11 Web Technology 12 Web Technology <A HREF> tag specifies the information necessary to display the links that allow you to jump to related Web pages

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1 2 Web Technology The Internet is a communications network The contents of Web pages are another type of data that is carried over the Internet The Web is an interlinked collection of information that flows over the Internet 3 Web Technology Two of the most important elements of the web Hypertext Transfer Protocol (HTTP) Hypertext Markup Language (HTML) Hypertext text linked together in non-linear form Hypertext link clickable text that lets you access related documents 4 Web Technology 5 Web Technology Web pages are written in HTML HTML document plain text, or ASCII, document with embedded HTML tags HTTP communications protocol is used by web browser when requesting specific pages 6 Web Technology 7 Web Technology HTML (Hypertext Markup Language) is a set of specifications for creating documents HTML tags specify how the document should appear when displayed World Wide Web Consortium (W3C) organization that reviews and revises HTML standard HTML 3.2 in early 1997, 4.0 in late 1997, 4.01, in Web Technology HTML tags, such as <HR> and <B>, are enclosed in documents Treated as instructions to the browser <HR> creates a horizontal rule <B>Caterpillars</B> love sugar <B>,</B> make the word Caterpillars bold Is not case-sensitivesensitive (<b> is same thing as <B>) 9 Web Technology 10 Web Technology

2 11 Web Technology 12 Web Technology <A HREF> tag specifies the information necessary to display the links that allow you to jump to related Web pages 13 Web Technology 14 Web Technology HTML document is like a screenplay Web browser is like a director Web page exists only for the duration of the performance 15 Web Technology Your browser can display the source of a Web page when you select the appropriate menu option in your browser View, Source in Internet Explorer 16 Web Technology 17 Web Technology Formatting tags change the appearance of text Link tags specify where and how to display links Media tags specify how to display media elements Operational tags specify the basic setup for a Web page 18 Web Technology 19 Web Technology Browser plays two roles: Uses HTTP to send messages to a Web Server Interprets the HTML tags in order to display the requested Web page 20 Web Technology Mosaic one of earliest graphical browsers Netscape Navigator Internet Explorer (IE) Included with Microsoft Windows 98 OS and higher Opera one of few alternatives to IE and Netscape 21 Web Technology Usually, it is a good idea to upgrade when a new version comes out Contain up-to-date functionality Some Web pages depend on new HTML features supported by newer versions of a browser

3 Browser interprets HTML Files that are not handled by the browser; sometimes require you to download helper application, plug-in, or player in order to handle the files 23 Web Technology Helper application program that understands how to work with a specific file format Updates your system so browser can automatically open helper application that works with a specific file format Used by browser to open non-html file format 24 Web Technology Plug-in displays files within the browser window Helper application displays files in new window Distinction is disappearing as Web development continues Player any helper application or plug-in that helps a browser display a particular file format 25 Web Technology Netscape provides a list IE doesn t provide a list, but you can see the list in the Control Panel s Add/Remove Programs icon 26 Web Technology 27 Web Technology HTTP (Hypertext Transfer Protocol) works in conjunction with TCP/IP to get Web resources to your desktop Has commands or methods that help your web browser communicate with server Transports your request to server and back Socket represents one end of a connection Opened by web browser and connected to web server 28 Web Technology 29 Web Technology Yes. HTTP is classified as a stateless protocol One request and response per session Assembly of one page requires one request per element on the page 30 Web Technology HTTP status code indicates whether or not the browser s request could be fulfilled 200 request fulfilled

4 32 Web Technology Web server is configured to include HTTP software Always running when server is up and ready to fulfill requests One port is dedicated to listening for HTTP requests 33 Web Technology Server mayhave other software, and, for efficiency, devotes one port for HTTP requests, one port for FTP, and one port for Logical port created by communications software and uses provided Internet hardware Port 80 HTTP Port 25 SMTP Port 21 FTP 34 Web Technology 35 Web Technology A single port can connect to many sockets at a time Depends on server s memory and operating system (at a minimum hundreds of requests) Server farm group of multiple servers that handle thousands of requests that come in each second 36 Web Technology Not necessarily server can house many sites or just one, and one site may cover several servers (if it is very large) housed on several identicallyconfiguredconfigured file servers 37 Web Technology Cookie small chunk of data generated by a Web server and stored in a text file on your computer Cookie: jqstudent@sarasota.fl.us/ SITESERVER ID= d2390f3b8639aa3c7cf1ca8f5 sarasota.fl.us / Web Technology Web sites use cookies to: Track your path through a site Provide information thatallowsallows the Web site to present you with ad banners Retain anypersonal information that you type into a Web page form 39 Web Technology Because each request is considered separate by the Web server Cookies allow server to know which requests are yours

