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How does a Server work?
View the presentation
below to understand how a server works:
Web servers are responsible for storing
and exchanging information with other machines. Because of
this, at least two participants are required for each
exchange of information: a client, which requests the
information, and a server, which stores it. Each side also
requires a piece of software to negotiate the exchange of
data; in the case of the client, a browser like Netscape
or Internet Explorer is used.
On the server side, however, things are
not as simple. There is a myriad of software options
available, but they all have a similar task: to negotiate
data transfers between clients and servers via HyperText
Transfer Protocol, the communications protocol of the Web.
What type of server software you are able to run depends
on the Operating System chosen for the server. For
example, Microsoft Internet Information Server is a
popular choice for Windows NT, while many Unix fans choose
Apache Web server.
A simple exchange between the client
machine and Web server goes like this:
1. The client's browser dissects the URL
in to a number of separate parts, including address, path
name and protocol.
2. A Domain Name Server (DNS) translates the domain name
the user has entered in to its IP address, a numeric
combination that represents the site's true address on the
Internet (a domain name is merely a "front" to
make site addresses easier to remember).
3. The browser now determines which protocol (the language
client machines use to communicate with servers) should be
used. Examples of protocols include FTP, or File Transfer
Protocol, and HTTP, HyperText Transfer Protocol.
4. The server sends a GET request to the Web server to
retrieve the address it has been given. For example, when
a user types http://www.example.com/1.jpg, the browser
sends a GET 1.jpg command to example.com and waits for a
response. The server now responds to the browser's
requests. It verifies that the given address exists, finds
the necessary files, runs the appropriate scripts,
exchanges cookies if necessary, and returns the results
back to the browser. If it cannot locate the file, the
server sends an error message to the client.
5. The browser translates the data it has been given in to
HTML and displays the results to the user.
This process is repeated until the client
browser leaves the site.
Aside from its functions listed above, the
Web server also has an additional number of
responsibilities. Whereas a Web browser simply translates
and displays data it is fed, a Web server is responsible
for distinguishing between various error and data types. A
Web server must, for example, designate the proper code
for any sort of internal error and send that back to the
browser immediately after it occurs. It also has to
distinguish between various elements on a Web page (such
as .GIFs, JPEGS and audio files) so that the browser knows
which files are saved in which format. Depending on the
site's function, a Web server may also have numerous
additional tasks to handle, including logging statistics,
handling security and encryption, serving images for other
sites (for banners, pictures, etc), generating dynamic
content, or managing e-commerce functions.
Now that you've had a behind-the-scenes
tour of a Web server, you can appreciate all the work that
goes in to delivering a single page of content to your
computer screen. Use this knowledge to your advantage, and
keep it in mind when shopping around for your next host.
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