Internet A global network connecting millions of computers, the Internet has more than 100 million users worldwide as of 1998, and that number is growing rapidly. More than 100 countries are linked into exchanges of data, news, and opinions. Unlike online services, which are centrally controlled, the Internet is decentralized by design. Each Internet computer, called a host (or web server), is independent. Its operators can choose which Internet services to use and which local services to make available to the global Internet community. Remarkably, this anarchy by design works exceedingly well. There are a variety of ways to access the Internet. Most online services, such as America Online, offer access to some Internet services. It is also possible to gain access through a commercial Internet Service Provider (ISP).
WWW Short for World Wide Web, the WWW (Web) is a system of Internet servers that support specially formatted documents. The most common formatting language is called HTML and supports links to other documents as well as to graphic, audio, and video files. This means you can jump from one document to another simply by clicking on hot spots. Not all Internet servers are part of the Web.
HTML Short for HyperText Markup Language, HTML is the authoring language used to create documents on the Web. It is similar to other markup languages such as SGML, although it is not a strict subset.
HTTP Short for HyperText Transfer Protocol, HTTP is the underlying protocol used by the Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page.
FTP Short for File Transfer Protocol, FTP is the protocol used on the Internet for sending files.
URL Short for Uniform Resource Locator, a URL is the global address of documents and other resources on the Web. The first part of the address indicates what protocol to use, and the second part specifies the IP address (domain name) where the resource is located. For example, the URLs below point to two different files at the domain asu.edu. The first specifies an executable file that should be fetched using FTP:
The second specifies a Web page that should be fetched using HTTP:
URI Short for Uniform Resource Identifier, URI is the generic term for all types of names and addresses that refer to objects on the Web. A URL is one kind of URI.
Web browser A browser is a software application that is used to locate and display Web pages. The two most popular browsers are Netscape Navigator and Microsoft Internet Explorer. Both of these are graphical browsers, which means that they can display graphics as well as text. In addition, most modern browsers can present multimedia information including sound and video, though they require plug-ins for some formats.
Web page A Web page is a document on the Web. Every Web page is identified by a unique URL (Uniform Resource Locator).
Home page The main page of a Web site is referred to as the site's home page. Typically, the home page serves as an index or table of contents to other documents stored at the site.
Web site A Web site is a specific location on the Web. Each Web site contains a home page (usually named index.html), which is the first document users see when they enter the site. The site might also contain additional documents and files. Each site is owned and managed by an individual, company or organization.
Web server A Web server is a computer that delivers (serves up) Web pages. Every Web server has an IP address and possibly a domain name. For example, if you enter the URL http://www.asu.edu/index.html in your browser, this sends a request to the server whose domain name is asu.edu. The server then fetches the page named index.html and sends it to your browser. Any computer can be turned into a Web server by installing server software and connecting the machine to the Internet. There are many Web server software applications including public domain software from NCSA and Apache and commercial packages from Microsoft, Netscape and others.
Client/server Client/server is a network architecture in which each computer or process on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers). Clients are PCs or workstations on which users run applications. Clients rely on servers for resources such as files, devices, and even processing power. Another type of network architecture is known as a peer-to-peer architecture because each node has equivalent responsibilities. Both client/server and peer-to-peer architectures are widely used, and each has unique advantages and disadvantages. Client-server architectures are sometimes called two-tier architectures.
Client Typically, a client is an application that runs on a personal computer or workstation and relies on a server to perform some operations. For example, an e-mail client is an application that enables you to send and receive e-mail.
Server A server is a computer or device on a network that manages network resources. For example, a file server is a computer and storage device dedicated to storing files. Any user on the network can store files on the server. A print server is a computer that manages one or more printers, and a network server is a computer that manages network traffic. A database server is a computer system that processes database queries. Servers are often dedicated, meaning that they perform no other tasks besides their server tasks. On multiprocessing operating systems, however, a single computer can execute several programs at once. A server in this case could refer to the program that is managing resources rather than the entire computer.
Server side For example, on the Web, CGI scripts are called server-side applications because they run on the Web server. In contrast, JavaScript scripts are client-side because they are executed by your browser (the client). Java applets can be either server-side or client-side depending on which computer (the server or the client) executes them.
Client side For example, on the Web, JavaScript scripts are client-side because they are executed by your browser (the client). In contrast, CGI scripts are server-side because they run on the Web server. Java applets can be either server-side or client-side depending on which computer (the server or the client) executes them.