5 Cookies are a relatively safe technology Data, notcomputer program Can only be accessed by site that created it Contain only information you disclose while using the site Uses a randomly generated number instead of your name 41 Web Technology Most browsers will let you block cookies, but for many Web sites, cookies are only mechanism for tracking your activity or remembering purchases Without cookies, you maynotbe able to do some things on the Web P3P (Platform for PrivacyPreferencesPreferences Project) defined security tags for cookies in their HTTP header Compact Privacy Policy describes how cookie is used by Web site 42 Web Technology 43 Web Technology A web programmer can program cookie to time out You can delete the cookies Netscape uses Cookies.txt or Magiccookie IE stores each in separate file 44 Web Technology 45 Web Pages, Web Sites, And E-Commerce 46 Basic Web Page Authoring Text editor most difficult as you have to create everything from scratch 47 Basic Web Page Authoring Conversion option available in many software applications Microsoft Word File menu s Save As Web Page Online Web authoring tools Provided by some ISPs Type, select, drag, and drop elements onto Web page 48 Basic Web Page Authoring Web authoring software provides tools for creating web pages Microsoft FrontPage 49 Basic Web Page Authoring Head section begins with <Head> and contains: Title of your page as it will appear in the title bar of your browser window Global formatting information Information about your page that can be used by search engines Scripts that add interactivity to your page

6 HTML tags that format the text Varietyof links (including graphics and sounds ) Web page header subtitle that appears in a font that is different style than normal text 51 Basic Web Page Authoring 52 Basic Web Page Authoring A style is the same as in the world of word processing Bold, italic, green, and Arial Don t get carried away, choose base font for paragraphs; consistent style for headers 53 Basic Web Page Authoring In web page authoring software, highlight and then format With a text editor, use tags such as: 54 Basic Web Page Authoring Cascading style sheet (CSS) acts as a template that can control the layout and design of Web pages Internal placed near the beginning of html document (<style> tag within <head> section) External style sheet contains formatting specifications for a group of Web pages; a separate file contains the styles 55 Basic Web Page Authoring <IMG SRC> tags <IMG SRC = truck.gif > Indicates the filename of the graphics to display (truck.gif) In FrontPage, you can just insert the image as in a word processor, and it will create the <IMG SRC> tag and then save the picture reference for you automatically 56 Basic Web Page Authoring 57 Basic Web Page Authoring Most graphics are stored in GIF (Graphics Interchange format) best format for non-photographic images JPEG (Joint Photographics Experts Group) best for photographic-quality images PNG (Portable Network Graphics) alternative graphics format instead of gifor jpeg 58 Basic Web Page Authoring Animated GIF graphic file that consists of a sequence of frames or related images

7 Depends on your ability to manipulate an image so that it has the right dimensions to balance other elements on the page 61 Basic Web Page Authoring A link appears as underlined, blue text (color depends upon settings) Can also be a button or a graphic The HTML has two parts Destination, Label 62 Basic Web Page Authoring Instead of text label, you can use an image as a clickable link Can connect to graphics or other Web pages Can look like buttons, complete with labels and icons 63 Basic Web Page Authoring Internal link links to other pages on same site External link links to pages outside of the site Interpage link jumps to a location within same page mailto link automatically opens pre-addressed form that can be filled in and sent 64 Basic Web Page Authoring Image map clickable map, photo, or diagram Hot spot links within the image map Can be created by text editor Web authoring software MapEdit 65 Basic Web Page Authoring Broken link non-functioning link Can occur if webmaster moves requested file, deletes it, or changes its name 404 Page Not Found Broken link icon 66 Basic Web Page Authoring Web page table is grid of cells that can be used as a layout tool for specifying the placement of text and graphics on a page Important as HTML does not include a formatting feature for multiple columns 67 Basic Web Page Authoring 68 Basic Web Page Authoring Cells can contain text or graphics, but all the cells do not have to be the same size Tables are a flexible layout tool

