UNIT-IV WWW

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Chapter-4 WWW Q. What is WWW?

The World Wide Web is an information retrieval system based on hypertext. In hypertext selected words or areas on the screen are expandable and leading to more details about subject. A hypertext allows you to view information without using a complex commands and without using a source of information. When a hyperlink is attached to text it is called hypertext.

The WWW enables you to access information on the internet without the use of complicated commands. This allows any user to quickly find the things most important to themselves.

Q. Explain working of WWW?

The WWW enables you to access information on the internet without the use of complicated commands. This allows any user to quickly find the things most important to themselves.

Working of WWW

Client Machine 5) Browser 4) Server

1) 2) 3)

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2) Browser interprets user’s selection and makes request from appropriate server. 3) Server accepts request and processes that request from browser.

4) Server sends requested files to browser to be interpreted. 5) Finally user receives file displayed by the browser.

Q. What is Web Browser? Explain types of Web Browsers.

A web browser is an interface that helps a computer user gain access to all the content that is on the Internet and the hard disk of the computer. It can view images, text documents, audio and video files, games, etc. More than one web browser can also be installed on a single computer. The user can navigate through files, folders and websites with the help of a browser.

When the browser is used for browsing web pages, the pages may contain certain links which can be opened in a new browser. Multiple tabs and windows of the same browser can also be opened. There are four leading web browsers: Explorer, Firefox, Netscape and Safari but there are many others browsers available.

Some web browsers is shown below.

Netscape

Netscape is one of the original Web browsers. This is what Microsoft designed Internet Explorer to compete against. Netscape and IE comprise the major portion of the browser market. Netscape was introduced in 1994.

Internet Explorer

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Safari

Safari is a web browser developed by Apple Inc. and included in Mac OS X. It was first released as a public beta in January 2003. Safari has very good support for latest technologies like XHTML, CSS2 etc.

Firefox

Firefox is a new browser derived from Mozilla. It was released in 2004 and has grown to be the second most popular browser on the Internet.

Opera

Opera is smaller and faster than most other browsers, yet it is full- featured. Fast, user-friendly, with keyboard interface, multiple windows, zoom functions, and more. Java and non Java-enabled versions available. Ideal for newcomers to the Internet, school children, handicap and as a front-end for CD-Rom and kiosks.

Google Chrome

This web browser was developed by Google. Its beta and commercial versions were released in September 2008 for Microsoft Windows. It has soon become the fourth-most widely used web browser with a market share of 1.23%. The browser versions for Mac OS X are under development. The browser options are very similar to that of Safari, the settings locations are similar to Internet Explorer 7, and the window design is based on Windows Vista.

Q. What is Web application?

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social security information, etc.) for immediate and recurrent use. And, this is done through web applications. These are all common examples of web applications.

Web applications are, therefore, computer programs allowing website visitors to submit and retrieve data to/from a database over the Internet using their preferred web browser. The data is then presented to the user within their browser as information is generated dynamically (in a specific format, e.g. in HTML using CSS) by the web application through a web server.

Another significant advantage of building and maintaining web applications is that they perform their function irrespective of the operating system and browsers running client side. Web applications are quickly deployed anywhere at no cost and without any installation requirements (almost) at the user’s end.

Web applications may either be purchased off-the-shelf or created in-house. Q. Explain about Web Terminologies.

We can run web applications then use some terms on web i.e.; web terminologies is shown below.

1.Web Page: It contains a document, written in HTML language. Which is always accessible through HTTP.

2.WebSite: It contains a collection of web pages, images, videos or other digital assets that is hosted on web server.

3.Web Browser: It contains a collection of web sites. It is a computer program that enables internet users to access and search world wide web sites. For example such as Internet Explorer, Mozilla Firefox and Google Chrome etc.

4.Web Server: It is a computer that is only used to display web sites and web pages. 5.URL: Uniform Resource Locator is the global address of documents and other resources on the world wide web.

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7.HTML: Hyper Text Mark-Up language is used to designing number of wedpages on web.

8.HTTP: Hyper Text Transfer Protocol, it is for addressing Hyper Text WebPages on the web.

9.Hypertext: It is a electronic document text that is connected to other graphical elements to which the user is transferred by a mouse click.

10.Hypermedia: It is a term derived from hypertext, that is it including multimedia objects, sounds, videos etc.

Q. Define URL? Explain the components of URL.

Definition: URL is an acronym that stands for Uniform Resource Locator and is a reference (an address) to a resource on the Internet.

A URL is actually a link, which connects you to website. This is unique address for a file that is accessible on the internet.

The following is an example of a URL:

http://java.sun.com/

The first part of the URL is called a Protocol Identifier(HTTP), it indicates what protocol to use and second part is called resource name(java.sun.com), it specifies the IP Address.

Components of URL:

This particular URL addresses the Java Web site hosted by Sun Microsystems. The URL shown above, like all other URLs, has two main components separated by a colon (:):

the protocol identifier

the resource name

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The protocol identifier indicates the name of the protocol to be used to fetch the resource. The example uses the Hyper Text Transfer Protocol (HTTP), which is typically used to serve hypertext documents. HTTP is just one of many different protocols used to access different types of resources on the net. Other protocols include File Transfer Protocol (ftp), Gopher (gopher), File (file), and News (news).

Resource name:

The resource name is the complete address to the resource. The format of the resource name depends entirely on the protocol used, but for many formats the resource name contains one or more of the following components:

host name: the name of the machine the resource lives on

filename: the pathname to the file on the machine

port number: the port number to connect to (this is typically optional)

reference: a reference to a named anchor within a resource; usually identifies a specific location within a file (this is typically optional)

For many protocols, the host name and the filename are required and the port number and reference are optional. For example, the resource name for an HTTP URL must specify a server on the network (host name) and the path to the document on that machine (filename), and can also specify a port number and a reference. In the URL shown previously, java.sun.com is the hostname and the trailing slash '/' is short-hand for the file named /index.html.

For example, When constructing any URL, put the protocol identifier first, followed by a colon (:), followed by the resource name, like this.

http://searchnetworking.website.com/

ftp://www.somecompany.com/

http://www.google.sites.com/

Q. What are Search Engines? Explain how they work.

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A program that searches for and identifies items in a database that correspond to keywords or characters specified by the user, used especially for finding particular sites on the World Wide Web.

Types of Search Engines: Crawlers-Based Search Engine:

Crawler-based search engines use automated software programs to survey and categories web pages. The programs used by the search engines to access your web pages are called ‘spiders’, ‘crawlers’, ‘robots’ or ‘bots’.

The results (list of suggested links to go to), are listed on pages by order of which is ‘closest’ (as defined by the ‘bots’), to what the user wants to find online.

Crawler-based search engines are constantly searching the Internet for new web pages and updating their database of information with these new or altered pages.

Examples of crawler-based search engines are:

 Google (www.google.com)

 Ask Jeeves (www.ask.com)

Directories Search Engine:

A ‘directory’ uses human editors who decide what category the site belongs to; they place websites within specific categories in the ‘directories’ database. The human editors comprehensively check the website and rank it, based on the information they find, using a pre-defined set of rules.

There are two major directories at the time of writing:

 Yahoo Directory (www.yahoo.com)

 Open Directory (www.dmoz.org) Hybrids Search Engine:

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 Yahoo (www.yahoo.com)

 Google (www.google.com) Meta Search Engine:

Meta search engines take the results from all the other search engines results, and combine them into one large listing. Examples of Meta search engines include:

 Metacrawler (www.metacrawler.com)

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