◦ Connect, Disconnect ◦ Floor Request, Released ◦ Sound (not reliable)

12.  Symmetry  Tree topology ◦ Changes in user management  Protocol changes ◦ Remove Floor Changed message ◦ Changes in User messages

14.  Works! (demo at end)  Great proof-of-concept  Meets requirements  Many problems solved  Few problems left open ◦ NAT, Reconnections, Security

15.  Can be adapted to commercial product  Can add new features (not part of original problem) ◦ Text messaging ◦ Private talks

17.  (and hopefully answers)