Lesson 1 Web Tech PDF

 Introduction to the Web Lecture Objectives By the end of this chapter the learner shall be able to; 1. Understand the concept of WWW 2. Understand evolution of internet 3. Identify the different applications of internet 4. Identify the differe...

 Introduction to the Web Lecture Objectives By the end of this chapter the learner shall be able to; 1. Understand the concept of WWW 2. Understand evolution of internet 3. Identify the different applications of internet 4. Identify the different components of the internet Meaning of WWW The acronym www stands for World Wide Web. WWW (World-Wide Web) is a multimedia service that attempts to organize all the information on the Internet as a set of hypertext documents. A hypertext document contains hyperlinks which point to other hypertext documents, as well as graphic, audio, and video files. Hypertext document are formatted in a markup language called HTML (Hyper Text Markup Language). A WWW hypertext document is usually called a web page. Operations on the WWW is based on a client/server model. Web browser (e.g. Netscape Navigator and Microsoft Internet Explorer) is a web client that access web pages resided on a web server. The World Wide Web, or web for short, is an internet based network of documents that reside on computers all over the world. The web is a universal access network, meaning anyone can access web documents from anywhere, and anyone can add pages to the giant network of pages. The web is not the same as the internet per se, but the web is the internet’s most popular service The Internet The Internet is a computer network made up of thousands of networks worldwide. All computers on the Internet communicate with one another using the Transmission Control Protocol/Internet Protocol suite, abbreviated to TCP/IP. Computers on the Internet use a client/server architecture. This means that the remote server machine provides files and services to the user's local client machine. The Internet can be considered as a world-wide network of computers, information resources, and people. The internet is a vast network of networks. The network of universities, businesses, organizations, governments and individuals from the internet. The Internet is a collection of interconnected networks. Each network is independent from its neighbours, and so ultimately, no one country or organization crowns,the Internet. There are organizations which develop technical aspects of this network, but no governing body is in control. The Internet backbone, through which Internet traffic flows, is owned by private companies. An Internet user has access to a wide variety of services: electronic mail, file transfer, vast information resources, interest group membership, interactive collaboration, multimedia displays, real-time broadcasting, shopping opportunities, and much more. Evolution of Internet The Internet had its origins in the cold war between Russia and America during the 1960's. In 1969 the Defense Advanced Research Project Agency (DARPA) of United State Department of Defense (DOD) built the first network known as ARPNET (Advanced Research Project Agency Network). The military intent was to build a network that could survive a nuclear attack. This is a network that could continue to work in the event of a war even if part of the network is broken. Four sites were connected to form ARPNET. By 1971 15 sites had been connected. By 1972 the ARPNET had increased to 37 sites. Although the U.S Department of Defense had intended to use the network for research, users also started to exchange messages with one another because it was convenient. During the early stages of development of ARPNET, there were no network standards, or universally agreed upon ways of doing things between sites. Therefore an informal process called Request for Comment (RFC) evolved to get users to agree on rules. The RFC draft would suggest possible standards or way of communicating and exchanging information, using software and protocols that everyone could probably agree upon. In 1982 the Defense Communication Agency (DCA) established one protocol known as Transmission Control Protocol and Internet Protocol (TCP/IP) as standard connection protocol used on ARPNET. In 1983 the ARPNET split into two networks i.e. MILNET and ARPNET. This was the point that marked the beginning of the true internet. Because non DOD sites were allowed to connect to the ARPNET In 1984, national networks were started in Japan i.e. JUNET (Japan Unix and Research Network) 1989 marked the first public distribution of WWW client software on the internet from CERN. The World Wide Web concept was designed and implemented by Tim Berners- Lee at CERN. Advantages of using the Internet The following are the benefits of using the internet: -  Global Audience Content published on the World Wide Web is immediately available to a global audience of users. This makes the World Wide Web a very cost-effective medium to publish information.  Relatively Inexpensive to Publish Information It is relatively inexpensive to publish information on the Internet. At a fraction of the cost to publish information by traditional methods, various organizations and individuals can now distribute information to millions of users. It costs only a few thousand dollars to establish an Internet presence and publish content on the Internet.  Product Advertising You can use the World Wide Web to advertise various products. Before purchasing a product, customers will be able to look up various product specification sheets and find out additional information. You can use the multimedia capabilities of the World Wide Web to make available not only various product specification sheets but also audio files, images, and even video clips of products in action. The beauty of the Web is that it allows customers to explore products in as much detail as they desire. If the client just wants a general overview, he or she can look at the advertising information. For those wanting more in depth information, you can provide white papers and product descriptions for download. The Web allows a business to provide timely information, you can simply place the information on the Web page and it is available immediately for your customers.  