JavaScript JavaScript is a scripting language developed by Netscape to enable Web authors to design interactive sites. Although it shares many of the features and structures of the full Java language, it was developed independently. Javascript can interact with HTML source code, enabling Web authors to spice up their sites with dynamic content. JavaScript is endorsed by a number of software companies and is an open language that anyone can use without purchasing a license. It is supported by recent browsers from Netscape and Microsoft, though Internet Explorer supports only a subset, which Microsoft calls Jscript.
Java Java is a high-level, object-oriented programming language developed by Sun Microsystems. It is similar to C++, but has been simplified to eliminate language features that cause common programming errors. Java is a general purpose programming language with a number of features that make the language well suited for use on the Web. Small Java applications are called Java applets and can be downloaded from a Web server and run on your computer by a Java-compatible Web browser such as Netscape Navigator or Microsoft Internet Explorer.
CGI Short for Common Gateway Interface, CGI is a specification for transferring information between a Web server and a CGI program. A CGI program is any program designed to accept and return data that conforms to the CGI specification. The program could be written in any programming language including C, Perl, Java, or Visual Basic. CGI programs are the most common way for Web servers to interact dynamically with users. Many HTML pages that contain forms, for example, use a CGI program to process the form's data once it's submitted. CGI is a server-side solution because the processing occurs on the Web server. One problem with CGI is that each time a CGI script is executed, a new process is started. For busy Web sites, this can slow down the server noticeably. A more efficient solution, but one that is also more difficult to implement, is to use the server's API, such as ISAPI or NSAPI. Another increasingly popular solution is to use Java servlets.
Dynamic HTML (1) Dynamic HTML refers to Web content that changes each time it is viewed. For example, the same URL could result in a different page depending on any number of parameters such as geographic location of the reader, time of day, previous pages viewed by the reader, or profile of the reader. There are many technologies for producing dynamic HTML, including CGI scripts, Server-Side Includes (SSI), cookies, Java, JavaScript, and ActiveX.
(2) When capitalized, Dynamic HTML refers to new HTML extensions that will enable a Web page to react to user input without sending requests to the Web server. Microsoft and Netscape have submitted competing Dynamic HTML proposals to W3C (the World Wide Web Consortium), which is producing the final specification.
API Short for Application Program Interface, API is a set of routines, protocols, and tools for building software applications. A good API makes it easier to develop a program by providing all the building blocks. A programmer puts the blocks together. Most operating environments, such as MS-Windows, provide an API so that programmers can write applications consistent with the operating environment. Although APIs are designed for programmers, they are ultimately good for users because they guarantee that all programs using a common API will have similar interfaces. This makes it easier for users to learn new programs.
ISAPI Short for Internet Server API, ISAPI is an API for Microsoft's IIS (Internet Information Server) Web server. ISAPI enables programmers to develop Web-based applications that run much faster than conventional CGI programs because they're more tightly integrated with the Web server. In addition to IIS, several Web servers from companies other than Microsoft support ISAPI.
NSAPI Short for Netscape Server API, NSAPI is an API for Netscape's Web servers. NSAPI enables programmers to create Web-based applications that are more sophisticated and run much faster than applications based on CGI scripts.
Cookie A cookie is a message given to a Web browser by a Web server. The browser stores the message in a text file called cookie.txt. The message is then sent back to the server each time the browser requests a page from the server. The main purpose of cookies is to identify users and possibly prepare customized Web pages for them. When you enter a Web site using cookies, you may be asked to fill out a form providing such information as your name and interests. This information is packaged into a cookie and sent to your Web browser to store for later use. The next time you go to the same Web site, your browser will send the cookie to the Web server. The server can use this information to present you with custom Web pages. So, for example, instead of seeing just a generic welcome page you might see a welcome page with your name on it. The name cookie derives from UNIX objects called magic cookies. These are tokens that are attached to a user or program and change depending on the areas entered by the user or program. Cookies are also sometimes called persistent cookies, because they are saved after a browsers is closed.
AFS Short for Andrew File System, AFS is the global file system that ASU uses to store computer files in the ASURITE system. The ASU Web servers serve files stored in AFS. There are two centrally managed web servers: ASU and PUBLIC. The ASU web server serves pages from the AFS starting from /afs/asu.edu/www. The PUBLIC server serves pages from the individual user's AFS space. Thus, the URL for access to an individual's web page would be http://www.public.asu.edu/~asuriteuserid. ASU allows all ASURITE users to serve pages from their AFS space.
ASURITE This is an acronym for the set of services offered by ASU under the umbrella of a single user I.D. and password. These services include the AFS, general purpose Unix servers, research and statistics Unix systems, and dial-in access for PPP service.