1 Chapter 2 Infrastructure for Electronic Commerce

2 Learning Objectives In this chapter, you will learn about: The general structure of the network Protocols of electronic commerce and e- mail Internet utility programs Popular Internet applications

3 Learning Objectives This history and use of Web markup languages Web client and server architecture Differences and similarities between the Internet, intranets, and extranets Cost and bandwidth of connecting to the Internet

4 E-commerce Technology The Internet Database software Network switches and hubs Encryption hardware and software Multimedia support World Wide Web

5 Packet-Switched Networks Circuit switching is used in telephone communication. The Internet uses packet switching. Packet switching needs the computers called routers and the programs called routing algorithms

6 ARPANET ARPANET is the earliest packet-switched network. This wide area network used the Network Control Protocol (NCP). A protocol is a collection of rules for formatting, ordering, and error-checking data sent across a network.

7 Open Architecture of ARPANET Independent networks should not require any internal changes in order to be connected to the network. Packets that do not arrive at their destinations must be retransmitted from their source network. The router computers do not retain information about the packets that they handle. No global control exists over the network. Click to see Figure 2-1

8

9 The TCP/IP Protocol The Transmission Control Protocol (TCP) and the Internet Protocol (IP) are the two protocols that support the Internet operation. TCP controls the assembly of a message into smaller packets before it is transmitted over the Internet. The IP protocol includes rules for routing individual data packets from their source to their destination.

10 TCP/IP Architecture TCP/IP Protocol layers (from the highest to the lowest): Application Transport Internet Network Interface Hardware Click to see Figure 2-2

11

12 IP Address Internet addresses are based on a 32-bit number called an IP address. IP addresses appear as a series of up to four separate numbers delineated by a period. An address such as uniquely identifies a computer connected to the Internet.

13 Domain Names A Uniform Resource Locator (URL) consists of names and abbreviations that are much easier to remember than IP addresses. The HTTP protocol defines how an Internet resource is accessed. An address such as is called a domain name. Click to see Figure 2-3

14

15 HTTP Hypertext Transfer Protocol (HTTP) is responsible for transferring and displaying Web pages. A user’s Web browser opens an HTTP session and sends a request for a Web page to a remote server. In response, the sever creates an HTTP response message that is sent back to the client’s Web browser.

16 SMTP, POP, and IMAP is sent across the Internet is managed and stored by mail servers. Simple Mail Transfer Protocol (SMTP) is the standard for client program. Post Office Protocol (POP) is the standard for server program. The Interactive Mail Access Protocol (IMAP) is a newer protocol.

17 FTP The File Transfer Protocol (FTP) implements a mechanism to transfer files between TCP/IP-connected computers. FTP transfers both binary and ASCII text. Full privilege FTP allows remote uploading and downloading files. Anonymous FTP allows you to log on as a guest.

18 Internet Utility Programs Finger Ping Tracert Other route-tracing programs Click to see Figure 2-4:

19

20 Internet Applications Three representative Internet applications: Electronic mail Telnet FTP Click to see Figure 2-6: Click to see Figure 2-7: Click to see Figure 2-8:

21

22

23

24 Overview of Markup Languages SGML is a rich meta language that is useful for defining markup languages. HTML is particularly useful for displaying Web pages. XML defines data structures for electronic commerce.

25 Standard Generalized Markup Language The ISO adopted SGML standard in SGML is nonproprietary and platform- independent. SGML supports user-defined tags and architecture to complement the required richness of documents.

26 Hypertext Markup Language Tim Berners-Lee invented HTML. HTML is a document production language that includes a set of tags that define the format and style of a document. HTML is based on SGML. HTML is an instance of one particular SGML document type – Document Type Definition (DTD).

27 Extensible Markup Language XML is a descendant of SGML. XML allows designers to easily describe and deliver structured data from any application in a standard, consistent way. XML can be embedded within an HTML document. XML allows you to create your own customized markup language. Click to see Figure 2.9

28

29 HTML Tags An HTML document contains both document content and tags. The tags are the HTML codes inserted in a document to specify the format on screen. Each tag is enclosed in brackets ( ). Most tags are two-sided – opening and closing tags.

30 HTML Links Hyperlinks are bits of text that connect the current document to: –Another location in the same document –Another document on the same host machine –Another document on the Internet Hyperlinks are created using the HTML anchor tag. Two popular link structures: –Linear hyperlink structure –Hierarchical hyperlink structure Click to see Figure 2-14:

31

32 HTML Version History HTML version 1.0 was introduced in HTML 2.0 was released in Sept HTML 3.2 was introduced in HTML 4.0 was released by W3C in Dec HTML 4.01 was released in Dec XHTML 1.0 became a W3C recommendation in Jan

33 HTML Editors Low end editor displays HTML code on the screen and allow you to insert HTML tag pairs by clicking selected buttons. High end editor are Web site builder programs, they provide a rich environment that displays the Web page, not the HTML code. Microsoft FrontPage and Macromedia Dreamweaver are examples of Web site builders. Click to see Figure 2-15:

34

35 Web Clients and Severs Your PC is a Web client in a worldwide client/server network. Web software is platform-neutral. Computers that are connected to the Internet and contain documents made publicly available are called Web servers. Click to see Figure 2-16:

36

37 Web Client/Server Architecture Client/server architecture may be used on LANs, WANs, and the Web. The server’s workload is heavy, it needs to be high-ended computers with lots of disk capacity, fault-tolerant processors, and ample memory. The term thin client describes a client’s relatively low workload, compared with that of a server.

38 Two-Tier Client/Server A two-tier architecture is one in which only a client (tier 1) and a server (tier 2) are involved in the requests and the responses that flow between them over the Internet. A typical request message from a client to a server consists of three major parts: –A request line –Optional request headers –An optional entity body Click to see Figure 2-17: Click to see Figure 2-18:

39

40

41 Three-Tier Client/Server A three-tier architecture builds on the traditional two-tier approach. The first tier is the client, the second tier is the Web server, and the third tier consists of applications and their databases. A Common Gateway Interface (CGI) is a protocol which allows Web servers to interact dynamically with clients. Click to see Figure 2-19:

42 Intranets An intranet is a Web-based private network that hosts Internet applications on a LAN. Intranets are an extremely popular and low-cost way to distribute corporate information. The intranet infrastructure includes a TCP/IP network, Web authoring software, Web server hardware and software, Web clients, and a firewall server.

43

44 Intranet Benefits Increased, less expensive, environmentally friendly internal communication. Low acquisition and deployment costs. Low maintenance costs. Increased information accessibility. Timely, current information availability. Easy information publication, distribution, and training.

45 Extranets Extranets connect companies with suppliers or other business partners. An extranet can be: a public network, a secure (private) network, or a virtual private network (VPN). Extranets provide the private infrastructure for companies to coordinate their purchase and communications with one another.

46 Extranets A public network extranet exists when an organization allows the public to access its intranet from any public network. 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 “tunneling”. Click to see Figure 2-20: Click to see Figure 2-21:

47

48

49 Internet Connectivity Internet Service Providers (ISPs) provide Internet access services to other businesses. Ways to connect to an ISP: –Dial-up connection –DSL connection –ISDN connection –Cable connection –T1 connection –T3 connection Click to see Figure 2-22:

50