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The Internet and the World Wide Web Internet Programming Using VBScript and JavaScript 1.

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Presentation on theme: "The Internet and the World Wide Web Internet Programming Using VBScript and JavaScript 1."— Presentation transcript:

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2 The Internet and the World Wide Web Internet Programming Using VBScript and JavaScript 1

3 Objectives l In this chapter you will: l Learn how the Internet evolved from ARPANET l Identify the protocols used to transmit data across the Internet l Identify the TCP/IP utilities that can be used to locate information about a Web site l Use HTML tags to create a Web page l Create a Web page using a text editor 1

4 The History of the Internet l Today, most people access the Internet using an application called a Web browser l The most common Web browsers are Internet Explorer and Netscape Navigator l The browser is an example of a client application that allows your computer to communicate with other computers on the Internet l Many computers on the Internet are servers, which provide programs to clients l Examples of server-based programs include e- mail and Web page publishing 1

5 The History of the Internet l Programming that makes it possible for client applications to communicate with server applications in a network is referred to as client- server programming l The original Internet (then called ARPANET) consisted of a relatively small number of computers that connected government agencies and a handful of participating universities l In September 1969, ARPANET consisted of a single network between UCLA, UCSB, Utah, and the Stanford Research Institute 1

6 The History of the Internet l Each computer was called a host l By 1971 ARPANET stretched across the United States through fewer than two dozen universities l In 1976 the Internet was opened to commercial traffic l programs allow you to send electronic messages to other individuals via the Internet l Telnet programs allow you to remotely access a computer via the Internet, using the Telnet protocol 1

7 The History of the Internet l An FTP server allows FTP clients to transfer files to and from the server l FTP is part of a suite of protocols known as TCP/IP (Transmission Control Protocol/Internet Protocol) l By the late 1980’s the number of host computers on the Internet had grown to 100,000 l TCP/IP consists of a suite of protocols that allowed other programs, such as , Telnet, and FTP, to provide communication between computers via the Internet 1

8 The History of the Internet l The Internet grew as more Internet service providers (ISPs), such as CompuServe, provided access to the Internet to greater numbers of people l On June 12, 1991, a new technology provided a means to easily locate and access cross-platform documents over the Internet l These cross-platform documents, called hypertext documents, were viewable no matter which computer platform you were using l This technology involved a new language standard, called Hypertext Markup Language (HTML), and a new protocol, called Hypertext Transfer Protocol (HTTP) 1

9 The History of the Internet l HTML instructions, called tags, instructed a Web browser how to format and process a hypertext document l In 1993, the University of Illinois National Center for Supercomputing Applications (NCSA) released NCSA Mosaic, the first commercial Web browser 1

10 The History of the Internet l Hypertext documents that are shared on the Internet are called Web pages, and the location address of these documents is known as a Uniform Resource Locator (URL) l Today the Internet is described as a global information system that uses TCP/IP to provide communications services l Many companies are currently developing Internet-based applications to facilitate e- commerce transactions 1

11 How the Internet Works l Computers use a suite of protocols known as TCP/IP l TCP/IP includes a variety of other protocols: TCP, IP, Telnet, FTP, HTTP, Simple Mail Transfer Protocol (SMTP), and Network News Transfer Protocol (NNTP) l While TCP/IP establishes the basic rules for communication over the Internet, other network protocols, such as NetBEUI and IPX/SPX, establish the rules for communication between computers within private networks, called Intranets 1

12 How the Internet Works l All computers that connect to the Internet, both clients and servers, must use the TCP/IP protocol l Because TCP/IP is a scaleable network protocol that can be used for local area networks (LANs) and wide area networks (WANs), most operating systems come with the TCP/IP software built in l If you have direct access to the Internet, then your computer has a copy of the TCP/IP software 1

13 Transmission Control Protocol (TCP) l TCP splits the transmission into small packets, which are sent over the Internet to a destination computer l The TCP software on the destination computer reassembles the packets into the original transmission l En route to the destination computer, each data packet makes several stops, called hops, at one or more computers along the way l The computer at each stop is sometimes referred to as the gateway computer, because it plots the next leg of the journey and sends the packet on its way 1

14 Internet Protocol (IP) l The Internet Protocol uses an addressing scheme to manage the addressing of each individual packet, to ensure that all packets make it to their final destinations l Gateway computers use the IP address to determine how to plot where the packet should go next l Virtually all Internet traffic travels via this IP routing model 1

15 IP Address l Every computer connected to the Internet has an IP address associated with it l Each Web server has a unique computer number, such as , which is its IP address l Internet service providers (ISPs) assign a static or dynamic IP address each time a client computer connects to the Internet l A dynamic IP address will change each time the computer connects to the Internet l A static IP address is assigned to a specific computer and does not change 1

