Transcript Chapter 2 EC Technology Infrastructure: The Internet and the World Wide Web Technology Overview  Computer networks and the Internet form the basic technology structure for electronic.

Chapter 2
EC Technology Infrastructure:
The Internet and the World
Wide Web
Technology Overview
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Computer networks and the Internet form the basic
technology structure for electronic commerce
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The computers in these networks run such software
as:
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The Internet includes:
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Operating systems, database managers, encryption
software, multimedia creation and viewing software,
and the graphical user interface
The hardware that connects the computers together
and the telecommunications lines that connect the
networks together
Rapid change in these technologies requires
businesses to be flexible
Packet-Switched Networks
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A local area network (LAN) is a network of computers
close together
A wide area network (WAN) is a network of computers
connected over a great distance
Circuits form a single electrical path between origin
and destination, ie. telephone communication
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Single connection model - circuit switching
The Internet uses packet switching
• Files broken down into packets that are labeled with
their origin, sequence, and destination addresses
Routing Packets
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The computers that decide how best to forward each
packet in a packet-switched network are called ‘routers’
The programs on these routers use ‘routing algorithms’
that call upon their ‘routing tables’ to determine the
best path to send each packet
When packets leave a network to travel on the Internet,
they are translated into a standard format by the router
These major routers and the telecommunication lines
connecting them are referred to as ‘the Internet
backbone’
ARPANET was the earliest packet-switched network
Routing Packets
Internet Protocols
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A protocol is a collection of rules for formatting,
ordering, and error-checking data sent across a network
The open architecture of this experimental network
used Network Control Protocol (NCP) which later
became the core of the Internet
This open architecture has four key rules that have
contributed the success of the Internet
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Independent networks should not require any internal changes to
be connected to the network.
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Packets that do not arrive at their destinations must be
retransmitted from their source network.
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Router computers act as receive-and-forward devices; they do not
retain information about the packets that they handle.
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No global control exists over the network.
Internet Protocols
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Transmission Control Protocol (TCP) and Internet
Protocol (IP) are the two protocols that support the
Internet operation (commonly referred to as TCP/IP)
TCP controls the disassembly of a message into
packets before it is transmitted over the Internet and
the reassembly of those packets when they reach their
destination
IP specifies the addressing details for each packet
being transmitted.
The IP version is use for the past 20+ years was IPv4.
IP Addresses
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IPv4 is based on a 32-bit binary number that allows
over 4 billion unique addresses for computers to
connect to the Internet
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Appears in ‘dotted decimal’ notation (four numbers
separated by periods)
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Approximately two billion IP addresses are either in
use or unavailable for use
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Private IP addresses are IP numbers that have been
set aside for subnet use and are not permitted on the
Internet (10-nets, or 192 series)
IPv6 is an alternative solution that uses a 128-bit
hexadecimal number for addresses
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Billions (2 128) more addresses
Improved packet format, added security
Domain Names
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To make the numbering system easier to use, an
alternative addressing method that uses words was
created
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Domain names managed by ICANN since 1998
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Domain names are protected by copyright laws
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Case of: mikerowesoft.com
(WSJ 1/19/04)
The last part of a domain name (i.e., ‘.com’) is the
most general identifier in the name and is called a ‘toplevel domain’ (TLD)
Original Top-level Domain Names
+ New Additions
Web Page Delivery
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Hypertext Transfer Protocol (HTTP) is the set of rules
for delivering Web pages over the Internet
HTTP uses the client/server model
• Web browser opens an HTTP session and sends a
request for a Web page to a remote server
• In response, the server creates an HTTP response
message that is sent back to the client’s Web
browser
The combination of the protocol name and the
domain name is called a uniform resource locator
(URL)
SMTP, POP, MIME, and IMAP
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E-mail sent across the Internet can be read because of
a common set of rules
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Simple Mail Transfer Protocol (SMTP) specifies the exact
format of a mail message and describes how mail is to be
administered at the Internet and network level
An e-mail program running on a user’s computer can
request mail from the company’s main e-mail computer
using the Post Office Protocol (POP)
Multipurpose Internet Mail Extensions (MIME) allow the
user to attach binary files to e-mail
The Interactive Mail Access Protocol (IMAP) performs the
same basic functions as POP, but includes additional
