The Start Shawn Fanning (19-yr-old student nicknamed Napster) developed the original Napster application and service in January 1999 while a freshman at Northeastern University –Share MP3 files with peers around the world Next version: launched in May 1999, by Shawn Fanning (19-yr- old student nicknamed Napster) and Sean Parker (20) Allowed Users to MP3 Files - compression format, good quality but 1/12 th original size –Napster.com: p2p MP3 exchange service November 2000 – Napster has 38 Million members 40 million users in first 18 months At peak,70 million users 1.57 million simultaneous users

Client-Server File Sharing Server(s) perform all file sharing tasks –All files stored on server(s) –All queries regarding file availability addressed by server(s) –All files transmitted from server(s) Therefore, server(s) constrain performance –Can only hold as many files fit in server storage –Query response time dictated by server speed –Files transmitted over server network connection with limited capacity

Peer-to-Peer File Sharing At least some tasks are distributed among peers: –Files stored on and transmitted from peer hosts –Queries regarding file availability addressed by peer hosts Distributed tasks are not limited by server performance –Network can hold as much as can be stored on all peers –Transmission costs shared by all peers –Each peer contributes to responding to queries For example, –Napster distributed file storage and transmission –File availability was centralized

Concept of Napster Napster used centralized servers to keep a catalog of available files 1. User sends out request Napster searches central database Search request 2. The central server sends back a list of available files for download Search response Napster server user 3. Requesting user downloads the file directly from another Napster user computer Download from user

napster.com users File list is uploaded 1. A Simple Example

napster.com user Request and results User requests search at server. 2. A Simple Example

napster.com user pings User pings hosts that apparently have data. Looks for best transfer rate. 3. A Simple Example

napster.com user Retrieves file User retrieves file 4.

Advantages and Disadvantages of Centralized Indexing Advantages: –Locates files quickly and efficiently (more effective) –Searches are as comprehensive as possible –All users must registered to be on the network Access is controlled Disadvantages: –Vulnerable to censorship and technical failure System has single points of entry; one fails could bring whole system down –Popular data become less accessible because of the load of the requests on a central server –Central index might be out of data because the central server’s database is only refreshed periodically Resource Discovery

Screenshots – Napster Searching …

Screenshots – Napster Downloading ….

Traffic Generated by Napster 3/00: 25% UWisc traffic Napster 2000: est. 60M users 7/01: # simultaneous online users: Napster 160K Gnutella: 40K Morpheus: 300K Approximately 10,000 music files were shared per second using Napster, and every second more than 100 users attempted to connect to the system and there will be 75 million Napster users by the end of 2000

Reported Bandwidth of Napster

End of Napster 12/99: first lawsuit April 2000 – Metallica starts law suit – Huge and long court case July 2001 – Napster ordered offline, June 2002 bankrupt 2/01: US Circuit Court of Appeals: Napster knew users violating copyright laws After the Recording Industry Association of America sued Napster for copyright infringements, the court ruled that Napster was indeed violating copyrights and it is shut down Napster argued since it was only involved in collecting the information about files available, it was legal; Napster never shared any illegal file. The courts thought otherwise. Napster network died without a central machine.