8 To view table, must preview page using your browser 70 Basic Web Page Authoring HTML frame is a part of a Web page that scrolls independently of other parts of the page Are separate windows appearing in the browser s display area Can display multiple documents at once Until HTML 4.0 in 1997, some browsers did not support frames and somesites sites include no frames versions of their pages Sometimes misused 71 Basic Web Page Authoring 72 Basic Web Page Authoring Can only remove frames if Web page designers have included that in their design Way around it: connecting to the page that you want by directly entering the URL 73 Basic Web Page Authoring 1. Test each page locally 2. Transfer pages to a Web server 3. Test all links 4. Update your site to keep it current 74 Web Pages, Web Sites, And E-Commerce 75 Web Page Extensions, Scripts, and Programs DHTML (Dynamic HTML) combination of HTML tags, cascading style sheets, and scripts that allow authors to animate the pages they create Allow page to change its appearance after itisis loaded by the web browser, without requests to the server 76 Web Page Extensions, Scripts, and Programs 77 Web Page Extensions, Scripts, and Programs No, DHTML is just a term that is used to describe a method for using HTML in combination with a few other technologies 78 Web Page Extensions, Scripts, and Programs All Web browsers support DHTML, but each browser supports DHTML somewhat differently Message - This site is best when viewed with Netscape 79 Web Page Extensions, Scripts, and Programs

9 80 Web Page Extensions, Scripts, and Programs Individual users and groups of users can create their own tags DTD files (Document Type Definition files) contain the tags used in an XML file XML parser tool for reading XML documents 81 Web Page Extensions, Scripts, and Programs XLS (extensible Stylesheet Language) creates customized tags that control the display of the data that s contained in an XML document 82 Web Page Extensions, Scripts, and Programs XHTML is the follow-up version to HTML 4 W3C called it XHTML instead of HTML 5 Includes all of HTML 4 tags, but can be extended by addition of customized tags 83 Web Page Extensions, Scripts, and Programs Allow to perform complicated tasks and respond to user actions Script allow designer to embed simple program instructions (scripting statements) 84 Web Page Extensions, Scripts, and Programs Scripting languages allow pages to become more interactive Allows e-commerce sites to verify credit card information Makes interactive pages like loan payment calculators 85 Web Page Extensions, Scripts, and Programs JavaScript VBScript Alternatives PerlScript Python REXX Awk 86 Web Page Extensions, Scripts, and Programs Client-side scripts consist of scripting statements embedded in HTML document Execute in browser on client Server-side scripts consist of statements that are executed on server Typically acceptdata submitted by a form 87 Web Page Extensions, Scripts, and Programs 88 Web Page Extensions, Scripts, and Programs

10 89 Web Page Extensions, Scripts, and Programs Java high-level programming language developed by Sun Microsystems Small Java applications are called Java applets Input forms, rotating images, interactive animation 90 Web Page Extensions, Scripts, and Programs Stored in file with.java filename extension Bytecode compiled source code Uses <APPLET> HTML tag Java Virtual Machine (JVM) browser built-inin feature to execute applets 91 Web Page Extensions, Scripts, and Programs 92 Web Page Extensions, Scripts, and Programs 93 Web Page Extensions, Scripts, and Programs Applets have the following restrictions: Are not allowed to open, modify, delete or create files on your computer Are not allowed to make any network connections exceptto to the originating site Are not allowed to start other programs Sometimes they are blocked by network firewalls Security Exception error message 94 Web Page Extensions, Scripts, and Programs ActiveX control compiled computer program that can be referenced from within an HTML document Can be used on client-side or server-sideside 95 Web Page Extensions, Scripts, and Programs 96 Web Page Extensions, Scripts, and Programs Installed on your computer s hard disk, whereas Java applets are simply downloaded into memory and run Java applets work on many computer platforms, but ActiveX controls are designed only for the Windows platform using the Internet Explorer browser 97 Web Page Extensions, Scripts, and Programs Most are safe, but ActiveX controls are full-fledgedfledged programs Can include routines that alter or delete data on your computer s hard disk You can modify IE so that it never downloads any ActiveX controls 98 Web Page Extensions, Scripts, and Programs 99 Web Page Extensions, Scripts, and Programs Digital certificate electronic attachment to a file that verifies the identity of

