文档介绍：working: A Top Down Approach
junliangma@
4th edition. Jim Kurose, Keith Ross
1
2: Application Layer
Chapter 2: Application layer
Principles work applications
Web and HTTP
FTP
Electronic Mail
SMTP, POP3, IMAP
DNS
P2P Applications
Socket programming with TCP
Socket programming with UDP
2
2: Application Layer
Chapter 2: Application Layer
Our goals:
conceptual, implementation aspects work application protocols
transport-layer service models
client-server paradigm
peer-to-peer paradigm
learn about protocols by examining popular application-level protocols
HTTP
FTP
SMTP / POP3 / IMAP
DNS
work applications
socket API
3
2: Application Layer
work apps
e-mail
web
instant messaging
remote login
P2P file sharing
multi-work games
streaming stored video clips
voice over IP
real-time video conferencing
puting (网格计算)
4
2: Application Layer
Creating work app
write programs that
run on (different) end municate work
., web server municates with browser software
little software written for devices work work core devices do not run user applications
applications on end systems allows for rapid app development, propagation
application
work
data link
physical
application
work
data link
physical
application
work
data link
physical
5
2: Application Layer
Chapter 2: Application layer
Principles work applications
Web and HTTP
FTP
Electronic Mail
SMTP, POP3, IMAP
DNS
P2P file sharing
Socket programming with TCP
Socket programming with UDP
Building a Web server
6
2: Application Layer
Application architectures
Client-server
Peer-to-peer (P2P)
Hybrid of client-server and P2P
7
2: Application Layer
Client-server architecture
server:
always-on host
permanent IP address
server farms(服务器群) for scaling
clients:
communicate with server
may be intermittently(间歇地) connected
may have dynamic IP addresses
do municate directly with each other
client/server
8
2: Application Layer
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