World Wide Web Basics

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1 Chapter-1 Introduction World Wide Web Technologies GROUP OF INSTITUTIONS © ITS Mohan Nagar Gzb prepared by Umang Singh

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2 Topics to be covered in Chapter -1 • About Internet • About WWW • Comparison between Internet and WWW • Storing locating and transmitting information on the Web • Accessing information on the web • External data in HTML documents • Problems with file-based Web sites • Web Page • Exercises • Summary • Conclusion • Test Your Self © ITS Mohan Nagar Gzb prepared by Umang Singh

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3 Basic Terminology1 About Internet • The Internet is a massive network of networks a networking infrastructure. • It connects millions of computers together globally forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. • Information that travels over the Internet does so via a variety of languages known as protocols. © ITS Mohan Nagar Gzb prepared by Umang Singh

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4 Basic Terminology1 About Internet © ITS Mohan Nagar Gzb prepared by Umang Singh Web Browser Client http://www.itsgzb.ac.in/index.html Web Server Server www.itsgzb.ac.in index.html Internet or Intranet Fig. 1: Internet

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5 Basic Terminology1Cont’d.. © ITS Mohan Nagar Gzb prepared by Umang Singh How Big Is the Internet

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6 Basic Terminology2 About WWW • The World Wide Web or simply Web is a way of accessing information over the medium of the Internet. • It is an information-sharing model that is built on top of the Internet. • The Web uses the HTTP protocol only one of the languages spoken over the Internet to transmit data. • Web Services which use HTTP to allow applications to communicate in order to exchange business logic use the the Web to share information. • The Web also utilizes browsers such as Internet Explorer or Firefox to access Web documents called Web pages that are linked to each other via hyperlinks. © ITS Mohan Nagar Gzb prepared by Umang Singh

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7 Basic Terminology2Cont’d.. About WWW Cont’d.. • Web documents also contain graphics sounds text and video. • The Web is just one of the ways that information can be disseminated over the Internet. • The Internet not the Web is also used for e-mail which relies on SMTP Usenet news groups instant messaging and FTP. • So the Web is just a portion of the Internet albeit a large portion but the two terms are not synonymous and should not be confused © ITS Mohan Nagar Gzb prepared by Umang Singh

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8 Remember it The Web is not the Internet • The Internet is everything that happens using a packet- switched network of computers. • The World Wide Web is one particular family of protocols and applications which use the Internet. How many people use the Internet World Total 407.1 million © ITS Mohan Nagar Gzb prepared by Umang Singh

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9 Storing locating and transmitting information on the Web How information is located: the URL  To move from one page of a document to another page or to another document on the same or another Web site the user clicks a hyperlink usually just called a link in the document shown in their Web client.  Documents and locations within documents are identified by an address defined as a Uniform Resource Locator or URL. The following URL illustrates the general form: http://www.sybase.com/productsl or http://www.sybase.com/inc/corpinfo/mkcreate.html © ITS Mohan Nagar Gzb prepared by Umang Singh

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10 Each page of information on the web has a unique address called the URL at which it can be found. http://faculty.uscupstate.edu/atzacheva/lecture1.html The document can be obtained using the Hypertext Transfer Protocol HTTP Host Name - The Name of Web Server Path to the Web Page Denotes that the File is Written in HTML HyperText Markup Language File Name 1 2 3 Protocol Host Name File Name The Universal Resource Locator URL © ITS Mohan Nagar Gzb prepared by Umang Singh

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11 Storing locating and transmitting information on the Web Cont’d.. • URLs contain information about which server the document is on and may also specify a particular document available to that server and even a position within the document. • In addition a URL may carry other information from a Web client to a Web server including the values entered into fields in an HTML form. • For more information about URLs and addresses on the Web see the material available at the following address: http://www.w3.org/pub/WWW/Addressing/ • When a user clicks a link on a document on their Web client the URL is sent to the server of the indicated Web site. The Web server locates the document and sends the HTML to the Web client across the network. © ITS Mohan Nagar Gzb prepared by Umang Singh

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12 Accessing information on the web As Figure 1 illustrates information is stored at Web sites. Access to the information is managed by a Web server for the site. Users access the information using Web clients which are also called browsers. © ITS Mohan Nagar Gzb prepared by Umang Singh Figure 1: Accessing information on the Web Browser is designed to display the pages of information located at Web sites around the world.

