Laboratory work № 4
LEARN Internet Explorer WebBrowser
ANNOTATION
Practical acquaintance with graphical user interface (GUI) and possibilities of the Microsoft Internet Explorer (IE) software. Browsing of a Web Sites in the Internet.
LEARNING MATERIALS
Global characteristics of the Internet
The Internet is a global system of interconnected computer networks that interchange data by packet switching using the standardized Internet Protocol Suite (TCP/IP – Transmission Control Protocol / Internet Protocol). The Internet is a "network of networks". It consists of millions of private ,public, academic, business and government networks of local to global scope that are linked by copper wires, fiber-optic cables, wireless connections, and other technologies.
The Internet was developed on base of the ARPANET network, thathas been deployed by Advanced Research Projects Agency (known as ARPA) on 1969. In 1983 the TCP/IP (stack of protocols) becomes in-use on majority of the key computersof the ARPANET, boosting development of the Internet.
In computing, a protocol is a convention standard that controls or enables the connection, communication, and data transfer between interacting endpoints. In its simplest form, a protocol can be defined as the rules governing the syntax, semantics, and synchronization of communication. Protocols may be implemented by hardware, software, or a combination of the two.
There are four layers in the TCP/IP stack architecture: link layer, internet layer, transport layer andapplication layer. The layers near the top are logically closer to the user application, while those near the bottom are logically closer to the physical transmission of the data.Internet protocols defined in the set of documents called RFC (Requests for Comments). RFC documents are enumerated.For example, RFC 793 describes the TCP protocol (the transport layer).
The Link Layer is the networking scope of the local network connection to which a host is attached. This is the lowest component layer of the Internet protocols, as TCP/IP is designed to be hardware independent.
As originally defined, the Internet layer (or Network Layer) solves the problem of getting packets from the source network to the destination network. This generally involves routing the packet across a network of networks, known as an internetwork or internet (lower case).
The Transport Layer's responsibilities include end-to-end message (between interacting processes) transfer capabilities independent of the underlying network, along with error control, fragmentation and flow control.
The Application Layer refers to the higher-level protocols used by most applications for network communication. Examples of application layer protocols include theFile Transfer Protocol(FTP) and theSimple Mail Transfer Protocol(SMTP). Data coded according to application layer protocols are thenencapsulatedinto one or (occasionally) more transport layer protocols (such as the TCP or UDP (User Datagram Protocol)), which in turn use lower layer protocols to effect actual data transfer. There are traditional services in the Internet: file transfer, e-mail, remote terminal emulation. At present time the Internet infrastructure provides many other application services in addition to traditional ones,the most popular of them are: WWW, interactive conferences, news groups, video on demand, electronic payments, IP-telephony, etc.
World Wide Web service of the Internet
World-Wide Web (also commonly abbreviated as "the Web", WWW or W3) is the world's most powerful networked information system. It was originally conceived and developed at CERN (European Center Nuclear Research), where large high-energy physics collaborations created a demand for instantaneous information sharing between physicists working in different universities and institutes all over the world. Using concepts from earlier hypertext systems, the WWW was begun in 1992 by the English physicistTim Berners-Lee, now the Director of theWorld Wide Web Consortium, andRobert Cailliau, a Belgian computer scientist, while both working atCERNinGeneva,Switzerland. In 1990, they proposed building a "web of nodes" storing "hypertext pages" viewed by "browsers" on a networkand released that web in 1992.Now WWW has millions of academic and commercial users.
The terms Internet and World Wide Web are often used in every-day speech without much distinction. However, the Internet and the World Wide Web are not one and the same. The Internet is a global data communications system. It is a hardware and software infrastructure that provides connectivity between computers. In contrast, the Web is one of the services communicated via the Internet. It is a collection of interconnected documents, graphics, multimedia objects and other resources, linked by hyperlinks.
The WWW are based on a set of protocols and agreements that have been implemented in proper software and allowing access to information over the Internet. The main concept of WWW is network distribution of information resources. This approach uses not hierarchy web links between documents via a universal resource locator URL (Uniform Resource Locator), which completely specifies where an identified resource is available on the Internet and the mechanism for retrieving it.
The hypertext WWW servicesallow any user to add new information, search and view it easily. That’s why the Internet gained popularity in various fields of human activity (education, science, business, politics, etc.).
The WWW service is based on using of the Webservers. The termweb servercan mean one of two things:
- Acomputer programthat is responsible for acceptingHTTPrequests fromweb clients(user agentssuch asweb browsers), andservingthem HTTP responses along with optional data contents, which usually are web pages such asHTMLdocuments and linked objects (images, etc.).
- Acomputerthat runs a computer program as described above.
