Page 121 - DMGT505_MANAGEMENT_INFORMATION_SYSTEM

Management Information Systems

Notes HTTP

In order to access any website, the web browsers are used which are assisted by the URL that uses
the http scheme. It is the URL or the port number that assists the browser to link with a Website.
The server indicates a computer connected to the Internet while the port number indicates a type
of socket to which the browser plugs in to link with the Web server. The web server not only
provides the requisite web pages but also describes a computer program that runs on a computer
to provide web pages. When a browser receives an URL will attempt to connect with the server
computer having the required web pages by connecting to the specified port number. The URL
can be provided to the browser either by typing it at its specified location or by clicking on the
link available on some already displayed web page or document.
It is the role of the browser to connect with the server where the requisite requests from client
or user is stored or available. When the web server receives the request from browser it replies
back to the browser, which is client in this case. The information basically contains the HTTP
protocol version, name of the server, the media type of the document and date, etc. The media
type of the document is quite important information because the browser is required to know
what kind of document this is before it can process it. HTML is the most common media type
transferred over the Web. Other media types are GIF image and JPEG image. Several times
when a response like “HTTP 404 Not Found” is displayed which means that the request document
is not available at the link. There are different responses defined in HTTP. Briefly, in order to
access a web page, HTTP involves browser that issues a request followed by a few headers. In
response, the server replies back with a few headers and a document.
The web server basically maps the URLs to files on its hard disks. The web server interprets the
path in any URL to map it with a filename on its hard disk. In order to make it work to map with
the requisite file, the web server is configured to contain a “document root” directory relative to
which all URLs are resolved as filenames. Let us take an example, suppose the URL is http://
myspace.tutorial.in, and the document root is D:\WWWFiles\. When a user types the URL
http://myspace.tutorial.in/ lesson1/networking.htm into browser, the browser requests the
server for the document/lesson1/networking.htm. The web server begins searching in the
directory D:\WWWFiles\lesson1 for a file called networking.htm. If the requisite file is available
it responds with a header followed by the document. If it is not available, it responds a 404 Not
Found followed by a helpful error message telling the user to search elsewhere.
FTP

The File Transfer Protocol is among the oldest protocols still used in the Internet. FTP is widely
available on almost all-browsers indicating that all computing platforms, including DOS, OS/2,
UNIX, and up to the mainframe level have this service available. You can very well understand
from its name that it facilitates the majority of file transfers across the Internet. In other word,
FTP is a file server access protocol that enables a user to transfer files between two hosts across
the network or Internet using TCP. You may see the versatility of this application layer protocol,
it accomplishes its job even intended hosts at separate locations could potentially be running
different operating systems, using different file storage systems, and using different character
sets. Accessing FTP sites over the Internet requires that the user must have the knowledge of the
location and the name of the desired files.
Unlike Telnet, FTP does not require any familiarity with the remote operating system. The user
is still required, however, to be familiar with the FTP command set built into the protocol itself
so that he or she can productively manage the session.

Modern FTP servers known as ftpd support two different TCP connections, namely control and
data connections. First control connection is invoked for the entire duration of transfer of file or

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