The Internet and WWW

Accessing Internet resources via a Web browser

URL (Uniform Resource Locator)

An addressing system that locates documents on the Internet.

Examples:

mb/db/human/short_list.html
ftp://bioinfo.weizmann.ac.il/pub/databases/swiss-prot/humchr20.txt
telnet://bioinfo.weizmann.ac.il
mailto:lhchalif@bioinfo.weizmann.ac.il

The "mailto" URL contains userid and host name.

Client - Server Architecture on the Web

Web Server

A repository of hypertext / hypermedia files and a software package that allows their access by Web browsers using the HTTP protocol.

             HTTP request
            -------------->
Web browser                 Web Server
  (Client)                   (Server)
            <--------------
             HTML document

HTML (Hyper Text Markup Language)

Code defining the structure, appearance and linking to other documents of a hypertext document.

Static and Dynamic Web Pages

Static HTML page

Stored as an HTML file on the Web server.

Dynamic HTML page

Created "on the fly" by a computer program at the server side.

CGI (Common Gateway Interface)

The mechanism that connects between computer programs and the Web server.