AIX Tip of the Week: Internet Terminology

Audience: IT Managers, Administrators and Users

Date: March 10, 2000

Don't know Beans about Java? Can't tell an Applet from a Servlet? About to loose your Cookies? Dont' despair. The following tip lists some of the more common Internet terminology.

The above picture shows a hypothetical network, with common Internet terminology listed below the component where it is displayed or run. In some cases where a term runs between components (e.g. mail), the term was placed under the network. The definition of each term is listed below. The list is not meant to be comprehensive, but rather to provide AIX users and administrators a familiarity with some of the more common Internet terminology.

ActiveX® - ActiveX was developed by Microsoft to provide functions similar to Java. These functions are not directly available in HTML, and include animation sequences, forms processing, spreadsheet calculations, etc. ActiveX differs from Java in that it runs predominately on Microsoft.

Applet - A small-program that can be downloaded and run by any computer equipped with a Java or ActiveX capable browser.

Application Server - A backend server that runs applications based on HTTP requests from a web server. The Web and Application server often reside in the same physical box.

ASP® (Active Server Page) A method for creating programs that run on a Web server. Developed by Microsoft as a Windows based alternative to JavaServlets. See also CGI programs.

Backend A generic term for processes that provide data or applications for the web server. Backend processes may be located on the Web server, or reside on dedicated servers.

Browser A client program used to view, download, upload, or otherwise access documents pages on the World Wide Web.

C/C++- Programming languages commonly used for CGI programming.

CGI - (Common Gateway Interface) A standard method of enhancing Web server functionality by executing programs on the Web server in response to browser requests. A common use of CGI is in form processing, where a user fills in a form on their browser, and sends it to a CGI script on the Web server. The CGI script extracts the data, processes it, and sends the results back as an HTML page. CGI can be Unix shell scripts, PERL scripts, or C/C++ programs.

Cookie - A small text file stored on a client’s hard drive by a web site. Cookies contain information about the client. The cookie is updated with each return visit to the web site, which allows the Web server to personalize the web page, create shopping carts, display local time and weather, etc. In theory, cookies do not contain sensitive information, and can be read only by the web site that created it.

DataBase Server Server that stores data, such as orders, inventory, shipping status, customer information, etc. Databases are typically based on SQL and are accessed using protocols such as ODBC, JDBC or sockets.

DHCP (Dynamic Host Configuration Protocol A way to allocate TCP/IP addresses on demand. A DHCP server assigns an IP address to client computers at boot time, and retrieves the IP addresses when they disconnect. DHCP has several benefits: it reduces the number of IP addresses (which are in short supply), reduces support because mobile workers do not have to reconfigure their PC when they move between offices, and it makes it easier to reconfigure the network because clients are automatically configured.

DHTML- (Dynamic HyperText Markup Language) – An up and coming version of HTML that is still being designed. DHTML resolves problems associated with laying out WebPages.

DMZ (DeMilitarized Zone) Many companies have a series of firewalls that become progressively more secure as you move from the external Internet to the internal Intranet The DMZ is the semi-secure region between the inner and outer firewalls..

DNS - (Domain Name Server) A DNS server translates host names (e.g. ibm.com) into IP addresses. IP addresses are underlying method for making web connections.

E-Mail- (Electronic Mail) An electronic means of sending a message from one computer to another. Email transmission over the network uses the SMTP protocol (between mail servers). Users access email on the server using either a POP or IMAP protocol.

Firewall - A logical barrier between an internal network and an external network, such as the Internet. A firewall consists of one or more hardware and software systems. It controls the access and flow of information between trusted systems and untrusted systems. Firewalls come in several varieties, including Application Gateway (Proxy), Transparent Gateway (Socks), Packet Filtering (screening routers), Network Address Translation, and IP Tunnels (VPN).

FTP- (File Transfer Protocol) – The basic program for copying files over a TCP/IP network.

HTML- (HyperText Markup Language) - The document formatting language used by web pages. HTML uses tags like <h1> and </h1> to structure text into headings, paragraphs, lists, tables, hyperlinks and more.

HTTP- (HyperText Transfer Protocol) - The basic method for exchanging information between HTTP servers and clients on the web. The HTTP specification lays out the rules of how Web servers and browsers work together.