Distribute Product Catalogs The World Wide Web is a very effective medium for distributing product catalogs. In the old days, putting together a product catalog used to be very costly in terms of time and money needed to publish and distribute it. The World Wide Web changes all this by allowing content developers to put together a sales catalog and make it available to millions of users immediately. Furthermore, unlike printed product catalogs that are usually updated around once a month, product catalogs on the World Wide Web can be updated as needed to respond to various changing market conditions.  Online Surveys Traditional methods of performing surveys are often relatively slow and expensive compared to online surveys conducted on the Internet. For example, in order to fill out various needs of customers or what they would like to see in a future product, it's often necessary to compile a list of address and mail a questionnaire to many customers. The success of such an attempt is not always guaranteed and can be very costly in terms of mailing the questionnaires and entering responses to a databases and analyzing it. On the other hand, you can use the World Wide Web to automate the whole process. For example, you can set up a CGI script to conduct online surveys. Results of such a survey can be automatically updated to a database. This database can then be used to keep a pulse on various opinions and needs of customers. With the World Wide Web, you can distribute various announcements to millions of users in a timely manner. Because there is virtually no time lag from the time it takes to publish information to making the information available to users, the Web is an ideal medium to publicize announcements. As more people discover the virtues of the Web and get connected to the Internet, the Web will become the medium of choice for many organizations and individuals to publicize various announcements.  Provide Technical Support You can also use Web site to provide technical support to users. Because Web pages can be updated immediately with new information, various technical support literature can be immediately modified in light of new findings and developments. This can be accomplished without having to distribute changes to all users affected by any changes using traditional mediums of information distribution, which are often quite costly compared to the World Wide Web.  Create Online Discussion Forums By using applications such as Zoom, skype, googlemeet etc it is possible to set up online discussion forums on the Web.  Easy Integration with Internal Information Systems Internet information systems deployed on the Internet can be easily integrated with internal information systems managed with office productivity applications such as Microsoft Office.  Multimedia The capability to incorporate multimedia into Web pages is a major advantage of using World Wide Web to publish information. For example, many Web sites use sounds and video clips to make the content easier and more interesting to browse. Disadvantages of using the Internet Despite the fact that the Internet is saving our time and it is free and public, it has recently become a problem, too. Many people, especially the young, spend too much time on it. One dares to say the youth is exactly the most vulnerable group of Internet users. Scientists predict that the Internet will be one of the most problematic addictions in the future. Some people have already stopped hanging out with friends and started to live a virtual life. Furthermore, people are losing their social characteristics, they are adapting them to indirect communication on the internet. They show their emotions with symbols and signs and forgetting how to act in real society. Also, the negativities are the lack of privacy and a dangerous possibility of stealing money, information and identity, illegal distribution of music and videos, as well. Components of an Internet Major components on the Internet include:  WWW (World-Wide Web).  Email (Electronic mail)  Telnet  FTP (File Transfer Protocol  Email Discussion Group  Chat and Instant Messaging Internet Communication Services The following is a list of communication services provided by the internet: -  Email- Provide a quick convenient, efficient and cheap way to communicate with both individuals and groups. It is the most popular internet service.  Fax services- Offers individuals and business the option of sending fax via email at substantial savings over conventional international fax charges.  Internet fax subscribers can send faxes from their computers to another fax machine or to multiple destinations.  Chat- Allow a large number of people to exchange information among themselves in real time, from various locations. To chat you need to get connected. Once connected you need to join a channel. You normally will be able to know all the channels currently operating and the number of people logged onto them  Conferencing- It the dynamic exchange of all kind of information, text, graphics, HTML links, audio and video e.t.c. in a context of structured conversations organized by items. It allows participants to contribute responses to any item in the conversation. The objective of such a structure of online conversation may be decision making, technical support, project management, distant education e.t.c Opportunities provided by using Internet The following are the services provided by the internet: - i. Commerce and Industry The greatest impact on world economy is due to what the internet offers to facilitate trade. Internet has provided the following opportunities under commerce and trade:-  Business communication-Providing product information, placing and tracking orders, handling enquires, providing follow up services an obtaining customer feedback.  Advertisement- Gives access to a large pool of customers. This completely removes the need for middlemen.  Ability to buy from a large pool of producers –Those wishing to buy products through the internet have access to world wide information.  Trading information- Allows one to keep up to-date with trading information on stock exchange. One can conduct research on company information, check stock quotes or link resources that will provide insight to the market place.   