PPT: Application Layer | Computer Networks - Computer Science Engineering (CSE) PDF Download

 Page 1


Application Layer
slides are modified from J. Kurose & K. Ross
Page 2


Application Layer
slides are modified from J. Kurose & K. Ross
2: Application Layer 2
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 applications
r 2.7 Socket programming with TCP
r 2.8 Socket programming with UDP
Page 3


Application Layer
slides are modified from J. Kurose & K. Ross
2: Application Layer 2
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 applications
r 2.7 Socket programming with TCP
r 2.8 Socket programming with UDP
2: Application Layer 3
Processes communicating
Process:
program running within a host
Client process:
initiates communication
Server process:
waits to be contacted
process sends/receives messages to/from its socket
identifier includes both IP address and port numbers
associated with process on host.
process
TCP with
buffers,
variables
socket
host or
server
process
TCP with
buffers,
variables
socket
host or
server
Internet
Controlled by OS
controlled by
app developer
Page 4


Application Layer
slides are modified from J. Kurose & K. Ross
2: Application Layer 2
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 applications
r 2.7 Socket programming with TCP
r 2.8 Socket programming with UDP
2: Application Layer 3
Processes communicating
Process:
program running within a host
Client process:
initiates communication
Server process:
waits to be contacted
process sends/receives messages to/from its socket
identifier includes both IP address and port numbers
associated with process on host.
process
TCP with
buffers,
variables
socket
host or
server
process
TCP with
buffers,
variables
socket
host or
server
Internet
Controlled by OS
controlled by
app developer
2: Application Layer 4
App-layer protocol defines
r Types of messages exchanged,
v e.g., request, response
r Message syntax:
v what fields in messages & how fields are delineated
r Message semantics
v meaning of information in fields
r Rules for when and how processes send & respond to
messages
Public-domain protocols: Proprietary protocols:
¨ defined in RFCs ¨ e.g., Skype
¨ allows for interoperability
¨ e.g., HTTP, SMTP
Page 5


Application Layer
slides are modified from J. Kurose & K. Ross
2: Application Layer 2
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 applications
r 2.7 Socket programming with TCP
r 2.8 Socket programming with UDP
2: Application Layer 3
Processes communicating
Process:
program running within a host
Client process:
initiates communication
Server process:
waits to be contacted
process sends/receives messages to/from its socket
identifier includes both IP address and port numbers
associated with process on host.
process
TCP with
buffers,
variables
socket
host or
server
process
TCP with
buffers,
variables
socket
host or
server
Internet
Controlled by OS
controlled by
app developer
2: Application Layer 4
App-layer protocol defines
r Types of messages exchanged,
v e.g., request, response
r Message syntax:
v what fields in messages & how fields are delineated
r Message semantics
v meaning of information in fields
r Rules for when and how processes send & respond to
messages
Public-domain protocols: Proprietary protocols:
¨ defined in RFCs ¨ e.g., Skype
¨ allows for interoperability
¨ e.g., HTTP, SMTP
2: Application Layer 5
Transport service requirements of common apps
Application
file transfer
e-mail
Web documents
real-time audio/video
stored audio/video
interactive games
instant messaging
Data loss
no loss
no loss
no loss
loss-tolerant
loss-tolerant
loss-tolerant
no loss
Throughput
elastic
elastic
elastic
audio: 5kbps-1Mbps
video:10kbps-5Mbps
same as above
few kbps up
elastic
Time Sensitive
no
no
no
yes, 100’s msec
yes, few secs
yes, 100’s msec
yes and no