16 IP Address l A Web server must have a static address so that the routing servers on the Internet will always know the IP address for the Web site l The IP protocol defines an IP address as a 32- bit number that consists of four sets of numbers separated by periods l These four numbers range from 0 to 255 l A few IP addresses are reserved for special purposes 1

17 IP Address l For example, the IP address is not assigned to any computer on the Internet; it is known as the localhost, and is used to route packets to the local computer l A static IP address is purchased or leased from a large ISP l Because a finite number of IP addresses are available, the IP protocol is being upgraded to a newer version (version 6.0) that can support many more IP addresses 1

18 HTTP Protocol l The HTTP protocol is used to send HTML documents through the Internet l With each packet, the HTTP protocol attaches a header, which contains information such as the name and location of the page being requested, the name and IP address of the remote server that contains the Web page, the IP address of the local client, the HTTP version number, and the URL of the referring page 1

19 HTTP Protocol l It is important to know that HTTP version 1.0 is a stateless protocol l This means that when a client requests a document from the Web server, the server will return the Web page to the client and end all communications with the client l In version HTTP 1.1, the Web server and the client can maintain their connection across Web pages 1

20 TCP/IP Utilities l There are many TCP/IP utility programs that are used to monitor the network l You can use these utilities to perform some basic diagnostic testing on your Web site l If a customer cannot view your Web site, you can use the ping utility to determine whether the Web server is connected to the Internet l Two of the more important TCP/IP utilities include ping and tracert 1

21 Ping l The IP address of the Web site can be found using a TCP/IP utility called ping l Ping is a utility that is used to test network connectivity l When you ping a site, four packets are sent to the IP address l If the Web site is not connected, then a Request Timed Out message appears 1

22 The Ping Utility 1

23 Tracert l Another TCP/IP utility used to locate the Web server is a packet-tracing utility known as tracert l Tracert provides the path that an Internet packet travels to get from the client to a server l When the packet stops at a gateway server, the server determines which path the packet should take next l Tracert lists each stop, or hop, that indicates that the packet has been routed to another server (or router) l The tracert utility can help you detect latencies, or delays, in routing packets to your Web site 1

24 The Tracert Utility 1

25 TCP/IP Client Networking Software l Client for Microsoft Networks is the networking client software used by Windows- based computers l This software may already be installed on your computer l To verify that Client for Microsoft Networks is installed on your Windows 98 or Windows NT computer refer to the procedures outlined on pages 8 and 9 of the textbook 1

26 TCP/IP Client Networking Software l To install Client for Microsoft Networks on your Windows 98 or Windows NT computer continue from previous step as listed on page 9 and 10 1

27 TCP/IP Client Networking Software 1

28 IP Configuration Utilities l The TCP/IP settings, such as the IP address of the client, are assigned using the Network program located in the Control Panel l The Windows operating system provides utilities to detect these TCP/IP settings l Winipcfg is the utility used for Windows 95/98 computers l Ipconfig is the utility used for Windows NT computers 1

29 The Network Dialog Box Identification Tab 1

30 Domain Names l A group of related Web pages, files, and directories—called a Web site—is stored on the Internet on a Web server l A domain name uniquely identifies a single Web site on the Internet (www.visualinterdev.org) l All domain names are registered in a global database known as the registry l In the early 1990’s, Web site sponsors were required to register domain names with InterNIC 1

31 Domain Names l In 1992, InterNIC transferred the domain registration and registry maintenance responsibility to a company called Network Solutions l Network Solutions currently maintains the registry, there are many companies, called registrars, which can register the Web site domain name in the registry database 1

32 Signing Up for a Domain Name l The registrar will have a form to query the database to determine whether your domain name is available l After finding an available domain name, you will need to fill out a request form to register the domain l An administrative, technical, or billing contact who has been previously entered into the database will have an InterNIC handle l The first time you register a domain, your name will be assigned an InterNIC handle; later registrations will only need your InterNIC handle 1

33 Signing Up for a Domain Name l All of the forms will require at least the following information: Domain name (such as course.com) Name, address, and of the registrant Name, address, and of the administrative contact Name, address, and of the technical contact Name, address, and of the billing contact Name and IP address of the primary and secondary DNS servers (the routing servers Billing information for online payment 1

34 Domain Name Service Servers (DNS Servers) l Because a network server can host more than one Web server, the network server needs a means to identify the Web servers on the network l The Domain Name Server (DNS) is a network service that translates domain names to IP addresses l When you register your domain, you do not provide the IP address for your Web site l Instead, you provide the name and IP address of a DNS server 1

