Chapter 22 Browsing The World Wide Web Introduction

Chapter 22 - Browsing The World Wide Web • Introduction • Description Of Functionality – Obtain textual information, recorded sounds, or graphical images from a variety of sources on remote computers as requested. – Display the retrieved information automatically. – Store a copy of retrieved information on disk. – Print a copy of retrieved information on paper. – Follow a reference found in a document to related documents, possibly on different computers. • Browsing vs. Information Retrieval – Although they transfer data efficiently, information retrieval services such as FTP do not display the contents of documents for users.

Chapter 22 - Browsing The World Wide Web – A browsing service permits users to view information from remote computers without knowing the names of files. After obtaining a copy of a document from a remote computer, the browsing service automatically displays the contents, and allows the user to select related documents. • Early Browsing Services Used Menus[Gopher] – A menu-driven browsing system displays a menu of choices for a user. By selecting an item from the menu, the user can request the browsing service to retrieve information from a file or retrieve another menu.

Chapter 22 - Browsing The World Wide Web • A Menu Item Can Point To Another Computer – A browsing system hides computer boundaries completely, and makes information on a a large set of computers appear to be part of a single, integrated system. A browser can jump from one computer to another without a user knowing or caring about which computers are being accessed. • How a Browser Works • An Example Point-and-Click Interface • Combining Menu Items With Text

Chapter 22 - Browsing The World Wide Web • The Importance of Integrated Menus – Curent browsing services embed menu items in other information, eliminating ambiguities and making it easier to understand each item, combining menu items with other information encourages a user to explore items as they are encountered. • Menus Embedded In Text Are Called Hypertext – Although documents in a hypertext system can contain a complex maze of references, the complexity may not be obvious to a user who can view only one document at a time. • Multimedia

Chapter 22 - Browsing The World Wide Web • Video And Audio References Can Be Embedded In Text – A hypermedia system can embed references to nontextual information as well as references to textual information in a document. – If the user selects a reference to a document, the hypermedia system displays the document: if the user selects a nontextual reference, the hypermedia system plays the audio or displays the images. • The World Wide Web – In addition to containing textual information, World Wide Web documents can contain sounds and graphical images. To display nontextual information, a computer must have multimedia hardware

Chapter 22 - Browsing The World Wide Web • Browser Software Used To Access The Web – A Web browser consists of a program that provides access to hypermedia documents on the World Wide Web. A Web browser displays a given document, and allows the user to select among highlighted items, which can consist of either text, graphics, or sound. • • An Example Hypermedia Display Control Of The Browser External References Recording The Location Of Information – A Uniform Resource Locator consists of a short character string that identifies a particular multimedia document. Given a valid URL, a browser can go directly to the page without passing through other documents.

Chapter 22 - Browsing The World Wide Web • Bookmarks • How The World Wide Web Works • A URL Tells A Browser Which Computer To Contact • A URL Tells A Browser Which Server To Contact – Each URL uniquely identifies a page of information by giving the name of a remote computer, a server on that computer, and a specific page of information available from the server. • Use Of The Name WWW In URLs • A Browser Provides Access To Multiple Services

Chapter 22 - Browsing The World Wide Web • Inside A Browser Program – A browser's novelty and power arise becasue it integrates access to multiple Internet services into a single, seamless browsing system. The browser uses information in the URL to automatically select an access mechanism from among such services as remote login, file transfer, and gopher. • Getting Started With A Browser • Summary • An Observation About Hypermedia Browsing

Chapter 22 - Browsing The World Wide Web • Terms – – – bookmark browser browsing hypermedia hypertext information browsing service menu point-and-click interface selectable item Uniform Resource Locator (URL) World Wide Web (WWW)