Tourism industry- Tourist sectors are now using internet to advertise themselves. For instant by hosting websites that give details on facilities offered. ii. Manufacturing- Internet allows us to select the best, most appropriate raw materials for products from a wide list. The network is also used to ensure that customers and suppliers share real time data about demand, shipment, order status an inventory. iii. Education The education system has benefited tremendously from the adoption of the Internet in education. Students and educators now have instant access to a virtually endless library of information. The Internet has made it possible for educators to share the latest updates in their subject to students and share multimedia with them. iv. Research Internet helps researchers carry out review of journals. Internet has increased cooperation efforts in selected joint research projects of common interests. v. Health Internet provides daily news about health care and health resources. It makes it possible for hospitals in one country to use consultants from another country. This reduces traveling costs. It also provides access to latest development on medical research and drugs. vi. News and information Helps us get headlines and in depth stories. This is through CNN, News link, major online papers and magazines. vii. Online shopping Allows one to browse online for items such as electronics, groceries e.t.c viii. Online Banking Internet enables one to check bank balances, statement at the comfort of his/her home. ix. Provide job opportunities Helps one land a job if one is a potential employee or locate the perfect employees if one was an employer. The internet also avails job tips and information on job interviews x. Software downloading Provides access to a large pool of soft wares, most of which are public domain (free). This is extremely helpful especially when new softwares have been released or existing ones require upgrading. Internet security Internet security and firewalls deals with issues of protecting ones internal network from the internet. Today anyone with a computer and a modem can have access to the internet. Not everyone accessing the internet have good intentions. Secondly, not all web sites on the internet have been built with good intention. There are a great number of people accessing the internet with ulterior motives. Some want to steal information, others want to destroy certain or any information they come across. There are also a great deal of hostile web sites on the internet whose objectives are to harm those visiting them. Internet security deals with identifying a security policy for company network. A policy would consist of which users on the internet or internal network should have or not have access. if security policies are not in place a company’s site not only will employee have access to internal information from the internet, but also anyone else who is connected to the internet. Internet Security Threats Technology has become an inevitable part of our lives and while Internet offers a mass amount of useful information, makes communication easier and faster than ever, it presents some threats too along the way. These threats include:- Virus Virus is a program designed to copy itself and propagate, usually attaching itself to applications. It can be spread by downloading files, exchanging CD/DVDs and USB sticks, copying files from servers, or by opening infected email attachments. Trojan Trojan might appear harmless and even useful at first, but it leaves your PC unprotected, enabling hackers to steal sensitive information. Spyware Spyware is often secretly installed without users consent when a file is downloaded or a commercial pop-up is clicked. Spyware can reset your auto signature, monitor your keystrokes, scan, read and delete your files, access your applications and even reformat your hard drive. It constantly streams information back to the person that controls spyware. Adware This malware launches advertisements, mostly in the form of pop-ups. These are customized to you as a user, based on your behavior on the Internet, which may be monitored by spyware. Spam Spam may be defined as unwanted emails. Most users are exposed to spam, which is more than 50% of all Internet emails. Though spam is not a direct threat, it can be used to send different kinds of malware. Phishing Phishing is the fraudulent acquiring of sensitive personal information such as passwords and credit card details. This is accomplished by sending official-looking emails impersonating a trustworthy sender. Users of online banking and auction sites are most likely to become a target. Pharming Pharming is a more sophisticated form of phishing. By exploiting the Domain Name System (DNS), pharmers can create a fake website that looks like a real one for instance web bank page, and then collect the information users think they are giving to their real bank. Keyloggers Designed to record the user’s keystrokes. Keylogging allows criminals to look for particular bits of information that can be used for identity or intellectual property theft. Rogue security software A special type of threat is software that claims to be security software. It tricks users that have installed it to pay a sum of money to be really protected (which they will not be). Most often it pretends to be antivirus and antispyware programs. Browsing the web Using software applications known as the browsers you can find just about any information you can imagine on the web, or buy any product or services that is available. With a browser you can access a web site, which is a collection of documents, or pages that typically contain text and images. Pages on the web are connected with hyperlinks. With a single click, you can jump from one page that is stored on a server in Kenya to another page that is stored on a server in another country across the globe. Important components of the web Web Server A Web server is a computer that is set up with software and networking capabilities to deliver Web pages on the Internet or an Intranet. Web servers use programs such as Apache or IIS to deliver Web pages over the http protocol. The primary function of a web server is to deliver web pages to clients. This means delivery of HTML documents and any