Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques1 Topic 1 - Introduction to the Internet, Web, and Web browsers Outline 1 History of the Internet 2 The Internet today 3 Host Machines and Host Names 4 The Client/Server Software Model 5 Personal Computing 6 The World Wide Web 7 Web Browsers 8 Searching the Internet

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques2 History of the Internet ARPAnet Implemented in late 1960’s by ARPA (Advanced Research Projects Agency of DoD) Networked computer systems of a dozen universities and institutions with 56Kbps communications lines Grandparent of today’s Internet Intended to allow computers to be shared Became clear that key benefit was allowing fast communication between researchers – electronic- mail ( )

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques3 History of the Internet ARPA’s goals Allow multiple users to send and receive info at same time Network operated packet switching technique Digital data sent in small packages called packets Packets contained data, address info, error-control info and sequencing info Greatly reduced transmission costs of dedicated communications lines Network designed to be operated without centralized control If portion of network fails, remaining portions still able to route packets

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques4 History of the Internet Transmission Control Protocol (TCP) Name of protocols for communicating over ARPAnet Ensured that messages were properly routed and that they arrived intact Organizations implemented own networks Used both for intra-organization and communication

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques5 History of the Internet Huge variety of networking hardware and software appeared ARPA achieved inter-communication between all platforms with development of the IP Internetworking Protocol Current architecture of Internet Combined set of protocols called TCP/IP The Internet Limited to universities and research institutions Military became big user Next, government decided to access Internet for commercial purposes

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques6 History of the Internet Internet traffic grew Businesses spent heavily to improve Internet Better service their clients Fierce competition among communications carriers and hardware and software suppliers Result Bandwidth (info carrying capacity) of Internet increased tremendously Costs plummeted

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques7 The Internet is a network of networks that are spread all over the world Networks that are geographically close are called Local Area Networks (LANs) Often in the same building The university’s network is a prime example The Internet is a largely heterarchical network containing many individual LANs A heterarchical network contains many nodes that are interconnected. A hierarchical network contains a tree-like structure where some nodes are superior to others. The Internet today

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques8 The Internet today

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques9 A characteristic of a heterarchical network is that it is a robust network. If some nodes are removed, data can still be sent between nodes Hierarchical networks do not lend themselves to robustness The Internet also has dynamic routing, where the route of the data is determined at the time of transmission based on current network conditions. The Internet today

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques10 The Internet today How big is the Internet? Number of networks Number of servers Number of domain hosts Number of (indexed) web pages / web sites Usage statistics Number of countries Amount of stored information What about the Deep Web?

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques11 Each computer on the Internet is a host machine. Each computer has a unique Internet Protocol (IP) address, such as Some computers have a permanent IP address Some computers borrow an IP address while they are connected to the Internet An IP address is not human-friendly Host Machines and Host Names

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques12 The IP address for most host machines are mapped to a Domain Name Service (DNS) address in order to be more people-friendly The DNS address consists of a host name followed by a domain name Example DNS Address: mail.yahoo.com Host Name is: mail Domain Name is: yahoo.com Host Machines and Host Names

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques13 Each domain name consists of: Institutional site name Top Level Domain name (TLD) Example: cse.fau.edu cse.fau is the Dept. of Computer Science and Engineering at Florida Atlantic University edu refers to an educational site Host Machines and Host Names

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques14 Examples of TLDs include:.coma commercial organization.edua US educational site.neta network site.auAustralia.frFrance.hkHong Kong.esSpain... (many others) Host Machines and Host Names

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques15 New TLDs have been added as the original set became overloaded While each machine has a unique IP address, it can have multiple DNS addresses (called aliases) Anyone can register a DNS address When you type in a DNS address, a domain name server translates it into an IP address. Host Machines and Host Names

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques16 Clients and servers are host machines A client is the host machine that requests information from the server The server is a resource that provides a service for (many) clients The client/server interaction is the foundation for all Internet communication The Client/Server Software Model

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques17 The Client/Server Software Model