IMAP - (Internet Mail Application Protocol) E-mail protocol for clients. The most significant difference between POP and IMAP, is that IMAP clients leave the mail on the server, rather than downloading and removing it from the server as POP clients do.

IRC - (Internet Relay Chat) An Internet program that allows two or more network users to participate in a live conversation by typing messages to one another. An example of IRC is AOL "chat room."

IP - (Internet Protocol) - This protocol is used in conjunction with TCP to form a method to communicate over a network.

Java® - A general purpose programming language developed by Sun Microsystems. Java programs can be compiled once and run on any platform. Depending on where they run, Java programs can be servlets (run on the server) or applets (run on clients).

JavaApplet - A Java program that is attached to a HTML Web page and executed on a client computer (running the Web browser.) JavaApplets provide features not found in HTML, such as animation sequences, form field checking, local computation. JavaApplets provide similar functionality to ActiveX.

JavaBeans® - A portable, platform-independent reusable component model. Beans can be combined to create an application. JavaBeans allows developers to create reusable software components that can then be assembled together using visual application builder tools such as IBM's Visual Age for Java.

JavaServlet - A Java program that runs on the Web/Application server. JavaServlets provide a variety of functions including the creation of dynamic web page content, process forms from browsers, do calculations, and access databases.

JavaScript®- A scripting language from Netscape that is used in both browsers and Web servers. Although functionally similar, it is not Java. Java is a compiled program, while JavaScript is a list of text commands inserted in an HTML page.

JDBC - (Java Data Base Connection) An industry standard for database-independent connectivity between the Java platforms and a wide range of databases. The JDBC interface provides a call-level API for SQL-based database access.

MIME - (Multipurpose Internet Mail Extensions) – An email protocol that enables the transmission of "Attachments," or non-text data such as graphics, audio, video and other binary types of files in an e-mail message.

ODBC - (Open DataBase Connectivity) An API developed by Microsoft to provide connectivity between applications and databases.

PERL - (Practical Extraction and Report Language) One of the most popular CGI programming languages that run on a Web server. Used to create dynamic web pages, process forms, store/retrieve data. PERL is associated mainly with UNIX based Web servers.

POP - (Post Office Protocol) – An email protocol that downloads messages from a mail server to the client for viewing. Comes in three flavors POP1, POP2, and POP3 the number denoting the different version number of the protocol. IMAP is an alternate mail protocol that allows the client email programs to view the mail messages directly on the mail server without downloading.

Proxy -A type of firewall that relays requests and responses between clients on a secure internal network and servers on an untrusted network. The proxy server hides the internal network by breaking the TCP/IP connection. Hosts outside your network perceive the proxy server as the source of the communication.

Router - A network device that directs (routes) TCP/IP traffic to its destination.

Server Side Applications - A class of applications that run on a Web server that create HTML pages with dynamic content, process forms from browsers, retrieve/store data from databases, and other functions. Server side applications are typically written using PERL, C/C++, Java, Visual Basic or other ASP tools.

SET - (Secure Encryption Technology) Architecture for protecting credit card transactions across the Internet.

SSI - (Server Side Include) A Web server technique for inserting dynamic content to an otherwise static HTML page. Examples include counters, time stamps.

SMTP- (Simple Mail Transfer Protocol) - Protocol used by computers use to send mail to each other over the Internet.

SOCKS - A type of firewall that transports TCP/IP traffic through a secure gateway. A SOCKS server performs many of the same services that a proxy server does, without the double connections. Requires SOCKS code be run on client.

Sockets - A programming method for connecting applications across a network. Used by Web applications as a way to access databases. See also ODBC, JDBC

SSL - (Secure Sockets Layer) – A Web encryption protocol that provides a private channel between two communicating applications to insure privacy of data, partner authentication, and integrity.

TCP/IP- (Transmission Control Protocol) The communications protocol used by the Internet.

URL- (Uniform Resource Locator) - This is a global term for a "place" or a "file" that can be accessed on the Internet. Most people are familiar with the "http" form as in http://www.ibm.com Other URL forms include "mailto," "news," "file", "telnet," "gopher," and "ftp."