Internet Services and Addresses

Internet Services and Addresses

Aside from being hypertext-based and capable of transferring a number of multimedia file formats, the Web is unique in its ability to access other Internet services. Being the youngest of the Internet services, the Web can access all of its older siblings, including Internet e-mail, UseNet newsgroups, Gopher servers, and FTP servers. Before we can access these services, though, we need to know what they do and how their addressing schemes work.

Internet E-mail

Internet e-mail is designed for the transmission of ASCII text messages from one Internet user to another, specified user. Like mail delivered by the U.S. Post Office, Internet e-mail allows you to address your messages to a particular person. When sent, it eventually arrives in that person's e-mail box (generally an Internet-connected computer where he or she has an account) and your recipient can read, forward, or reply to the message.

Internet e-mail addresses follow a certain convention, as follows:

username@host.sub-domain.domain.first-level domain

where username is the name of the account with the computer, host is the name of the computer that provides the Internet account, sub-domain is an optional internal designation, domain is the name assigned to the host organization's Internet presence, and first-level domain is the two- or three-letter code that identifies the type of organization that controls the host computer.

An example of a simple e-mail address (mine) is tstauffer@aol.com, where tstauffer is the username, aol is the domain, and com is the first-level-domain. com is the three-letter code representing a commercial entity. This e-mail address describes my account on the America Online service, which is a commercial Internet site.

First-level domain Organization Type

.com Commercial

.edu Educational

.org Organization/Association

.net Computer Network

.gov Government

.mil Military Installation

.ca Canadian

.fr French

.au Austrailian

.uk United Kingdom

.jp Japanese

You may have also noticed that my address doesn't include a host name or a sub-domain. For this particular address, it is unnecessary because America Online handles all incoming Internet e-mail through a gateway. Once it receives the e-mail, it may indeed send it to another computer within its online service, but this is an internal operation that doesn't require a specified host in the Internet address.

Consider todd@lechery.isc.tamu.edu. This is an address I had a few years ago when I worked at Texas A&M University. (I no longer receive e-mail at this address.) Notice how it uses all of the possible parts of an Internet address. todd is the username, lechery is a host computer (in this case, an actual, physical computer named "lechery"), isc is a sub-domain name that represents the computers in the Institute for Scientific Computation, tamu is the domain name for all Internet-connected computers at Texas A&M University, and edu is the three-letter code for educational, which is the type of organization that Texas A&M is considered to be on the Internet.

UseNet Newsgroups

The next Internet service we'll talk about is UseNet newsgroups. These are the discussion groups on the Internet, where people gather to post messages and replies on thousands of topics ranging from computing to popular entertainers, sports, dating, politics, and classified advertising. UseNet is a very popular Internet service, and most Web browsers have some built-in ability to read UseNet discussion groups.

Like Internet e-mail, UseNet discussion groups have their own system of organization to help you find things. This system uses ideas and syntax that are similar to e-mail addresses, but you'll notice that UseNet doesn't require that you find specific hosts and servers on the Internet-just a particular group. UseNet newsgroup names use the following format:

first-level name.second-level.third.forth...

The first-level name indicates the type of UseNet group this is, the second narrows the subject a bit, and the address continues on until it more or less completely describes the group. For instance, the following are both examples of UseNet newsgroup addresses:

co.general

comp.sys.ibm.pc.misc

Gopher and WAIS

Gopher has been described as the poor man's Web, and it's definitely true that Gopher is a precursor to some of the Web's capabilities. Gopher is a system of menu items that link sites around the world for the purpose of information retrieval. This isn't a hypertext system like the Web, but it is similar to the Web in that it's designed for document retrieval.

While Gopher can only offer access to text files and allow you to download files using the FTP protocol, it is still used occasionally by academic, government, and similar sites. Fortunately, your Web browser can easily offer Gopher access too, so there's no need to have a separate application.

FTP

The File Transfer Protocol (FTP) is the Internet service that allows computers to transfer binary files (programs and documents) across the Internet. This is the uploading/downloading protocol that you might use to obtain copies of shareware or freeware programs, or that might be useful for downloading new software drivers from a particular computer hardware company.

Using a model identical to the Gopher system, FTP addresses use the following format:

host.sub-domain.domain.first-level domain