term client-server refers to a popular model for computer networking
that utilizes client and server devices each designed for specific purposes.
The client-server model can be used on the Internet as well as local area
networks (LANs). Examples of client-server systems on the Internet include Web
browsers and Web servers, FTP clients and servers, and DNS.
popularity many years ago as personal computers (PCs) became the common
alternative to older mainframe computers. Client devices are typically
PCs with network software applications installed that request and receive
information over the network. Mobile devices as well as desktop computers can
both function as clients.
files and databases including more complex applications like Web sites. Server
devices often feature higher-powered central processors, more memory, and
larger disk drives than clients.
or abbreviated P2P, a type of network in which each workstation has
equivalent capabilities and responsibilities. This differs from client/server
architectures, in which some computers are dedicated to serving
the others. Peer-to-peer networks are generally simpler, but they usually do
not offer the same performance under heavy loads.
created when two or more PCs are connected and share resources without going
through a separate server computer. A P2P network can be an ad hoc connection—a
couple of computers connected via a Universal Serial Bus to transfer files. A
P2P network also can be a permanent infrastructure that links a half-dozen
computers in a small office over copper wires. Or a P2P network can be a
network on a much grander scale in which special protocols and applications set
up direct relationships among users over the Internet.
between client server and peer to peer network:
peer-to-peer and client-server networks connect computers so that resources
such as files and applications can be shared. Peer-to-peer networks connect
computers so that each computer shares all or part of its resources.
Client-server networks have a central computer that holds the data and manages
- Peer-to-peer networks involve two or more
computers pooling individual resources such as disk drives, CD-ROMs and
printers. These shared resources are available to every computer in the
network. Each computer acts as both the client and the server. Each
computer communicates directly with the other computers and can add or
remove resources to the network at will.
- A client-server network involves multiple
clients connecting to a single, central server. Public data and applications
are only installed on the server. The client computers connect over the
network in order to use the resources. Servers often have private user
directories as well as multiple public directories.
- In a peer to peer network, a software application
can be installed on a single computer and shared by every computer in the
network. They also are cheaper to set up because most desktop operating
systems have the software required for the network installed by default.
- Client-server networks tend to have faster
access speeds because of the large number of clients they are designed to
support. The clients are allowed to function as workstations without
sharing any resources. It is easier to upgrade software applications and
files because they are held on one single computer. System wide services
can be provided through the server software. Security is enhanced on a
client server network because the security is handled by the server.
Client-server networks can be extended in order to handle organizational
growth. The extent of the growth is only dependent on the hardware
- Peer-to-peer networks are typically less secure
than a client-server network because security is handled by the individual
computers, not on the network as a whole. The resources of the computers
in the network can become overburdened as they have to support not only
the workstation user, but also the requests from network users. It is also
difficult to provide system wide services because the desktop operating
system typically used in this type of network is incapable of hosting the
- Client-server networks have a higher initial
setup cost. It is possible to set up a server on a desktop computer, but
it is recommended that businesses invest in enterprise-class hardware and
software. They also require a greater level of expertise to configure and
manage the server hardware and software.
- Peer-to-peer networks require a software
application to be installed on each computer in the network in order for
the computer to connect and share resources. The application is typically
installed when the operating system is installed, but needs to be
configured to be used. If the network contains multiple operating systems,
there may be a third party application that must be installed.
- Most of the software required for a
client-server network is installed only on the server. Many different
types of software including printer, FTP and security software can be
installed on a single machine. Client computers only need to have software
that enables the computer to connect to the server. Often, the client
computers have this software installed by default.
- Email by mobile phone
- Tracking of stock-market prices
- Sports results
- News headlines
- Music downloads
popular communication method. Users typically use desktop software to receive,
read and respond to messages. Some users use web-based mail and manage messages
in a web browser like Internet Explorer. The downfall to email communication is
that anyone can send email messages to anyone else if they have (or guess) the
correct email address. This system’s Achilles heel is its simplicity and
software developers having created complex spam filters and legislators having introduced
new anti-spam legislation, the problem persists and spam continues to burden
email as a messaging medium.
messaging allows users to “chat” in real time. Users can send text
messages to anyone online and receive instant replies if the user is also
online. The “instant” fad gave way to parental fears as children made
“friends” online. With no way to confirm if “friends” are
who they represent themselves to be, and multiple security holes, instant
messaging has taken a back seat in internet communication.
and daily diaries have taken hold. Some blogs are interactive, allowing users
to respond and comment on posts. Locating topic-specific blogs that provide
relevant and interesting content on a daily basis can be a challenge. The
nature of a blog is to contain fresh public content. As our lives become more
complicated blogs are often abandoned, as they require constant updating.
the security issues and the lack of extensibility, peer-to-peer networks are
used in a home network or in an environment where growth is not expected,
security is not a concern and there is little or no need for system wide
services. Client-server networks should be used in environments where growth is
expected, security is important and faster access times are required.
enable communication between two computers. The commonly used protocols are
Transmission Control (TCP/IP), File Transfer Protocol (FTP), and Hypertext
Transfer Protocol (HTTP).
information technology, a protocol (from the Greek protocollon, which
was a leaf of paper glued to a manuscript volume, describing its contents) is
the special set of rules that end points in a telecommunication connection use
when they communicate. Protocols exist at several levels in a telecommunication
connection. For example, there are protocols for the data interchange at the
hardware device level and protocols for data interchange at the application
program level. In the standard model known as Open Systems Interconnection (OSI),
there are one or more protocols at each layer in the telecommunication exchange
that both ends of the exchange must recognize and observe. Protocols are often
described in an industry or international standard.
Transfer Protocol (HTTP) is a
networking protocol for distributed, collaborative, hypermedia information
systems. HTTP is the foundation of data communication for the World Wide Web.
