Chapter 2:Application layer r 2.1 Principles of r 2.6 P2P file sharing network applications r 2.7 Socket programming r 2.2 Web and HTTP with TCP r 2.3 FTP r 2.8 Socket programming r 2.4 Electronic Mail with UDP SMTP,POP3,IMAP r 2.9 Building a Web r 2.5 DNS server 2:Application Layer 6
2: Application Layer 6 Chapter 2: Application layer r 2.1 Principles of network applications r 2.2 Web and HTTP r 2.3 FTP r 2.4 Electronic Mail v SMTP, POP3, IMAP r 2.5 DNS r 2.6 P2P file sharing r 2.7 Socket programming with TCP r 2.8 Socket programming with UDP r 2.9 Building a Web server
Application architectures r Client-server r Peer-to-peer (P2P) r Hybrid of client-server and P2P 2:Application Layer 7
2: Application Layer 7 Application architectures r Client-server r Peer-to-peer (P2P) r Hybrid of client-server and P2P
Client-server architecture server: ÷always-on host permanent IP address server farms for scaling clients: communicate with server may be intermittently connected may have dynamic IP addresses do not communicate directly with each other 2:Application Layer 8
2: Application Layer 8 Client-server architecture server: v always-on host v permanent IP address v server farms for scaling clients: v communicate with server v may be intermittently connected v may have dynamic IP addresses v do not communicate directly with each other
Pure P2P architecture r no always-on server r arbitrary end systems directly communicate r I peers are intermittently connected and change IP addresses r example:Gnutella Highly scalable but difficult to manage 2:Application Layer 9
2: Application Layer 9 Pure P2P architecture r no always-on server r arbitrary end systems directly communicate r peers are intermittently connected and change IP addresses r example: Gnutella Highly scalable but difficult to manage
Hybrid of client-server and P2P Skype Internet telephony app Finding address of remote party:centralized server(s) Client-client connection is direct(not through server) Instant messaging Chatting between two users is P2P Presence detection/location centralized: User registers its IP address with central server when it comes online User contacts central server to find IP addresses of buddies 2:Application Layer 10
2: Application Layer 10 Hybrid of client-server and P2P Skype v Internet telephony app v Finding address of remote party: centralized server(s) v Client-client connection is direct (not through server) Instant messaging v Chatting between two users is P2P v Presence detection/location centralized: • User registers its IP address with central server when it comes online • User contacts central server to find IP addresses of buddies