Скачати 34.58 Kb.
ЗмістAlgorithms of information searching in the Internet
Network addresses in the Internet
Internet Resource Locator
Address - IP address (in numerical format) or domain name of server in the Internet; Port
Search Web-sites by keywords and phrases
Searching information on Web-page
Laboratory work № 5
NAVIGATION OF WWW RESOURCES IN THE INTERNET
Practical acquaintance with built-in internet navigation system of Microsoft Internet Explorer browser and the Internet search engines.
General information about search engines
Physical and logical location of data and services in the Internet depends on the decisions of thousands system administrators. In addition, the amount of information on the Internet is increasing in geometric progression. Today there are millions of different servers in the network. So it’s impossible to rely upon memorizing of their addresses for quick access to required information. Therefore it is important to learn how to the search necessary information online and receive corresponding practical skills.
Special internet search engines (SE) helps were built to get access to a Web-site on the Internet, if its address is unknown. SE could provide a hyperlink catalogue that helps users to find Web-sites in one of a number of thematic categories. But the most useful way to use SE is the search for keywords or phrases that the user passes to SE server itself.
Different search systems have different search features and provide different menu and interfaces. Fig. 5.1 depicts a browser window, which reproduces the main page of the Google search engine (www.google.com).
The hyperlinks provide a fast navigation from one WWW place to another. The following types of hyperlinks are usually used: from specific location of initial Web page to another page (Fig. 5.2), from specific location of initial page to some other specific place on the same page or any other target Web-pages. Target and initial pages can be located on single or different computers in network. It’s possible to use text (word or phrase) or some other media objects (photo, video) for a hyperlink implementation. Hyperlinks are usually rendered on the page in different format relatively to format of the plain text.
Programs browsers typically offer two types of information search: search for information on the Internet and search for information on the downloaded Web-page. Internet search tools of browser helps to find Web-pages, Internet news group messages, etc. Local search tools of browser helps you find specific words or phrases on the active web-page. Algorithm for finding information on the Internet:
Fig. 5.1 – Start page of search system google.com
Fig. 5.2 – Types of hyperlinks in WWW
1. Click "Search" on your browser's toolbar. The result, of course, loads the page that will offer access to WWW search engines and other Internet search services.
If known address of effective search engine, in the "Address" you must enter the URL and press "Enter" on your keyboard.
2. Observe the instructions that may be filed at search system: enter text, press the search button and wait until the search engine will find this text in the database of Web-pages.
3. View search results. Certainly they are in a list of links to files that contain specified text. To improve the performance of search and navigation on the Internet you can bookmark URLs to search systems and to other information resources. You can use lists of selected pages, accessed by using the horizontal menu "Favorites" or - using the "Favorites" (Bookmarks) to your browser toolbar.
Algorithm for searching information on the active Web-page:
1. In the horizontal menu of your browser select "Edit", and in submenus – “Find on this page”. The result opens a dialog box "Find".
2. In line "Find" of the opened dialog enter text (word, phrase) you want to visit.
3. Select search area and click "Find Next" or press "Enter" on your keyboard. As a result of the search browser will highlight the text or reports that are not found.
4. To find the next desired text on this page repeat paragraph number 2 and number 3 of the algorithm.
The data in computer networks transmitted by blocks, called packets or frames. To identify sender and receiver of packet in its header indicating its computer network addresses. In the Internet, these addresses are used to route packets between computers (with using network level protocol – IP (Internet Protocol) [4, 6-8]). Therefore, the Internet addresses known as IP-addresses.
IP-address of the computer on the Internet must be unique. It provided centralized IP-addresses of computers. Main registrants of IP-addresses is: Inter NIC (Inter Network Information Center) and the organization of European providers RIPE NCC (Reseaux IP Europeans NCC).
Current version of IP protocol is fourth version (IP v.4) and implemented sixth version - IP v.6. According to the version of the IP protocol size of addresses is 32 bits (4 bytes) for IP v.4, and 128 bits (16 bytes) for IP v.6. Digital IP-address of record adopted decimal number system. For example: 18.104.22.168, where the points are separated bytes. High (left) bytes in IP-address identifies the network addresses of the highest rank in the internet, and low (right) byte - a computer on the network.
Because digital addresses is difficult for remembering in the Internet is Domain Name System (DNS), which address consists of domain names separated by points, such as: www.onat.edu.ua. In this system of domain names pointing to the computers. Information on behalf of the domain names filed in reverse order compared to IP-address. Domain name has a hierarchical structure. Highest level available in right part of domain address. This structure corresponds to the hierarchical DNS combining computer or group of domain computers in a large domain group (Fig. 5.3).