35 Domain Name Service Servers (DNS Servers) l The DNS server contains a listing of domain names and their associated IP addresses l The ISP that hosts your Web site will enter your domain name and IP address in their DNS server l When a client requests a Web page, for example, by entering a URL, the client’s network server locates the relevant DNS server, which then provides the relevant IP address 1

36 The Whois Utility l To locate the DNS servers, InterNIC handle, or registrant information for a Web site, you can use the whois utility l The whois utility looks up the information associated with individuals, domain names, and DNS servers in the registry l To locate the registrant, InterNIC handle, and DNS servers of a Web site using the whois utility, follow the instructions on page 13 1

37 The Whois Utility 1

38 The World Wide Web Service l A network server is a network software application that provides network-related services such as , database, messaging, file, and printing services l The network software that stores Web pages and processes the requests for Web pages is called the Web server (sometimes also called the World Wide Web (WWW) Service) l Network administrators can define many Web sites on the same server, and these Web sites are known as virtual Web servers 1

39 The World Wide Web Service l Companies that provide hosting services are called hosting service providers (HSPs) l Some HSPs allow you to have subwebs l Subwebs are subdirectories of a Web site l Internet programming has been referred to as client/server programming because the client application is communicating with the server application l The client communicates with the rest of the Internet via a network server 1

40 The World Wide Web Service l In many instances, the network server is the ISP’s server l The client’s network server routes the request packet to the Web server that contains your Web page l The network server routes the packets back to the client’s browser l The browser receives and processes the request and renders (or displays) the requested Web document 1

41 The World Wide Web Service l Internet applications are no longer limited to a single server l E-commerce Internet applications often communicate with database servers that are not located on the same physical network server as the Web server l In addition to client/server programming, servers communicate with other servers 1

42 Client/Server Programming Using a Web Browser and a Web Server 1

43 Web Servers l Although there are many different types of Web servers, the most common are Apache and Internet Information Server l When working on desktop Windows computers running Windows 98, developers often use Microsoft Personal Web Server to create a Web environment for testing while they are building their Web sites l The Netcraft Web site at Survey/whats/ offers a utility that can detect the type of Web server and operating system a Web site is using 1

44 Hosting Service Providers l After you have selected a domain name and registered it with one of the InterNIC registrars, you will need a service provider to host your Web site l A hosting service provider (HSP) is an ISP that specializes in Web site hosting l HSPs are also called Web presence providers l Some HSPs specialize in working with Internet programmers, while others provide only general Web hosting services 1

45 Hosting Service Providers l Some HSPs offer collocation, whereby they will maintain the equipment connecting the server to the Internet, but the responsibility for maintaining the server software remains with the company l The person who maintains the Web server is called the Webmaster; in small companies where there is no Webmaster, an Internet programmer is often given responsibility for the maintenance of the Web server 1

46 Hosting Criteria l Before searching for an HSP, determine what criteria you will use to evaluate them l Some Web sites on the Internet allow you to search for the features that HSPs often provide l Compiling an evaluation criteria check list will help you find the right HSP for your needs l Some of the questions that will help you evaluate an HSP are listed on pages 16 to 18 of the textbook 1

47 Locating a Hosting Service Provider l There are several lists of HSPs on the Internet l Many of these lists provide a ranking of HSPs based on the features they support, or on feedback by their membership l CNET contains an extensive list of hosting service providers at l The following Web sites contain additional lists of hosting service providers HostIndex - TopHosts.com - The List - 1

48 Internet Programming User Groups l Finally, you should ask colleagues for their opinions about your HSP selections How have other Internet programmers evaluated this HSP? l While an HSP may claim to have 24-hour availability, you might in fact find that they have been prone to network slowdowns and outages l If you do not know any Internet programmers, there are many user groups that can help 1

49 Creating a Web Page l Web pages are created using the HTML language that was established by the HTML protocol l Web pages can be created in a simple text editor program such as Notepad, vi, or BBEdit, or in a Web page editor such as FrontPage or Dreamweaver 1

50 Web Development Tools l In the early days of the Internet, companies usually created disconnected static Web pages; often recreations of their advertising and print materials l Web tools such as HotDog and HTMLPro offered programmers a graphical user interface for creating HTML code l However, as Internet technologies evolved, companies wanted to add interactivity to their pages 1

51 Web Development Tools l To create these more complex Web pages, developers started using Web page editors and Web site management tools to create and maintain Web sites l Some of the common Web development tools are: Microsoft Visual InterDev Microsoft FrontPage Adobe PageMill Allaire HomeSite Macromedia Bare Bones BBEdit for Macintosh 1

