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Figure 1-3.—Example of a telefax address label. | Up
Aerographers Mate, Module 04-Environmental Communications and Administration | Next
Figure 1-5.—Various layers of the Internet. |
COMPUTER NETWORKS
The latest and fastest growing method of
disseminating environmental information is through
the use of computer networks. The advent of the
information revolution has brought dramatic changes to
the METOC community. Aerographer’s Mates must
now be proficient in accessing and transferring
information in an automated environment. Almost all
METOC activities, including those aboard ship, have
access to some type of computer network.
A computer network consists of two or more
computers connected for the purpose of exchanging
messages and sharing data and system resources. A
local area network (LAN) connects personal computers
and workstations (each called a node) over dedicated,
private communications links. A wide area network
(WAN) connects large numbers of computers (nodes)
over long distance communications links, such as
common carrier telephone lines. An internet is a
connection between networks.
The Internet
The Internet is a WAN that connects thousands of
different networks all over the world, enabling anyone
with a computer and Internet access to transmit and
retrieve information worldwide. The Internet is not
owned or funded by any one institution, organization, or
government. It was originally developed by the
Department of Defense in the late 1960’s as a reliable
communications network that, because of its simple
design and versatility, could survive a nuclear attack.
Gradually, other government agencies, universities,
and scientific organizations began to tap into the
network. By 1983, newer networking protocols were
developed, laying the foundation of the Internet we use
today.
The development of Hypertext Markup Language
(HTML) in 1990 significantly increased speed and
capacity, and enabled users to transmit graphical
information over the Internet for the first time. As an
additional feature, HTML created the ability to insert
hypertext links into a document. Hypertext links allow
a user to load another document into their computer
simply by clicking on an on-screen "link" from the
current document. Subsequently, a huge hypertext
network known as the World Wide Web (WWW) came
into being in 1992. These developments enabled any
individual or organization to create their own "website",
and thus disseminate information over the Internet.
Each website normally has an index or introductory
document commonly referred to as a "homepage."
The Internet consists of several networks linked
together via Internet Service Providers (ISPs) that use
high-speed digital and fiber optic circuits. Each
computer (client) must be connected to an Internet hub,
known as a sewer. Servers are fast computers that are
connected to the Internet full-time. They are located at
different sites throughout the world, and direct Internet
traffic to its proper destination. Today, the term
"Internet" is used to refer to the physical structure of the
Net, including client and server computers and the lines
that connect them (fig. 1-4). The term "World Wide
Figure 1-4.—The Internet.
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