To better understand the idea of hierarchical association of computers in the domain (see Fig. 5.3) give the interpretation of the hierarchy of domains for the above domain addresses: www - the name of the computer; onat - domain name of the organization where this computer (Odessa National Academy of Telecommunications - ONAT); edu - domain name of educational organizations; ua - domain name for web-sites located in Ukraine.
By Internet standards, the highest-level domain names should be standardized. In Table. 5.1 are some standard top-level domain names and the countries or organizations which provide domain names.
Fig 5.3 – Hierarchical Domain Name System
Table 5.1 – High-level domain names in the Internet
For access to some resource user must specify the resource location, indicated by a URL (Uniform Resource Locator). URL standard and uniquely identifies the location of an information resource on the Internet. Resource locator consists of four main parts, and has the following format:
where Protocol - the name of the application layer protocol, which indicates the type of server and protocol that will be used for client-server communications at application level;
^ - IP address (in numerical format) or domain name of server in the Internet;
Port - port number - Identify the server side software on a remote server;
Path - absolute path to the file on server in terms of file system, which consists of directory names and file.
According to the Internet standards, there are dedicated port numbers for popular application protocols and services used by network operation system. For example, the HTTP protocol at web server side uses port number 80 by default. Therefore, usage of the “Port” field in the URL notation is optional and denoted by square brackets. This field is usually omitted in URLs if default port number is used and applied in case of non-standard port or explicit port selection.
For example, construct the URL, which points to the HTML-file that is placed on Web-server Odessa National Academy of Telecommunications n.a. O.S. Popov:
where http - protocol of Web services;
www.onat.edu.ua – address of Web-server;
lab/hello.html - path to the file server (lab - the name of the folder, hello - the name of HTML-file).
When you navigate Web-site http protocol name in the URL to specify the browser is optional. In this case, the browser on default will address the request to the Web-server, whose address is specified. For the above simplified example (without protocol) of URL format:
In a URL may be absent and the path to the file on the server. If the Web-browser to specify only the address of Web-server, for example, www.onat.edu.ua, then server return start page of this server.
Viewing web-site of Web-search system
1. Open the Internet Explorer.
2. Open Web-site of any search system.
For example: www.google.com, www.r0.ru.
Review information and services, which served in this website. Look where the search box to enter a keyword or phrase to search for information online. Copy search box that server to your protocols.
Viewing the site in a new browser window
7. Using hyperlinks to open in new window one of the sites found by search engines.
To do this, bring the mouse pointer on the hyperlink (in this case it may be the site address) and click on the right (by default) button. From the context menu that appears, you must select "Open in new window" and click the left button.
8. Familiar with Web-page that loads in a new window and close the window.
9. Look for searched information in the active Web-page.
To use this algorithm, which are higher in sub-section “search algorithms in the Internet”. Write down results to protocol.
Working with a list of selected pages
10. Record the URL of the current (active) page to your favorite pages of Web-browser.
In the horizontal menu bar, you should select the "Favorites", and submenus - "Add to Favorites ..." or "Add folder ..." (depending on the version of Web-browser ). In the dialog that opens, select or create a new folder, enter the label name and click "OK."
11. Open site with list of selected pages.
In the horizontal menu bar, you should select the "Favorites". In the menu that appears, select the desired label site and download it.
In recent versions of Web-browser list of selected pages can be opened on the browser toolbar. To open this panel you can use the "Favorites" on the toolbar.
12. Remove your URL recorded from selected pages of Web-browser.
In the horizontal menu bar, you should select the "Favorites", select a folder and name the shortcut and click "Remove."
Using the history
13. Open site with a history record.
In the horizontal menu bar of Internet Explorer, you should select submenus - Open history "(Open History). In the window that appears, select the desired label site and download it.
14. Close all windows Web-browser.
CONTENT OF THE PROTOCOL
|Laboratory work №4||Laboratory work №5|
|Laboratory work №4||Distributing of rating points on the types of work: 1 Work during semester|
|Distributing of rating points on the types of work: 1 Work during semester||Determination and estimation of physical work capacity in sports and clinic the terminology in physical work capacity|
|Iso 17025: Laboratory accreditation and instrument calibration||Документи|
1. /MEDICAL FACULTIES/Case report.doc
1. /MEDICAL FACULTIES/Case report.doc
1. /MEDICAL FACULTIES/Case report.doc