The termweb clientcan mean one of two things:
- Acomputer programthat is responsible for generating HTTPrequests, sending it to web servers and handling responses.
- Acomputerthat runs a computer program as described above.
The most commonly used (but not the only one) type ofWeb client is the Web browser. A Web browser is a software application which enables a user to display and interact with text, images, videos, music, games and other information typically located on a Web page at a Web site on theWorld Wide Webor alocal area network. Text and images on a Web page can containhyperlinksto other Web pages at the same or different Web site. Web browsers allow a user to quickly and easily access information provided on many Web pages at many Web sites by traversing these links. Web browsers formatHTMLinformation for display, so the appearance of a Web page may differ between browsers.
Viewing aWeb pageon the World Wide Web normally begins either by typing theURLof the page into aWeb browser, or by following ahyperlinkto that page or resource. The browser then requests the resource by sending anHTTPrequest to the Web server at that particular address. In the case of a typical Web page, theHTMLtext of the page is requested first andparsedimmediately by the Web browser, which will then make additional requests for images and any other files that form a part of the page. Having received the required files from the Web server, the browser thenrendersthe page onto the screen as specified by its HTML, or other Web languages. Any images and other resources are incorporated to produce the on-screen Web page that the user sees.Most Web pages will themselves containhyperlinksto other related pages and perhaps to downloads, source documents, definitions and other Web resources
The additional functionality of Webbrowser includes creating user-friendly interface, providing necessary means of navigation in Weband appropriate level of security to protect computer resources from malware and hacker attacks.
The HTMLfile is special text file that contains text and formatting directives (called “tags”) of Hyper Text Markup Language (HTML). To distinguish tags from text information the tag bracketing syntax is used in HTML language.For example: <CENTER>, </ CENTER>.
Browsers receiving HTML-file under commandsof HTML language make formatting of interpret text reflect Hypertext information graphics sound video. E.g. text HTML-file which will uploaded between specific above commands browser show at center line of region viewing. In Annex 1 reproduced HTML-file simple Web-page that reflected in viewing area browser windows fig. 4.1.
Hypertext (Hypertext) - this document is organized using the relations between the key elements that allow access to your information in any sequence. This information can be placed in one or in various documents that may be on the same or different computers on the network.
Data exchange between Web-browser and Web-server is using hypertext transfer protocol HTTP (Hyper Text Transfer Protocol). This application-level protocol of TCP/IP family, which provides WWW service on the Internet.
Addition of HTTP browsers may support other application protocols. This, for example, the following protocols: FTP, Telnet, Gopher, WAIS, Mailto, News and others. They should be used, depending on which object the user will ask for the Internet. For example, to copy files from FTP-servers to the Internet user can use the protocol FTP. To send e-mail can use SMTP.
Versions of Web-browsers
Now there are a many count of server and client software for WWW, many of which are distributed free. Among its are browsers that work with ASCII strings or browsers that support graphical user interface. Today the most famous and popular visual media browsers: Microsoft Internet Explorer and Mozilla Firefox. Browser Internet Explorer is part of the network operating systems (OS) Windows. Currently developed and uses the next browser versions of Microsoft Internet Explorer: old versions of Internet Explorer: from v.2 to v.5, new browser versions: from Internet Explorer 6 to IE 8 (with multi-tabs window, etc.).
There are versions of the above browsers, Microsoft Internet Explorer with russian and ukrainian interface.
Characteristics of Internet Explorer 6
Version of the browser Microsoft Internet Explorer 6 has a functionality of previous versions and, in addition, has some peculiarities. Here are the basic functional features of the browser Microsoft Internet Explorer 6:
1.Improved performance of Web-site review by caching mode while downloading sites in new windows and possible disabling multimedia content loading.
2. Support audio and video formats.
3. Support several different character encodings of Web-pages.
4. High level of security and privacy through the use of authentication technologies, digital signature technology and PCT (Private Communication Technology).
5. In-build mail client MS Internet Mailand Internet News client.
6. Support for object-oriented programming language Java.
7. Support for Scripting Languages VB Script (Visual Basic Script) and Java Script.
8. Support for frames - the opportunity to share the view on independent dynamic and static parts.
9. Using technology ActiveX, which enhances the browser. For example, the browser Internet Explorer you can open files, Microsoft Office, image formats GIF, JPEG and play video and sound recording format.
Graphic interface of the Internet Explorer 6
The controls of the Internet Explorer 6 conform to the window interface standards of MS Windows. Browser window consists of the following elements: Title bar, Menu, Toolbar, Address bar, View-section, Status bar (see Fig. 4.1). You can delete or modify some of these windows using the "View" menu commands.
Figure 4.1 - The window of Internet Explorer.