additional content that may be included by a document, such as images, style sheets and JavaScript’s. Using the HTTP protocol, the Web server delivers Web pages to browsers as well as other data files to Web-based applications. The Web server includes the hardware, operating system, Web server software, TCP/IP protocols and site content (Web pages, images and other files). If the Web server is used internally and is not exposed to the public, it is an “intranet server†Universal Resource Locator (URL) Universal resource Locator (URL) is a web address. For example the URL for KCAU home page is http://www.kcau.ac.ke Structure of URL Address It consists of three parts   A protocol part for accessing documents on the web e.g. http://  A host part or the domain name e.g. www.kcau.ac.ke  A document name file name of a specific document in a web site e.g. www.kcau.ac.ke/student portal A URL can be typed into the Address bar Window of a web browser. What are the parts of a Web Address (URL)? Universal Resource Locator (URL) is the exact address for a particular Web page. The parts of the URL can give you clues about where a page is located and what type of company or person owns it. See the figure below. A URL has three main parts: WWW Host Name or Web Server GOOGLE Domain name (Usually the owners name) COM Top level domain. It is the last section of the URL. Informs you of what type of organization own the address The most common single-section endings are:.com commercial site but also used by individuals.org usually non-profit organizations.edu educational site.co.uk commercial site located in the United Kingdom.gov government site Types of URLs File URLs These are used to access files on the network. For example if there is a document called foobar.txt on an ftp server called ftp.yoyodyne.com in a directory called /pubs/files the URL for this file will be: File://ftp.yoydyne.com/pub/files/foobar.txt The top level directory of the FTP server is simply; File://ftp.yoydyne.com/ Gopher URLs Gopher URLs are used to access Gopher sites. Gopher servers are more complicated than FTP servers. In addition to the name of the server you need to know the network port on the host machine.The default gopher port is 70. If you have to use a port that is different, then you need to specify it.For example, if the gopher server on the machine gopher.banzai.edu is on port 1234 instead of port 70, then the corresponding URL will be: gopher://gopher.banzai.edu.1234/ If the default port is used, then you do not need to specify the port number. To visit a gopher server on gopher.yoyodyne.com on port 70, use the URL: gopher://gopher.yoyodyne.com/ HTTP URLs HyperText Transfer Protocol (HTTP) servers are commonly used for serving hypertext documents. To access a file called foobar.txt on HTTP server, www.yoyodyne.com in directory /pubs/files on the URL will be: http://www.yoyodyne.com/pub/files/foobar.html The default HTTP network port is 80; if a HTTP server resides on a different network port for example port 1234 on www.yoyodyne.com then the URL will be; http://www.yoyodyne.com:1234/pub/files/foobar.html Links allow you to move from one Web page or section to the next by clicking on text or objects. On many pages the text will be underlined and/ or sometimes in a different color. Also, if your pointer turns into a hand, this indicates a link for you to click. Clicking on a link will take you to another Web page with more information. Home Page A home page is typically the first page of any Web site. You can set your own home page in your Web browser. The library has selected Web site as the home page for all browsers. It will be the first page to be displayed when the browser opens. Web browser A web browser is special software designed to display Web pages and links. A few examples of popular browsers today are Microsoft Internet Explorer, Mozilla Firefox, Netscape and Opera. Web browsers are free software programs that allow you to surf the web, once you have the appropriate connection in place. Popular web browsers include: Internet Explorer (built-in to Microsoft operating systems), Safari (included with Macintosh operating systems) and Firefox (a free, customizable browser). Google has also released a new web browser, Google Chrome. AOL comes with its own web browser (AOL), built on Internet Explorer. Cache - Browsers cache (or save) online web pages and pictures in a temporary folder on your computer to speed up your Internet time (when you revisit the site, it pulls the images and text from the cache instead of the server). This is great for speed, but it takes up space on your computer. Cookies - A cookie is a bit of information about you that another computer stores on your computer (it may keep track of passwords or user preferences). Amazon.com uses this to track your book interests; The New York Times online uses this to save your password. History - Your web browser keeps track of all pages you visit in a day. Activities Activity 1 Browse the web http://www.google.com  Lycos - http://www.lycos.com Web Crawler - http://www.webcrawler.com Yahoo - http://www.yahoo.com The Essentials of Google Search 1. Run any web browser installed in your computer 2. On the address bar of your Internet explorer, type this address: http://www.google.com 3. The Google webpage will be displayed 4. Doing a search on Google is easy. Simply type one or more search terms (the words or phrase that best describe the information you want to find) into the search box and hit the 'Enter' key or click on the Google Search button. In response, Google produces a results page: a list of web pages related to your search terms, with the most relevant page appearing first, then the next, and so on. Further Reading 1. Find out the applications of the internet 2. Research more on social networks and their effects to the modern society References Albert, R., Jeong, H., & Barabási, A. L. (1999). Internet: Diameter of the world- wide web. Nature, 401(6749), 130-131. Lawrence, S., & Giles, C. L. (1998). Searching the world wide web. Science, 280(5360), 98-100. Fetterman, D. M. (1998). Webs of meaning: Computer and Internet resources for educational research and instruction. Educational researcher, 22-30.  Explanation of the internet for better understandingPage