ENG EC 441 Lecture Notes - Lecture 4: Gmail, Web Server, Telnet

• School: Boston University
• Department: Electrical & Computer Engineering
• Course: ENG EC 441
• Professor: Jeffrey Carruthers

Document Summary

Writing applications needs to run on multiple end systems. Do not need to write software that runs on network-core devices (routers and link-layer switches - not implemented in application layer) Confining application software to end systems has facilitated the rapid development and deployment of vast arrays of network app. Server is an always-on host which receives requests of objects from clients hosts and responds by sending the requested object to client host i. e. web: web server receives requests from browsers running on client hosts. The server has a fixed, well-known ip address. Facebook and twitter) employ one or more data centers. The service providers must pay recurring interconnection and bandwidth costs for sending data from their data centers. Minimal to no reliance on dedicated servers in data centers. Direct communication between pairs of intermittently connected hosts (desktops, laptops) called peers - don"t pass a server i. e. file sharing (bittorrent), internet telephony (skype) Cost effective - don"t require significant server infrastructure.