Computer Technology

In: Computers and Technology

Submitted By m7md11
Words 855
Pages 4
Computer
 Networks
 
Applica3on
 Layer
 

1

 

Examples
 of
 network
 applica3ons
 
• 
• 
• 
• 
• 
• 
• 

e-­‐mail
 
web
 
instant
 messaging
 
remote
 login
 
P2P
 file
 sharing
 
mul3-­‐user
 network
 games
 
streaming
 stored
 video
 clips
 

•  social
 networks
 
•  voice
 over
 IP
 
•  real-­‐3me
 video
 
conferencing
 
•  grid
 compu3ng
 

2

 

1

Crea3ng
 a
 network
 app
 
write
 programs
 that
 

application
transport
network
data link
physical

–  run
 on
 (different)
 end
 systems
 
–  communicate
 over
 network
 
–  e.g.,
 web
 server
 soJware
 
communicates
 with
 browser
 
soJware
 

No
 need
 to
 write
 soJware
 for
 
network-­‐core
 devices
 
–  Network-­‐core
 devices
 do
 not
 
run
 user
 applica3ons
 
 
–  applica3ons
 on
 end
 systems
 
 
allows
 for
 rapid
 app
 
development,
 propaga3on
 

application
transport
network
data link
physical

application
transport
network
data link
physical

3

 

Applica3on
 architectures
 
•  Client-­‐server
 
–  Including
 data
 centers
 /
 cloud
 compu3ng
 

•  Peer-­‐to-­‐peer
 (P2P)
 
•  Hybrid
 of
 client-­‐server
 and
 P2P
 

4

 

2

Client-­‐server
 architecture
 
server:
 
 
–  always-­‐on
 host
 
–  permanent
 IP
 address
 
–  server
 farms
 for
 scaling
 

clients:
 
client/server

–  communicate
 with
 server
 
–  may
 be
 intermiPently
 
connected
 
–  may
 have
 dynamic
 IP
 
addresses
 
–  do
 not
 communicate
 directly
 
with
 each
 other
 

5

 

Google
 Data
 Centers
 
•  Es3mated
 cost
 of
 data
 center:
 $600M
 
•  Google
 spent
 $2.4B
 in
 2007
 on
 new
 data
 centers
 
•  Each
 data
...