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					CSN200 Introduction to Telecommunications, Winter 2000                                       Lectures_05

                                                   Internet Applications
Reference:         Chapter-2,          Business Data Communications and Networking, 6th Edition, by-
                                       Fitzgerald and Dennis.

Internet Application Software:
The most popular application the Web started in 1989 and the first popular browser appearing in 1992.
Electronic mail, Telnet and FTP have been around almost as long as the Internet itself.
Each application requires a special application layer software program running on the client computer
and a similar application layer software program running on the server.
Now a days most of the client applications incorporate all of these in one package, e.g., Netscape.

World Wide Web or Web:
Is an Internet Software applications. Each client computer needs an application layer software package
called a Web Browser, e.g., Netscape, Internet Explorer. Each server on the network needs an
application layer software package called a Web Server.

The Web, internet based hypertext system, was first conceived in 1989 by Tim Berners-Lee at the
European Laboratory for Particle Physics (CERN) in Geneva.
Mosaic, the first graphical Web browser was developed by Marc Andreessen and his team at the
University of Illinois, as part of a project NCSA (National Centre for Supercomputing Applications).
 It uses URLs (Universal Resource Locators) as addresses to information on the Internet, in the
   form of recently known as URIs (Universal Resource
 It uses the HyperText Transfer Protocol (HTTP)
 An HTTP request from a Web browser to a Web server has three parts:
       1. Request line - includes a command, UPL and HTTP version number.
       2. Request header - optional - browser used, date, user ID, password
       3. Request body - information sent to the server, e.g., a form
 Every web access must provide the Internet address of the requester's computer.
 The HTTP response from the server to the browser is similar to the browser request. It has three
       1. Response status - HTTP version number, status code, reason phrase
       2. Response header - web server used, date, URL, the format used, e.g., HTML, Microsoft
           Word, adobe PDF
       3. Response body - the Web page itself
 Hypertext enables user to access information non-linearly by following links.
 Hypertext uses the HyperText Markup Language (HTML), standard produced by IETF and W3C
   (WWW Consortium)

Finding Information:
1. Using a URL pointed by a friend, book, advert, professor, etc.
2. Using a link from one page to another
3. Using a search engine.

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Search Engine:
Search engines are Web sites that routinely use software spiders to explore the Web.
These spiders methodically search all the pages on all the Web sites they can find and report back their
The search engine builds an index to these pages based on the words they contain
When you connect to a search engine, you type a few words describing what you want. The search
engine will search its index for these keywords and provide you with a list of pages that contain them.

Three best search engines:
   1. Yahoo ( - small or obscure Web sites are excluded
   2. AltaVista ( - best choice for obscure topics
   3. Excite ( - uses advance artificial intelligence techniques

Metasearch engine:
      MetaCrawler ( - it simultaneously sends the request to many search
      engines and then compiles the information received from all search engines into one display.

Is also called "push" technology. It is opposite to the Web searching for information (a "pull"
Here the users have to sign up for a type of information on a set of channels. And permits the Web
server to push the information as it becomes available. It is like a TV, as the content and time is chosen
by the Webcaster, the user merely chooses the channels.

Electronic Mail:
One of the earliest applications on the Internet.
The most heavily used one.
With email, users create and send messages to
         - one user,
         - several users, or
         - all users on a distribution list.
Enables users to send text messages and attach files from word processors, graphic programs, etc.
Allows prioritizing and organize messages.
It is fast - takes seconds, minutes, or hours not days.
Cheaper compared to regular mail.
Can substitute for telephone voice messages.

E-mail Standards:
Standards have been developed to ensure compatibility between different e-mail software packages.
Three common standards are:
       1. SMTP
       2. X.400
       3. CMC

E-mail packages are designed to send using one standard but can understand messages received in
several different standards.
E-mailing needs two kinds of software:
   1. User agent - on Client computers
   2. Mail transfer agent - on Mail servers

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CSN200 Introduction to Telecommunications, Winter 2000                                      Lectures_05

The user writes the e-mail message using one of these user agents (Pegasus mail, Netscape mail, etc),
which formats the message into two parts:
   1. The header - source, destination email addresses, date,                          subject, etc.
   2. The body - the message itself

The user agent sends the message (header and body) to a mail server that runs a special application
layer software called message transfer agent. These agents read the envelopes and then send the
message through the network to the receiver's mail server.
The user agent contacts the server and asks for the contents of the user's mailbox.
SMTP is the standard used on the Internet between message transfer agents
As the name suggests, it only permits the transfer of text messages.

For non-text files several standards operate with SMTP are (allows graphics and binary files to be
attached to e-mail messages):
       MIME - Multipurpose Internet Mail Extension protocol
       Uuencode - Unix-To-Unix Encoding - is used to format a binary file so that it can be sent over
                       media that do not support any format other than simple ASCII data.
       Binhex - Binary Hexadecimal

POP (Post Office Protocol) is the standard used to transfer messages between message transfer
agents and the user agents.
       POP is being replaced by IMAP (Internet Mail Access Protocol)

X.400 was developed by CCITT in 1984 - is a set seven standards that define how e-mail is to be
processed by user agents and mail transfer agents.

CMC (Common Messaging Calls) is a simpler version of X.400 and was developed by CCITT, IBM,
Lotus, Microsoft in 1994.

Email Directories:
Several commercial firms are trying to build e-mail directories, e.g.,
Several competing standards have been developed in an attempt to provide universal directory service.
X.500 is the directory service standard for X.400 mail users.
LDAP (Lightweight Directory Access Protocol) is a subset of X.500 and Netscape has adopted it for e-
mail directory services. It is simple and small but lacks important features.