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques18 Some companies use servers that do not need to be installed on the client to supply commercial software to clients Application Service Providers (ASPs) provide software through subscriptions The software is “rented” with this arrangement The Client/Server Software Model

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques19 Personal Computing IBM 1981, introduced IBM Personal Computer Made personal computing legitimate in business, industry and government organizations Computers were “stand-alone” units Info only shared between computers through exchange of discs Machines could be linked Over telephone lines Over Local Area Networks (LANs) Led to distributed computing

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques20 Personal Computing Computers today As powerful as million dollar machines from 20 years ago Workstations Most powerful desktops today Provide users with enormous capabilities Information easily shared over networks Networks controlled by servers Common programs and data used by client computers Popular operating systems UNIX, MacOS, Windows XP, Linux Portable devices (PDAs, tablet PCs, cell phones) with great computing power

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques21 The World Wide Web (WWW or Web) has become a popular means of accessing information and services. The Web allows computer users to easily locate and view multimedia-based documents. Introduced in 1990 by Tim Berners-Lee The Web and the Internet (Net) are not the same. A Web browser is the software necessary to view information. Some browsers are integrated into other software, such as an client. The World Wide Web

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques22 Navigating the Web only takes a few commands. The information in the Web is organized as hypertext, graphics, video, and sound The text in a Web page may contain hyperlinks that, if clicked, allows you to view related information on other Web pages. You control where you go and what information you see via these hyperlinks The World Wide Web

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques23 A Web page is a document on the Web that you view through your Web browser The act of reading Web pages and clicking on hyperlinks is called browsing Browsing can be seen as a way of exploring Each Web page has a unique address called a Uniform Resource Locator (URL) that you can use to jump directly to it The World Wide Web

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques24 The World Wide Web World Wide Web Consortium (W3C) ( Founded in 1994 by Tim Berners-Lee Devoted to developing non-proprietary and interoperable technologies for the World Wide Web and making the Web universally accessible Standardization W3C Recommendations: technologies standardized by W3C include Extensible HyperText Markup Language (XHTML), Cascading Style Sheets (CSS) and the Extensible Markup Language (XML) Document must pass through Working Draft, Candidate Recommendation and Proposed Recommendation phases before considered for W3C Recommendation

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques25 Web browsers Popular browsers (and market share as of Jan 2005) (Source: Microsoft’s Internet Explorer: 69.9% Firefox: 18.7% Mozilla: 4.1 % Opera: 2.1% Netscape: 1.4 % Others (Safari, Camino, Epiphany, iRider, and several others...): 3.8 % Browser portability Great challenge Great diversity of client browsers in use Many different platforms also in use Difficult to Know capabilities and features of all browsers and platforms in use Find correct mix between absolute portability, complexity and usability of features

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques26 Web browsers Different browsers can be distinguished from each other by the features they support. Modern browsers and web pages tend to use many features and techniques that did not exist in the early days of the web. Some of contemporary browsers’ elements and features: ActiveX Ad filtering Autocompletion of URLs and form data Bookmarks for keeping track of frequently accessed locations Cascading Style Sheets Cookies which enable a website to track a returning user Caching of web content Digital certificates Download management DHTML Embedded images using established graphics file formats such as GIF, PNG, JPEG, SVG Flash

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques27 Web browsers Browser elements and features (cont’d) Favicons Fonts, size, color Forms for submitting information Frames and IFrames History of recently visited pages HTTPS Integration with other desktop applications Offline browsing of cached content Java applet JavaScript for dynamic content Plug-ins Session management Tabbed browsing Tables XHTML and XML

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques28 Searching the Internet Search engines Web sites that sort through by keywords and categories Google ( The rest Store information in databases Returns list of sites as hyperlinks Meta-search engines Do not maintain databases Aggregate results from multiple search engines Meta Crawler (

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques29 Fun Assignment (FA) # 1 Select a browser of your preference and: Explore all its menus and options Customize it to your needs and preferences Compare against other browsers Use it to explore Google

Fall Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques30 Links of the day FAU: Wikipedia, the free encyclopedia: Google: Contribute your own favorite links via Bb’s Discussion Board (“Useful links” forum)