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13 Accessing information on the web • Information on the Web is stored in documents using a language called HTML HyperText Markup Language. • Web clients must interpret HTML to be able to display the documents to a user. • The protocol that governs the exchange of information between the Web server and Web client is named HTTP HyperText Transfer Protocol. © ITS Mohan Nagar Gzb prepared by Umang Singh

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14 About HTTP • The standard Web transfer protocol is HTTP HyperText Transfer Protocols. • It is used for document exchange between servers and clients typically browsers in the WWW. • To retrieve a document the client first sends a request to the web server and waits for a reply • An HTTP service a program that waits for http requests on the server then handles the request and the document is sent to the client over a connection established using TCP/IP – Transmission Control Protocol / Internet Protocol © ITS Mohan Nagar Gzb prepared by Umang Singh

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15 About HTML • Programming Language • Used to create web pages • Use Hypertext documents for use on WWW. © ITS Mohan Nagar Gzb prepared by Umang Singh

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16 External data in HTML documents • HTML documents can include graphics or other types of data by referencing an external file for example a GIF or JPEG file for a graphic. • Not all these external formats are supported by all Web clients. • When the document contains such data the Web client can send a request to the Web server to provide the relevant graphic. • If the Web client does not support the format it does not request the information from the server. © ITS Mohan Nagar Gzb prepared by Umang Singh

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17 Problems with file-based Web sites • In a file-based Web site each resource is a separate file. For large Web sites this leads to management problems. • For example maintaining current copies of hundreds or thousands of different resources in separate files is difficult enough maintaining the links between these resources is even more challenging. • Another problem is that many Web sites contain information that is dynamic--pricing information for example or employee information on an organizations intranet. © ITS Mohan Nagar Gzb prepared by Umang Singh

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18 Problems with file-based Web sites • Maintaining such information in HTML files in addition to the database where it resides is a huge task. • For these and other reasons linking databases to the Web is increasingly the solution of choice for management of large Web sites and management of dynamic content. • Database storage of Web information can either replace or complement file storage of Web resources. © ITS Mohan Nagar Gzb prepared by Umang Singh

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19 About Webpage A webpage or web page is a document or resource of information that is suitable for the World Wide Web and can be accessed through a web browser and displayed on a computer screen © ITS Mohan Nagar Gzb prepared by Umang Singh

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20 Other Common Languages • DHTML • ASP • JavaScript • XML © ITS Mohan Nagar Gzb prepared by Umang Singh

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21 Technicalities like Firewalls CGI Database Networking • A Firewall is a system or group of systems that enforces as access control policy between two or more networks. • CGI is a standard for interfacing external applications with information servers such as HTTP or Web Servers. • Database • Photoshop is a widely used image editing application from Adobe often used as a benchmark for other imaging applications. • Graphics animation audio and video present on the web. © ITS Mohan Nagar Gzb prepared by Umang Singh

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22 Remember it • Modem : “electronic device that converts computer signals into an analog signal in order to transmit data over a telephone line”. • Router: “It determines the nest network point to which a data packet should be forwarded enroute toward its destination.” • Server: “A server is a computer that handles requests for data email file transfers and other network services from other computers clients”. • Web Server : A computer that is permanently connected to the Internet and allows people to read web pages located on that computer is called a web server. © ITS Mohan Nagar Gzb prepared by Umang Singh

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23 Remember it • Favicon : it is a custom icon that appears next to website’s URL in the address bar of a web browser. • Java: It is pre OOP which is used on web pages for interactivity. • Java Script: It allows things like popups popunders and interactive elements on a webpage. • Cookie: It keeps track of user preferences limit exposure of intrusive ads or keep track of login and password information for certain websites. • Hyperlink or link: It is an embedded html code that allows an Internet user go from webpage to webpage and website to website. © ITS Mohan Nagar Gzb prepared by Umang Singh

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24 Web Protocols • TCP: Transmission of data from an application to the network. It breaks data down into IP packets before they are sent and for assembling the packets when they arrive. • IP : Internet Protocol: Communication with other computers. IP is responsible for the sending and receiving data packets over the Internet. • HTTP: takes care of the communication between a web server and a web browser. HTTP is used for sending requests from a web client a browser to a web server returning web content web pages from the server back to the client. • HTTPS: takes care of secure communication between a web server and a web browser. HTTPS typically handles credit card transactions and other sensitive data. © ITS Mohan Nagar Gzb prepared by Umang Singh

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25 Web Protocols • FTP File Transfer Protocol: a standard Internet protocol is the simplest way to exchange files between computers on the Internet. • SMTP: SMTP is generally used to send messages from a mail client to a mail server. • POP: Protocol used to retrieve e-mail from a mail server. Most e-mail applications use the POP protocol. © ITS Mohan Nagar Gzb prepared by Umang Singh

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26 Self Assessment Questions • A ________________ is a system or group of systems that enforces an access control policy between two or more networks. • ______ is full form of URL. • _______ is used primarily as a tool to efficiently uploading and downloading files on the internet • The full form of HTML is ______ • __________ is a widely used image editing application from adobe. • What is the difference between Internet and WWW. © ITS Mohan Nagar Gzb prepared by Umang Singh

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27 Assignment-1 Q.1 Attempt all Questions: i What is the difference between FTP and HTTP ii Write a short note on the various terms used on the web and what they mean iii What is IP address iv What is TCP/IP Model © ITS Mohan Nagar Gzb prepared by Umang Singh

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