52 Web Development Tools l Each of these Web editors can be used to develop small or large Web sites l Most of these vendors also provide additional tools that allow the Internet programmer to create more robust Internet applications l Today, even Microsoft Office allows you to easily create Web pages from within Word, Access, PowerPoint, and Excel 1

53 HTML Tags l HTML is a markup language that uses tags to instruct browsers how to format (or render) the Web page l HTML tags are always enclosed within angle brackets (<>) l Most require a beginning and a closing tag l There are two parts to a Web page The heading section is identified by a pair of head tags ( and ) The body section is identified by a pair of body tags ( and ) 1

54 Tags Used in the Heading Section 1 l Many tags can be used in the heading section of the Web page

55 Tags Used in the Heading Section l The Title Tag l The heading section can contain nested HTML tags, such as the title tag My Home Page l The Meta Tag l The meta tag allows you to provide additional information about the page that is not visible in the browser l The process of loading a new page into the browser is referred to as client-side redirection 1

56 Tags Used in the Body Section l The body section is identified with a pair of body tags ( and ) l The body section of a Web page can contain many HTML tags l Some tags are used to format the characters and paragraphs; other are used to insert images, tables, and forms 1

57 Common HTML Body Tags 1

58 HTML Tab Attributes l Within many HTML tags, you can specify additional attributes l These attributes provide a means of altering the tag in some way l For example, the paragraph tag allows you to insert a paragraph l The align property of the paragraph tag allows you to align the paragraph to left, right, or center or to justify it 1

59 Creating a Basic Web Page Using HTML l The following is an example of a basic Web page named storehome.htm, which was created in Notepad Store Home Home Page Welcome to our store! 1

60 Other HTML Tags l The body tag, which is used to identify the body section, can be modified using several attributes l The image tag is used to insert images l The anchor tag is used to insert hyperlinks to other pages or Web sites l The form tag is used to insert a form 1

61 The Body Tag l The body tag is used to alter the format of the entire document l The body tag contains several attributes l The body tag contains an attribute called bgColor that allows the programmer to change the color of the background l The background property of the body tag can be used to identify a background image for the Web page 1

62 List Tags l Lists can be formatted using the unordered list tag, the ordered list tag, or the definitions list tag l The list items contain nested italic tags, which are used to format the text within the list item tag (as shown at the bottom of page 24 of the textbook) 1

63 Other HTML Tags l The Image Tag l The image tag is used to add a graphic image to the Web page l The Anchor Tag l The anchor tag is most often used to create a hyperlink to another document l You can force the browser to open the Web page in a new window by specifying the target window l The target window can also be identified in the URL l You can use the anchor tag to create a bookmark, which is used to specify a location, within a Web page 1

64 Attributes of the Image Tag 1

65 The Table Tag l The table tag is used to create a table on a Web page l The border property of the table tag is used to create a border around all of the cells in the table l The width property of the table tag can be used to specify the width of the table either in pixels or by percentage of the browser window 1

66 The Form Tag l Forms are used to receive information from the user l Forms are commonly used to allow users to register on a Web site, to log in to a Web site, to order a product, and to send feedback l The action attribute identifies the program or script that will process the form l The method attribute of the form tag is used to identify how the form field names and values will be sent to the server 1

67 Form-Related Tags 1

68 The Input Tag Attributes l The input tag creates a form element that can retrieve information l The type attribute identifies the format of the input tag l The value attribute provides a default value for the input tag l Additional attributes are available with the various types of input elements 1

69 Additional Resources l Additional Internet resources, which include online tutorials that cover HTML tags and their properties, can be found at Life Beyond Yahoo (http://www.lifebeyondyahoo.com/) at asp 1 3

70 Publishing Your Web Page l Some Web development tools, including FrontPage, InterDev, and Dreamweaver, allow you to publish Web pages directly to a Web server l However, if you are using a text editor, you will need a program to copy your files to the Web server l You can use FTP software to transfer your files from your client computer to the Web server 1

71 Summary l The early Internet was called ARPANET and was used by the government and universities for research and education l The Internet uses TCP/IP to route and deliver packets from one computer to another l The ping utility tests network connectivity l The tracert utility can detect whether a Web site is slow, or disconnected from the Internet 1

72 Summary l You can create Web pages using text editors or Web page editors l HTML documents consists of a heading section and a body section, identified by the head and body tags l Personal Web Server (PWS) is available free from Microsoft and allows you to develop and test your Web pages locally l There are many resources available online for learning how to create basic Web pages using HTML 1


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