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…...