FTP (File Transfer Protocol):
FTP enables you to send and receive files over the Internet.
It requires an application layer program on the client computer and a FTP server application program
on a server.
Two types of FTP sites:
Closed and anonymous - requires an account name and password.

Telnet enables users of one computer to login to other computers on the Internet. It requires an
application layer program on the client computer and an application layer program on the server or
host computer. Needs an account name and a password.
It is useful because it enables you to access your server or host computer without sitting at its

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keyboard. It also poses security threat.

Groupware is a software that helps groups of people to work together more productively.
Groupware applications are often organized using a two-by-two grid. Groupware permits people in
different places to communicate either at the same time or at different times. It also allows
communicate either at the same time or at different times.
It allows people to exchange ideas, debate issues, make decisions, and write reports without actually
having to meet face-to-face. It even improves the meeting in the same room. It also helps group make
decision faster.
Four popular types of groupware are:
    1. Discussion groups
    2. Document-based groupware
    3. Group support system
    4. Video conferencing

Discussion groups:
Are collections of users who have joined together to discuss some topic. Two commonly used groups
are Usenet newsgroups and listservs.
Usenet newsgroups are the most formally organized of the discussion groups. Usenet newsgroups are
a set of huge bulletin boards on which anyone who wishes can read and post messages. The usenet
newsfeed of the discussions within each of these groups is available to all computers on the Internet
(70MB), but some choose to keep less.
The general process is to subscribe to a specific topic or set of topics. Once you have subscribed, each
time you access the newsgroups, you are informed of any new messages added to the topics.

Listservs is similar in concept to the usenet newsgroups, but is less formal. Listserv is simply is a
mailing list. It has two parts:
Listserv processor - processes commands - such as subscribe, unsubscribe, etc.
Listserv mailer - routes messages to everyone on the mailing list.
To use a listserv, you need to know the addresses of both the processor and the mailer.
To subscribe to a listserv, you send an e-mail message to the listserv processor, which adds your name
to the list, e.g.,
To send a message to everyone on a listserv, you would e-mail your message to the group, e.g.,
There is no centrally managed list of listservs.
To get a list of most popular listservs, send an email to any listserv with the message list global.

Document-Based Groupware:
- are softwares to support an ongoing discussion in a structured way, in contrast to seperate e-mail
Lotus Notes ( also called Domino), a document database designed to store and manage large
collections of text and graphics, was the first product to provide a solution
Documents can have different sections, can be organized into a hierarchical structure of sections,
documents, and folders.
Microsoft Exchange, Outlook Express, Netscape does sort the e-mail in folders that's all.
In Lotus notes, a portion of the report could be passed to other team members for editing or comments.
It can also automate certain document-based processes, called work-flow automation, e.g., insurance

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Group Support Systems:
Both e-mail document-based groupware are not very suited to support the needs of groups working
together at the same time in the same place. Also those are not tools helping groups making decisions.
These are softwares designed to improve group decision making.
Try the Alan Dennis's TCBWorks at the site
Most GSS are used in special-purpose meeting rooms that provide each member with a networked
computer, plus large-screen video projection that allows participants to communicate, propose ideas,
analyze options, evaluate alternatives, and so on.
This way everyone has the same opportunity to contribute, and ideas can be collected much faster.
Also allows anonymous comments.
It can reduce time to make decisions by 50 to 80 percent.

Videoconferencing provides real-time transmission of video and audio signals to enable group
members in two or more locations to have a meeting.
Software example - CUSeeMe.
It transmits images across a network to application software on a server. The server then sends the
signals to the other client computers.
The transmission of video requires a lot of network capacity. Most videoconferencing uses data
compression to reduce the amount of data transmitted.

Telecommunications plan goes ahead
(Sault Star article by- Elaine, 18 Sep'98; collected by Dwight)
The development of a fibre-optic telecommunications network began in April'98 by the ADNet
(Algoma District Network) under the Crysalis Project for the Northern community. ADNet is one of
the five separate working groups. The expected cost would be $60 million.

    Improved communication will result in increased productivity, as in the information society the
     primary task of most office workers is the processing and communication of information.

Electronic Commerce:
Almost all large companies use the Internet for electronic commerce - doing business on the Internet.
Internet is being used for selling products but more providing consulting, tools, training, and services.

There are four major ways using Internet to support electronic commerce:
   1. Electronic Store
   2. Electronic Marketing Site
   3. Information/Entertainment Provider
   4. Customer Service Site

Electronic Store
Internet equivalent of a local store
Mail-order catalogue
The companies develop Web site that lists all of the products and services.
e.g., The Boeing electronic store (an extranet)
Del sells almost $1 billion of computers per year from its Web site alone.
 In future you might be shopping on the Internet using virtual reality, as if you are in the shop and
    picking up the goods to buy.
Electronic mall - collection of electronic stores; the idea of mall is not very successful on the Internet.

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Electronic Marketing Site
This type of site supports the sales process, but not make the actual sales.
It is cheaper than TV and news paper advertisements.

Information/Entertainment Provider
Supplies information or entertainment.
Provides intangible things compared to physical goods in electronic stores.
e.g., Search Engines

Customer Service Site
Provides variety of information for customers after they have purchased a product or service.
Those can be:
    Technical support information
    Service information
    Frequently asked questions
    Upgrades of softwares

Uuencode - Unix-To-Unix Encoding - is used to format a binary file so that it can be sent over media
that do not support any format other than simple ASCII data. Electronic mail or USENET news are
examples of such media. The uuencode program encodes the file so that it contains only ASCII
characters. The file can then be restored to normal via the uudecode command.

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