11 If your security is set to medium, browser displays a warning message to alert you that an ActiveX component is trying to install itself Your browser reads the certificate, displays the name of the person or company that signed it, and verifies that the component was not altered since it was signed 101 Web Page Extensions, Scripts, and Programs 102 Web Pages, Web Sites, And E-Commerce 103 E-Commerce E-commerce describes financial transactions that are conducted over a computer network Includes physical products, digital products, and services Digital products such as News, music, video, databases, software, and all types of knowledge-based items Peddle services, such as arranging trips, online medical consultation, and remote education Carried out by computer or require human agents 104 E-Commerce Demographics not yet stabilized In 1995, 30-something white male Now, females and teens have entered the online shopping frayin droves B2C (business-to-consumer) e-commerce typical e-commerce activities thatthethe typical Web surfer enjoys C2C (consumer-to-consumer) includes online auctions and rummage sales 105 E-Commerce B2B (business-to-business) e-commerce involves one enterprise buying goods and services from another enterprise B2G (business-to-government) e-commerce aims to help businesses sell to governments 106 E-Commerce 107 E-Commerce 108 E-Commerce Customers can easily search through large catalogs Can configure products online Can see actual prices Can build an order over several days Allows merchants to attract customers Global market Can track customer preferences and produce individually tailored marketing

12 pay for it 109 E-Commerce 110 E-Commerce 111 E-Commerce 112 E-Commerce 113 E-Commerce 114 E-Commerce 115 E-Commerce 116 E-Commerce 117 E-Commerce 118 E-Commerce Shopping cart cyberspace version of the good old metal cart that you wheel around a store and fill up with merchandise Shopper browses Web site, and then adds products using a Buy or Add to Cart button Uses cookies to store information about your activities on Web site HTML form an on-screen form created using <FORM> and <INPUT> tags Allows you to enter data for payment and shipping information Your information is stored on your hard disk; it not left hanging around When you click a Submit button, information is gathered and submitted via a specially designated program on an HTTP server Packet sniffer monitors data as it travels over networks 2 technologies protect the data SSL (Secure Sockets Layer) encrypts the data S-HTTP (secure HTTP) extension of HTML thatencrypts the text of an HTTP message before it is sent Securing your credit card number solves only half of the security problem SET (Secure Electronic Transaction security method that relies on cryptography and digital certificates to ensure that transactions are legitimate as well as secure Endorsed by major players in the e-commerce arena CGI (Common Gateway Interface) set of specifications or standards for how servers can handle a variety of HTTP requests ASP (Active Server Pages) server-sideside technology developed by Microsoft that offers an alternative to CGI

13 119 E-Commerce 120 E-Commerce 121 E-Commerce 122 E-Commerce 123 E-Commerce 124 E-Commerce 125 E-Commerce Fake Storefronts Trojan horse site Intercepted packets uses packet sniffers Database break-ins unauthorized access of customer databases Dishonest employees Always-on connections Only foolproof method don t use it To reduce probability of online credit card fraud, make sure that you deal with legitimate merchants One-time-use credit card numbers allow customers to make purchases while keeping their actual card numbers hidden Provided by your credit card provider s Web site Electronic wallet (digital wallet) software that stores and handles the information that a customer typically submits when finalizing an e-commerce purchase Are created by subscribing at the wallet provider s site Pops up whenever you make a purchase at a participating merchant s site Data can be stored on your computer or on a server maintained by a wallet provider Server-side wallets are called thin wallets because theydon t require much storage space on your computer Requires client-side and server-sideside software Browser plug-in on client-side Server-side resides on an HTTP server maintained by the merchant Data is transported over secure connection, such as SSL Data is stored in an encrypted format Even if hacker gains access, the data that it contains will be difficult to decode Can only be opened if you provide the correct password (acts like a PIN number) to prevent unauthorized access Person-to-person payment offers alternative to credit cards PayPal

14 127 E-Commerce 128 E-Commerce Advantage only payment service sees your credit card numbers Still in its infancy, and companies are still scrambling to offer reliable, long- term service to customers Unregulated Sometimes go out of business without providing notice Consumer advocates recommend using these services with caution, and keeping account balances low

STUDY GUIDE CHAPTER 7

STUDY GUIDE CHAPTER 7 True/False Indicate whether the statement is true or false. 1. Every Web page has a unique address called a(n) Uniform Resource Locator. 2. Web 3.0 refers to innovations like cloud