Introduction Distributed System

Introduction Part 1 .. (English edition)

Definition of ... :

• Coulouris, et al  :  communicate and coordinate their actions only by passing messages.
• Andrew Tanenbaum : A collection of independent computers that appear to the users as a single coherent system, autonomous computers connected by a network, software specifically designed to provide an integrated computing facility.
• Leslie Lamport : You know you have a distributed system when the crash of a computer you’ve never heard of stops you from getting any work done. 

A broader definition : 

• A collection of processors executing independent instruction streams that communicate and synchronize their actions.
• Communication may be done via messages or shared memory.
• Includes multi-process and multithreaded programs running on a monolithic multiprocessor hardware

Picture of distributed system :

1. The Internet

2. An Intranet 
• 
3. Mobile Device
• 

Examples of Distributed Systems : 

• Distributed Multimedia Systems (Teleconferencing and Distance learning )
• Cellular phone systems
• IP Telephony
• Flight management system in an aircraft
• Automotive control systems (50+ embedded processors in a Mercedes S-class)
• Distributed file systems (NFS, Samba)
• P2P file sharing
• The World Wide Web