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 commerce

The computers in these networks run such software as:

• Operating systems, database managers, encryption software, multimedia creation and viewing software, and the graphical user interface

The Internet includes:• 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

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 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

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

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

• Independent networks should not require any internal changes to be connected to the network.

• Packets that do not arrive at their destinations must be retransmitted from their source network.

• Router computers act as receive-and-forward devices; they do not retain information about the packets that they handle.

• No global control exists over the network.

Internet Protocols

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

IPv4 is based on a 32-bit binary number that allows over 4 billion unique addresses for computers to connect to the Internet

Appears in ‘dotted decimal’ notation (four numbers separated by periods)

Approximately two billion IP addresses are either in use or unavailable for use

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 Billions (2 128) more addresses Improved packet format, added security

Domain Names

To make the numbering system easier to use, an alternative addressing method that uses words was created

Domain names managed by ICANN since 1998

Domain names are protected by copyright laws 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 ‘top-level domain’ (TLD)

Original Top-level Domain Names + New Additions

Web Page Delivery

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

E-mail sent across the Internet can be read because of a common set of rules

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

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

HTML and XML are both derivatives of SGML

SGML offers a system of marking up documents that is independent of any software application

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

A simplified subset of SGML that includes tags defining the format and style of text elements in a document

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

Tags are codes that are used to define where an HTML element starts and (if necessary) where it ends

In an HTML document, each tag is enclosed in brackets (<>)

Hyperlinks are created using the HTML anchor tag Hyperlinks connect the current document to:

• another location in the same document• another document on the same host machine• another document on the Internet

Two popular link structures are:• Linear hyperlink structure• Hierarchical hyperlink structure

Markup Languages and the Web

Scripting Language and Style Sheet Capabilities

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

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.

Microsoft FrontPage and Macromedia Dreamweaver are examples of Web site builders.

HTML Editors

Extensible Markup (XML)

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)

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

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

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 higher-bandwidth connections that they can lease from telecommunications carriers

A ‘T1’ line operates at 1.544 Mbps and a ‘T3’ line operates at 44.736 Mbps

ISDN uses the DSL protocol suite to offer bandwidths between 128-256 Kbps

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

Connections that operate at speeds of greater than 200 Kbps are called broadband services

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

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