features, such as viewing headers only before
downloading mail messages
Markup Languages and the Web
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Web pages are marked with tags to indicate the display
and formatting of page elements
SGML is a meta language, which is a language that can be
used to define other languages
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HTML and XML are both derivatives of SGML
SGML offers a system of marking up documents that is
independent of any software application
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Advantages of SGML include its long-term viability, it is
nonproprietary and platform-independent, and it supports
user-defined tags and architectures
Disadvantages of SGML include a costly and complicated set
up, expensive tools, creating document-type definitions that
are time consuming, and extensive learning time
Hypertext Markup Language
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A simplified subset of SGML that includes tags defining the
format and style of text elements in a document
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Tags are codes that are used to define where an HTML
element starts and (if necessary) where it ends
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In an HTML document, each tag is enclosed in brackets (<>)
Hyperlinks are created using the HTML anchor tag
Hyperlinks connect the current document to:
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HTML is an instance of one particular SGML document type
HTML includes tags for tables, frames, and other features that
help Web designers create more complex page layouts
another location in the same document
another document on the same host machine
another document on the Internet
Two popular link structures are:
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Linear hyperlink structure
Hierarchical hyperlink structure
Markup Languages and the Web
Scripting Language and Style
Sheet Capabilities
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Web designers can use OBJECT tags to embed scripting
language codes in HTML pages (this is also called client-side
scripting) for interaction or data collection
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Scripts can execute programs on computers that display those
pages
Examples include JavaScript, Jscript, VBscript, Perl
Cascading Style Sheets (CSS) let designers define formatting
styles that can be reapplied to multiple Web pages.
Sophisticated editors can create full-scale, commercial-grade
Web sites with database access, graphics, fill-in forms, and
display the Web page along with the HTML code.
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Microsoft FrontPage and Macromedia Dreamweaver are examples
of Web site builders.
HTML Editors
Extensible Markup (XML)
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Unlike HTML, XML uses markup tags to describe the
meaning of the text rather than just its display
characteristics
XML includes data about data (metadata)
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XML uses paired start and stop tags in much the same
way as database software defines a record structure
An XML document can be embedded within an HTML
document, with an XSL stylesheet to define
appearance
XML allows a user to ‘extend’ the language by creating
their own tags, now being standardized within
industries: ebXML, XBRL, LegalXML, MathML
Intranets and Extranets
Intranets
• Interconnected networks that do not extend beyond
organization boundaries
• Extremely popular and low-cost way to distribute
corporate information
• Intranets use Web browsers and Internet-based
protocols (including TCP/IP, FTP, Telnet, HTML, and
HTTP) and reside inside the firewall
Extranets
• Intranets extended to include specific entities outside
the boundaries of the organization (business partners,
suppliers, etc.).
• Can be a public network, a secure (private) network,
or a virtual private network (VPN).
Intranets and Extranets
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A public network is any computer or
telecommunications network that is available to the
public.
A private network is a private, leased-line connection
between two companies that physically connects their
intranets to one another.
A VPN extranet is a network that uses public networks
and their protocols to send sensitive data to partners,
customers, suppliers, and employees using a system
called ‘IP tunneling’ or ‘encapsulation’.
Connectivity Overview
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Bandwidth is the amount of data that can travel through
a communication line per unit of time
Large firms can connect to an ISP using higherbandwidth connections that they can lease from
telecommunications carriers
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A ‘T1’ line operates at 1.544 Mbps and a ‘T3’ line
operates at 44.736 Mbps
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ISDN uses the DSL protocol suite to offer bandwidths
between 128-256 Kbps
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The term m-commerce (mobile commerce) is used to
describe the kinds of resources people might want to
access using devices that have wireless connections
Broadband Connections
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Connections that operate at speeds of greater than 200
Kbps are called broadband services
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ADSL uses the DSL protocol to provide bandwidths
between 100-640 Kbps upstream and 1.5-9 Mbps
downstream
Cable modems provide transmission speeds between 300
Kbps-1 Mbps from the client to the server and a
downstream rate as high as 10 Mbps
Satellite microwave transmissions handle Internet
downloads at speeds around 500 Kbps
Wireless service (primarily satellite w/microwave
transmitters) is gradually improving as an alternative
Internet Options
Internet2
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Internet2 is an experimental test bed for new
networking technologies that is separate from
the original Internet
200 universities and a number of corporations
joined together to create this network
It has achieved bandwidths of 10 Gbps
Internet2 promises to be the proving ground for
new technologies and applications of those
technologies that will eventually find their way to
the Internet