Short for HyperText
the underlying protocol used by the World Wide Web. HTTP defines how messages
are formatted and transmitted, and what actions Web servers and browsers should
take in response to various commands. For example, when you enter a URL in your
browser, this actually sends an HTTP command to the Web server directing it to
fetch and transmit the requested Web page.
Protocol (FTP) is a standard network
protocol used to transfer files from one host to another host over a TCP-based network, such as the Internet. FTP
is built on a client-server architecture and utilizes separate
control and data connections between the client and server.
FTP users may authenticate themselves using a clear-text sign-in protocol but
can connect anonymously if the server is configured to allow it.
client applications were interactive command-line tools, implementing standard
commands and syntax.
exchanging files over
the Internet. FTP
works in the same way as HTTP
for transferring Web pages from a server to a user’s
browser and SMTP for
mail across the Internet in that, like these technologies, FTP uses the
protocols to enable data transfer.
commonly used to download
a file from a server using the Internet or to upload a file to a
server (e.g., uploading a Web page file to a server).
Markup Language (HTML) is the predominant markup
language for web pages. HTML elements are the basic building-blocks of WebPages.
the form of HTML elements consisting of tags, enclosed in angle
brackets (like <html>), within the web page content. HTML tags most
commonly come in pairs like <h1> and </h1>, although some tags,
known as empty elements, are unpaired, for example <img>. The
first tag in a pair is the start tag, the second tag is the end tag
(they are also called opening tags and closing tags). In between
these tags web designers can add text, tags, comments, and other types of
is to read HTML documents and compose them into visible or audible web pages.
The browser does not display the HTML tags, but uses the tags to interpret the
content of the page.
Web (abbreviated as WWW or W3 and commonly known as the
Web) is a system of interlinked hypertext documents
accessed via the Internet. With a web browser,
one can view web
pages that may contain text, images, videos, and other multimedia
between them via hyperlinks.
from earlier hypertext systems, British engineer and computer
scientist Sir Tim Berners-Lee, now Director of the World Wide Web Consortium (W3C), wrote a
proposal in March 1989 for what would eventually become the World Wide Web.
At CERN in Geneva,
Switzerland, Berners-Lee and Belgian computer scientist Robert
Cailliau proposed in 1990 to use hypertext “… to link and access
information of various kinds as a web of nodes in which the user can browse at
and they publicly introduced the project in December.
(WAP) is a technical standard for accessing information
over a mobile wireless network. A WAP browser is a web browser
devices such as mobile phones (called “cellular
phones” in some countries) that uses the protocol.
mobile service providers had limited opportunities to offer interactive data
services, but needed interactivity to support Internet
applications such as:
nuances and benefits of the different forms.
groups, like small
rural communities or a neighborhood subdivision, if you will. Although social
networking is possible in person, especially in the workplace, universities,
and high schools, it is most popular online. When it comes to online social
networking, websites are commonly used. These websites are known as social
Protocol address (IP address) is a numerical label assigned to each
device (e.g., computer, printer) participating in a computer
network that uses the Internet
Protocol for communication.
An IP address serves two principal functions: host or network interface identification and location addressing.
Its role has been characterized as follows: “A name indicates
what we seek. An address indicates where it is. A route indicates how to get
has a unique identifying number, called an IP Address. A typical IP address
looks like this:
there was the public internet there was the internet’s forerunner ARPAnet or
Advanced Research Projects Agency Networks. ARPAnet was funded by the United
States military after the cold war with the aim of having a military command
and control center that could withstand nuclear attack. The point was to
distribute information between geographically dispersed computers. ARPAnet
created the TCP/IP communications standard, which defines data transfer on the
Internet today. The ARPAnet opened in 1969 and was quickly usurped by civilian
computer nerds who had now found a way to share the few great computers that
existed at that time.
never-ending worldwide conversation.” – Supreme judge statement on
considering first amendment rights for Internet users.
a cold war kind of day, in swinging 1969, work began on the ARPAnet,
grandfather to the Internet. Designed as a computer version of the nuclear bomb
shelter, ARPAnet protected the flow of information between military
installations by creating a network of geographically separated computers that
could exchange information via a newly developed protocol (rule for how
computers interact) called NCP (Network Control Protocol).
The first trans-Atlantic connection and the popularity of emailing
The beginning of TCP/IP
The email client
The PC modem
The Bulletin Board System (BBS)
Spam is born
MUD – The earliest form of multiplayer games
The first emoticon
Arpanet computers switch over to TCP/IP
Domain Name System (DNS)
The Internet grows
IRC – Internet Relay Chat
First major malicious internet-based attack
AOL is launched
The proposal for the World Wide Web
First commercial dial-up ISP
World Wide Web protocols finished
First web page created
First content-based search protocol
MP3 becomes a standard
The first webcam
Mosaic – first graphical web browser for the general public
Governments join in on the fun
Commercialization of the internet
First web-based (webmail) service
The term “weblog” is coined
First new story to be broken online instead of traditional media
Internet-based file-sharing gets its roots
The bubble bursts
Wikipedia is launched
VoIP goes mainstream
MySpace becomes the most popular social network
CAN-SPAM Act puts a lid on unsolicited emails
Social Media and Digg
launched in 2004, though at the time it was only open to college students
and was called “The Facebook”; later on, “The” was dropped
from the name, though the URL http://www.thefacebook.com
launched in 2005, bringing free online video hosting and sharing to the masses.
launched in 2006. It was originally going to be called twitter (inspired
by Flickr); the first Twitter message was “just setting up my twttr”.
almost certainly the iPhone,
which was almost wholly responsible for renewed interest in mobile web
applications and design.