All ofactions in a browser may be induced by using menu commands or buttons on the toolbar. The English version of the Internet Explorer main Menu has the following command:
"File" - to work with files (open, save, print, etc);
“Edit” - for the text processing (select, delete, copy, etc);
"View" - for removal or changes to the browser window (menu, toolbar, font), and view HTML-sourceof loaded file;
"Favorites" - to work with the favorite pages (add, delete, open);
“Service” - configuration settings of the browser program (connections, multimedia, security, etc);
"Help" - to obtain information about the program and the textbook on Web.
Toolbar Browser has buttons through which the navigation information on the Internet:
"Back" - to go to the previous Web-page;
"Forward" - to go to the next Web-page;
"Stop" - to stop loading the current Web-page;
“Refresh” - to refresh the current Web-page;
"Home" - to download the home Web-page;
"Search" - to search on the Internet search engine;
"Favorites" - to see a list of favorite Web-pages on the browser toolbar;
"History" - to see hitstory-log on the browser toolbar;
"Mail" - to send or receive mail throw Internet mail server;
"Print" - for printing on the printer the current Web-page.
Every Web-page is in its Internet address. To access Web-page in a box "Address" the address bar of your browser to enter from the keyboard of its address (URL) and to press "Enter".
TEST QUESTIONS
1. What is the Internet?
2. Whatpopular Internet services do you known?
3. What service isprovidedby the Web?
4. What is Web-server?
5. What is Web-browser?
6. What is defined by the URL?
7. What is the HTML-file?
8. What is the HTTP?
9. What is hypertext?
10. What are the principles of logical links between hypertext documents?
11. Whatpopular multimedia Web-browsers do you know?
12. What file types can be openedby Microsoft Internet Explorer?
13. Identify the elements of the Microsoft Internet Explorer window.
14. What isthe purpose of the "View" menu of your browser?
15.What is the purpose of the "Stop" buttonat your browser's toolbar?
16. What is the purpose of the "Refresh" buttonat your browser's toolbar?
HOME WORK
- Study the learning materials.
- Prepare written answers to the test questions.
- Look through the laboratory tasks.
LABORATORY TASKS
Introduction to Webbrowser window elements
1. Run the Internet Explorer (IE). The IE shortcut can be found on the desktop of your computer. Alsoyou can use MS Windows "Start" menu.
2. Find the positions of following elements of the Webbrowser window: Title bar, Menu, Toolbar, Address bar, View section, Status bar.
3. Remove and restore elements of the browser window: toolbar, address bar, status bar. In the menu you should select the "View" and vertical submenus - the necessary commands.
4. Familiar with the Context menu of your browser. Mark commands in the protocol. The Context menu available after pointing the mouse pointer on the view or address bar and pressing the right mouse button.
View Web-site on the Internet
5. Open Web-site on the Internet by entering a path (URL) to Web-pages on the Web-server: To do this in the "Address" (Address) toolbar using keyboard to type the above URL and press "Enter". Another technology is opening the site. Select the "File" ( "File") in the menu, and vertical sub-menu - click "Open" (Open). In the dialog that opens, enter the URL and click OK. As a result, the browser downloads and shows Web-page (see Fig. 4.1).
View Source HTML-File
6.Open source-code of HTML-file the above Web-page.
In the menu, you should select the "View" and vertical sub-menu "View HTML-code" or "Source" (Source).
7.Another way for open source-code of HTML-file - using the context menu. To bring the mouse pointer on the view, click the right mouse button and choose from the menu command "View HTML-code”.
8. Compare the text of the original HTML-file with text that is displayed in the viewing window of Web-browser. Make conclusions.
Note commands (tags) of HTML on the HTML-file. With this tags Web-browser displays text, images and html links. Listing from the original HTML-text file hello.html presented in Appendix 1.
9. Close the original HTML-file.
Copy the Web-Pages
10. Copy active open Web-page in the "Labor" folder.
In the horizontal menu, you should select the "File", and submenus - "Save as ...". In the dialog box that appears, select or create a new folder, enter the name of HTML-file and click "Save."
11. Copy a text file of the text displayed in the viewing window of Web-browser. To do this using the left mouse button for select the object (text, picture), but with the right button - choose from the context menu “Copy” command. Open any created by you text file. Copied to the clipboard item to paste the text of the file. Close Web-browser and a text file.
View saved Web-Pages
12. Open the "Labor" folder with saved HTML-file.
13. Fix in the protocol Web-browser window and the text displayed in the view section.
Editing saved HTML-file
14. Open source-code of stored HTML-page file.
15. Change the font size of text lines displayed by your browser.
This find command language HTML, which sets the browser font size line of text, for example, <FONT SIZE=+0> and change this size, like this <FONT SIZE=10>. Indicate the changes in the protocol.
16. Close HTML-code file, saving the changes.