what is server

 

in this video we will study about web

server

and application server and this video

will hopefully clear some of your doubts

regarding web server and application

server

so let's begin what is a web server

web server is a computer system

that hosts websites so what do you mean

by websites

it's a collection of web pages

so for example when you open amazon.com

it's a website and it does not have a

single web page but it has multiple web

pages

so when you open it you see the home web

page

but when you click on a product you will

be uh

taken towards a different web page that

will be the product web page

and there you will see multiple things

the image of the product info

and even recommendations so that means

website and then any computer system can

be a web server

what is the difference between a normal

computer system

and a web server so the difference is

that

this computer system is running a web

server software

for example apache http

web server this is the most popular one

today as of now

then we have microsoft iis and some

others

so is this the only difference that

computer system

and a computer system running web server

software

no there is one more difference and the

second is that

this computer system should be connected

to internet

in order to act as a web server

otherwise

uh clients web clients cannot contact it

through http

so it may not be able to it will not be

able to serve those

so it will not be acting as a web server

so it should be connected to internet

and it should be running a web server

software

so uh typically web servers host

multiple websites

some only host a few while others may

host several hundreds

but there are some dedicated servers

also

so based on that we will categorize a

web server

into two parts one is that web servers

that host websites for multiple users

these are called shared hosts

and there are some dedicated uh web

servers that will be hosting uh

websites for single person or company

and these will be called

dedicated hosts

so which servers are shared and which

are dedicated

so when let's say there is some personal

website

or some small websites which

does not have huge amount of traffic

then those who

would be uh generally hosted on shared

hosts

but uh if there is a huge website and it

has

a high traffic then that requires

a dedicated server for that and also if

the sites require custom server

modification then it will go for

dedicated hosts now uh let's understand

how this web server works

so if we have a web server let's

say this is the web server then there

must be a client

client whom the server is serving so we

will call it

web client so this client

sends an http request to the web server

and it will request for some page or it

will require for some other resources

so there are two possibilities one

possibility is that the

requested url the page that is requested

or the file that is requested

is present with the web server then it

will immediately send

a http response with the file

but it may be possible that that is not

present on the web server

so it can look into a static

database so these are files that is

present to this

then there may be also static database

which the web server can contact and

fetch the file

and return to the send http response but

there may be scenario that

this is not present in the staticdb but

it needs some processing

then what this web server will do is

that it will

send a servlet request to the

application server so you can now see

application server coming into

picture it will send a

servlet request

to application server so just a quick

info what is a servlet if you may be

wondering a servlet is a small java

program that runs with a web server

servlets receive and respond to requests

from web clients usually across

http so these will be some java programs

so it will require some processing so it

will send this servlet request

to this application server it will

contact the

application data store

in order to process run this servlet and

fetch some

details from here and do further

processing

and then it will send a servlet response

to the web server and now this web

server has the

response built in so response ready so

it can

send http response back to the

web client so this is how web server

works

and this application server may not be

always required but it may be required

when some intense processing is required

which web server cannot handle so this

is a

rough idea and you should understand

this flow

now let's see some of the examples of

web servers so one

most popular web server is apache http

server

and its most popular as of now it's

developed by

apache software foundation

and just a rough estimate roughly 60

percent

of the web servers run apache web server

and it can be installed on

all operating systems including linux

unix windows

freebsd mac ox osx and more

and it's a open source software so all

of these

are related to its popularity that's why

it's so popular

then we have internet information

services or in sort iis

it's developed by microsoft

and it runs on windows nt 2000 and 2003

platforms

and it is tightly integrated with the

operating system

so it is easy to administer it then we

have some other web servers like lite pd

sun java system web server and jigsaw

server

there are a few more but those are not

that much popular

now we have a good understanding of web

server we also know

the most popular web servers how web

server functions

now let's quickly look at application

server

so application server is a server that

is specifically designed to

run applications and here also we had

seen that

this was coming into picture when this

web server did not had the request ready

and it needed to run some

java program to build the response

so it's a server designed for running

applications

and it includes both hardware and

software that

provide an environment for programs to

run

so what are some of the uses of

application server

it's used for running web applications

hosting a hypervisor that manages

virtual machines so what are hypervisors

these are software programs that manage

one or more virtual machines and these

can be used to create

start stop and reset virtual machines

then application server can be used for

distributing and monitoring software

updates and also processing data sent

from

another server now next question is why

we use application server we already

have some idea why we use application

server

so a web server if you see is designed

and often optimized

to serve web pages and not more than

that

therefore it may not have the resources

to run demanding web applications

so an application server provides the

processing power

and the memory to run these applications

in real time

it also provides the environment to run

specific applications

for example let's say a cloud service

may need to process a data

on a windows machine

and a linux based server may provide the

web interface for the cloud service

but it cannot run the windows

application it can just provide an

interface therefore it may send the

input data

to a windows based application server so

this web server

is running on linux and it has some

interface with which the the client can

interact but it cannot process

uh something some application which can

only run on a windows so it has to

contact

the application server which will be

running on windows

and then it will run that application

therefore may it may send input data to

a windows based server and the

application

server can process the data and then

return the result

to the web server once processing is

done

and which can be output

as the form of result on a web browser

so it can be sent to the client

so you see that here it's necessary

it cannot do it cannot be done on the

web server

so this is some intuition why we need

application server

just one of the reasons is that it

provides the environment

to run a specific application web server

may not have that environment

and it's more powerful it provides

processing power

memory as well as environment

so i hope i was able to clear your some

of your doubts regarding web server and

application server

thank you