Internet, World Wide Web, Java, Intranet.
What is the Internet ? . . How computers find each other on the Internet ?
What is the World Wide Web ? . . What are URL and HTML ? . . Internet services: E-MAIL, Telnet, FTP, HTTP . . Unix User Commands
What is the difference between browsers?
Internet, WWW, Java, Intranet
What is the Internet ? -----------------------
The Internet (net) is a network of computer networks linking over 1,5 million host computers, over 40 million people, and it is growing almost exponentially. It is used by third world scientists to get the latest scientific information from American universities, by kids discussing the latest game tricks and by students finding Internet the biggest Encyclopedia ever created. Relcom (Russian Internet Service) used it as the only news line survived during the press blackout following the failed Russian coup in 1991. How computers find each other on the Internet ? ----------------------------------------------- Computers on the Internet are assembled into groups with a hierarchy described by the Domain Name System. Each machine has its own IP address, like "206.27.157.33" and Domain Name, for example "ipserve.com". Each group includes a designated router machine. Such a router keeps Domain Name Table with IP addresses and names of the machines it is capable to reach on the network. The place for the Domain Name Table on a UNIX machine is "/etc/hosts". Example: ___________________________ % cat /etc/hosts 206.27.157.33 ipserve.com ... ... ____________________________ What is the World Wide Web ? ----------------------------------- The World Wide Web (WWW) is the most popular Internet information service. WWW provides multi-media access to the Internet by incorporating graphics, pictures, sound and video into Hypertext documents. The function of the WWW is to organize any information available by Internet into documents that are easily accessed through "links". The fundamental difference between Gopher and WWW is the Hypertext structure which establishes links between diverse documents and embeds those links inside the document, alleviating the need for a hierarchical menu structure. What are URL and HTML ? ------------------------ Uniform Resource Locator The World Wide Web uses Uniform Resource Locators (URLs) to specify the location of files on other servers. A URL includes the type of resource being accessed (e.g., gopher, WAIS), the address of the server, and the location of the file. The syntax is: scheme://host.domain[:port]/path/filename where scheme is one of file a file on your local system, or a file on an anonymous FTP server http a file on a World Wide Web server gopher a file on a Gopher server WAIS a file on a WAIS server news an Usenet newsgroup telnet a connection to a Telnet-based service ftp a connection to ftp server The port number can generally be omitted. Web servers (or HTTP servers) on the Internet respond to any client request by sending requested information. The servers talk to their clients with Hyper Text Markup Language (HTML). For more details on HTML come to this place. Internet tools : HTTP, FTP, Telnet, Gopher. ----------------------------------------- HTTP stands for Hyper Text Transfer Protocol. The HTTP service is a basic WWW software on the server side, responding to client browsers requests. It quickly and consistently calls up any Web page, text, graphic, or other supported item. Most Web pages are written using the Hypertext Markup Language (HTML). This files have the .html or .htm extensions. Most Web servers automarically search for a default file named index.html or default.htm FTP stands for File Transfer Protocol. FTP software is used each time you need to upload or download a file over the Internet. Telnet is an Internet version of "dumb terminal" - character based data exchange between computers over the network. Gophers help Internet users search the network and retrieve and display the information once it is identified. A searcher may use a gopher to check a telephone directory, find census data, read frequently asked questions about numerous topics, locate government information, search library catalogs world wide. A gopher is made up of a client and a server. You will need gopher-client software and a telnet connection. Most commonly an Internet server includes at least four services: _______________________ .........[ INTERNET SERVER ] --port 25--{ E-MAIL service ] --port 23--{ Telnet service ] --port 21--{ FTP service ] --port 80--{ Web service ] ..................................... The WWW can be slow due to the large size of some Hypertext documents. The WWW clients use "browsers" for reading hypertext or Web pages. Microsoft Internet Explorer and Netscape are most popular browsers. What is the difference between browsers ? ------------------------------------------------------- There are plenty of browsers out there providing different level of HTML and Java support. Most popular are two: Netscape and Microsoft Internet Explorer. Both browsers are versatile and powerful tools for viewing HTML documents, both support the latest HTML standard. Netscape starting from version 2.0 allows small Java applications to be performed on the client side. This revolutionary change turned Web browsers into multi-platform client side enterprise applications. Built-in networking and perfect user interface made them an industry choice for creating internal network ( INTRANETs ). JVM (Java Virtual Machine) built later by Microsoft to be the best Java runner under MS Windows. Microsoft Internet Explorer integrates JVM and ActiveX capabilities together. Netscape Messenger, a component of Netscape Communicator, delivers next-generation Web based email software. Web based services became a new industry niche quickly filled with products from Hotmail.com to most complete collaborative set of Web services at Yahoo.com, Javaschool.com, and IPServe.com Netscape introduced JavaScript language for Web pages. Microsoft developed its own flavor of JavaScript providing job security to Web consultants... Now this all is a history. Although MS IE web browser takes the biggest market share, there are many other products in Unix and Windows worlds. Opera, Mozilla, Konquerer, and the list can go on and on. They all complain to HTML/XHTML standards. Teoretically we can easily change browsers. Unfortunately, small disagreements in areas like Java Script makes users to be more cautious in their choices and forces developers to test web applications on multiple browsers.
