Today the WWW (World Wide Web) is the hottest example of distributed information and electronic publishing. It can be simultaneously global and local, complex and easily extensible, and corporate and personal. The basic tools and organization allow anything from a simple one-site setup to a link to the worldwide community.
The WWW is based on the concept of
hypertext
-- documents with links to other documents, which lets you follow related ideas from one place to another. In some sense, it's an extension of linked help files. Instead of being bound to one file, documents can be spread across files, and even across computers. For example, if you're writing a document and want to create a link to something on a computer at some other site (even at another company, university, and so on), you j
ust tag your hot spot with the name of the remote computer and the file. The figure
"Linked Documents"
shows how some hypertext-linked documents can be connected.
Even more powerful is the concept of the
form
, which is, in essence, a dialog box with check boxes, radio buttons, pull-down menus, and fields for editing. As an author, you design a form with the desired buttons, menus, and so on. You also write a program (in virtually any programming language), called a CGI (Common Gateway Interface) application, to handle the input--filling an order, adding a reader's name to a mailing list, looking up information, whatever you want.
At this point, you've created an interactive publication. A subscriber reads your pages and fills out your form. Your program then does something with the form's data, and you create a new page for the subscriber based on that data.
But how does it work? A fully functional WWW relies on three components to function together seamle
ssly: your computer (and its software), a set of network links, and one or more other computers acting as servers (see the figure
"Components of a WWW Site"
).
A WWW setup functions similarly. On your computer, you use what's known as a
browser
to view published pages, regardless of where the pages are physically located. Each hot spot in a document knows the name of its associated file and on which computer (i.e., server) that file is stored. When you select the hot spot, the browser goes across the network to the server, asking the server for the file. The server responds with the file, and the browser proceeds to display the information.
The name of the computer and the file are combined into something called a
URL
(uniform resource locator). A typical URL might be something like http://s1/byte.html, which says to retrieve the file byte.html from the server s1 using a method called Hypertext Transport Protocol, or HTTP. URLs support several other t
ransport protocols, including Gopher and FTP.
The four main tasks involved in completing the WWW publishing cycle are setting up a network, the server, and the browsers on the users' workstations, and, finally, creating the pages and forms-processing programs.
INTERNET GLOSSARY
Archie
A software tool for finding files stored on anonymous FTP servers. FTP sites are regularly indexed by title and keyword, and Archie searches these indexes for files based on your search criteria.
Firewall
A security barrier, consisting of one or more routers capable of accepting, rejecting, or editing transmitted information, placed between an organization's internal network and a connection to the Internet.
FTP (file transfer protocol)
A protocol used to transfer files between Internet sites located across TCP/IP networks.
Gopher
A hierarchical text database that makes menus of material available over the Internet.
Gopher is a client/server application that lets surfers drill down through a hierarchy of descriptions, narrowing the search until you find the document you need.
HTML (Hypertext Markup Language)
A coding language used to create hypertext documents for use on the WWW.
HTTP (Hypertext Transport Protocol)
A protocol for moving hypertext files across the Internet. Requires an HTTP client program on one end and an HTTP server program on the other. HTTP is the most important protocol used by the WWW.
S-HTTP (Secure Hypertext Transport Protocol)
A transaction protocol for the Internet that creates secure channels at the application layer.
SLIP (Serial Line Internet Protocol)
A standard for using a regular telephone line (a serial line) and a modem to connect a computer as an Internet site. SLIP is gradually being replaced by another standard protocol, called PPP (Point-to-Point Protocol), that encapsulates transport protocols in spe
cial packets.
URL (uniform resource locator)
A uniform method of specifying where different documents, network resources, and media reside on the Internet.
WAIS (Wide Area Information Service)
A document-database server that allows the indexing of huge quantities of information and then making those indexes searchable across networks, such as the Internet.
WWW (World Wide Web)
A network of servers that use HTTP to link documents across the Internet. The WWW connects Gopher, FTP, and WAIS servers, making them transparent to the end user.
illustration_link (8 Kbytes)
Hypertext links let you navigate across documents (and WWW sites) by clicking on highlighted terms.
illustration_link (31 Kbytes)
A fully functional WWW site requires a computer (with software), a set of network links, and servers.
How the WWW Is Put Together
