Eastern Region Training and Applications Note No. 11
ER TAN-11
A WORLD WIDE WEB PRIMER
National Weather Service Forecast Office
Albany, New York
Scientific Services Division
Eastern Region Headquarters
Bohemia, New York
March, 1997
Mention of a commercial company or product does not constitute an
endorsement by NOAA/National Weather
Service, Eastern Region. The use of this information from this
publication for publicity or advertising
purposes is not authorized.
1. INTRODUCTION
This Paper will provide a general guide and introduction to the
Internet, especially the World Wide
Web (WEB). The Internet is a rapidly expanding, universal
communications and information network. Located
within the Internet is the WEB which is becoming the most commonly
used application of the Internet. The WEB
has become increasingly popular because it is extremely user
friendly. Through the use of a mouse you can
navigate throughout the world on the WEB. Its ability to use and
display impressive graphics, its increasing
capability to display multimedia information, its ability to
incorporate application programs, and finally,
its ability to adapt will lead to the WEB's continued expansion and
acceptance (December and Randall 1995).
Due to the large and time-dependant nature of meteorological
data, a convenient means for the
transmission and acquisition of data is needed. The Internet and
especially the WEB offer a relatively
reliable, cost effective, and easy means to share and receive large
quantities of meteorological information.
The WEB contains an incredible amount of material on other subjects
as well. Becoming proficient in
utilizing the WEB and its resources will enable the user to search,
receive, and exchange vast amounts of
information.
2. THE INTERNET
The Internet was conceived during the 1960's by the U.S.
military as an efficient and reliable method
to maintain communications during or after an enemy attack. The
original network was given the name ARPAnet
for the Advanced Research Projects Agency of the U.S. military which
developed it. During the next several
years, an increasing number of research institutions and universities
began to connect to this network.
Because of this, the military organized a second network called
MILnet to concentrate on military
communications alone. During the 1980's the National Science
Foundation established the NSFnet. This network
linked several supercomputer centers and began to take over the
ARPAnet, eventually leading to the Internet.
In 1991, the U.S. High Performance Computing Act established the
National Research and Education Network
(NREN). NREN then proceeded to expand and maintain the NSFnet. NSFnet
has become the high speed, high
capacity network for research, education, and commercial purposes
that we now call the Internet (December and
Randall 1995). The Internet can be utilized by all sorts of
applications including E-mail, Telnet, FTP, and
WEB browsers. Its purposes include education, communication, commerce
and entertainment.
The World Wide Web is just one way of accessing this massive
Internet network. The WEB features an
easy to use method to navigate through the enormous world wide
network. The WEB encompasses a vast amount of
real time, research, reference and general meteorological
information, as well as information on nearly any
other subject. The World Wide Web offers a tremendous potential for
research and professional development.
3. GETTING CONNECTED
a. Connecting directly to the Internet
There are quite a few ways to connect to the Internet. Probably
the most logical way is through a
direct connection. This involves having a dedicated, high capacity
line that connects your computer to the
Internet. If you have direct access to the Internet through an
educational institution or commercial service,
the process is quite simple. All that it involves is plugging in the
hardware, connecting the communication
line, and configuring your system.
Connecting directly to the Internet provides an unlimited
potential for exploration and development.
One of the most obvious capabilities is the potential to have your
own WEB server. The Scientific
Applications Computer (SAC), available at most NWS offices, is a
good candidate to use in WEB exploration
and development. The SAC is the cornerstone of the SOO/SAC Program, a
NWS program providing the Science and
Operations Officer (SOO) at each NWS Weather Forecast Office with
tools for on-station research, training,
and professional development (Bruehl 1996). Instructions on
connecting the SAC to the Internet (see Bruehl
1995a) are available on-line from the SOO/SAC Homepage at:
http://www.comet.ucar.edu/pub_html/sac_html/README/ internet.html.
b. Connecting via a dial-up connection
If you do not have a direct Internet connection, selected
software options allow you to perform many
WEB tasks, such as browsing and other applications, through a dial-up
connection. To ensure the brevity of
this document, instructions for setting up such a program have not
been included. However, more information
can be found at: http://www.morningstar.com.
c. Connecting via an Internet access provider
Connecting via an access provider is easily done through UNIX,
DOS, and other platforms. Access
providers grant Internet connectivity by dialing into their system as
well as other connection methods. Once
connected to their system, it is easy to exchange files, connect to
other Internet hosts, and perform most
other common Internet tasks. Access providers are easily found in the
computer world. There are the familiar
national providers such as America On-Line and Compuserve as well as
numerous local providers. They often
supply all of the software needed including the dialing and
connecting software as well as the WEB browser
itself.
4. SERVERS
a. Finding Space for WEB Pages
The WEB server is a program that enables you to distribute WEB
pages directly off a machine. To have
a presence on the WEB you will need the capability to produce and
display information on-line via a WEB
server. If you do not operate a WEB server, you will need to gain
access to one. Finding a host to keep your
WEB files is not that difficult. There are several ways one can
obtain space on a system with a server.
Organizations with existing servers often allow the use of their
space for free or for a small fee. Some
Forecast Offices, River Forecast Centers, and even Regional Offices
may allow you to use space on their
server. Local government and non-profit organizations often provide
use of space on their server at no cost
if you provide information that is of service or value to the
community.
Another possibility is to use a commercial service. Many
commercial Internet access providers offer
low rates and sometimes free space on their server. Low rates are
usually easy to get if you are providing a
public service or displaying quality products that are sought after
by the public. These providers may even
compete for your services since they can boast that they have your
service on their system. Many educational
institutions will allow you to use their server at no cost if you
have some affiliation with them. If your
proposed project is in harmony with their goals they will likely want
you to come aboard. High quality
content is a valuable product in the academic WEB-world (Proudfoot
1996).
5. WEB BASICS
a. WEB Addresses
The Internet has its own method of identifying users, servers or
other entities. The Uniform Resource
Locator (URL) and Uniform Resource Identifier (URI) are the
addressing system for the Internet. The following
discussion of the structure of the Uniform Resource Locator is based
on the on-line documents A Guide to
URL's (see Baker 1995) and HTML Reference Manual (see Hannah 1996).
The URL consists of four basic parts identified by the letters
a, b, c, and d as follows:
aaaa://bbb.bbb.bbb/ccc/ccc/ccc?ddd
1) The aaaa is the part of the URL that specifies the access
method. The access method defines which
mechanism is used to communicate and connect with the particular
Internet resource. There are numerous
mechanisms including telnet, gopher, news, and http.
The acronym http stands for HyperText Transfer Protocol and this
access method is used exclusively
with the World Wide Web. It requires the presence of a program
running on the destination computer, called a
WEB server, that understands and responds to this protocol.
For example, The URL of the NWSFO Albany's World Wide Web site
is: http://nwsfo.atmos.albany.edu/www/wx.html. Note the http
which signifies the site is accessed through
HyperText Transfer Protocol.
2) The second part of the URL, indicated by the "b's," is the
fully qualified name of the computer
running the WEB server. It can be divided into three parts: the
machine name, the sub domain name, and the
domain name. More information on URL's and hostnames is available
on-line at
http://www.ncsa.uiuc.edu/demoweb/url-primer.html.
For example, the fully qualified name of NWSFO Albany's machine
on the Internet is
nwsfo.atmos.albany.edu. The name of our machine is nwsfo. It is
located on the atmos.albany sub-domain, which
is the node at the Atmospheric Science Department of The State
University of New York at Albany. Notice the
edu, which is the domain type for an educational organization. The
fully qualified name is synonymous and
interchangeable with the Internet Protocol or IP address. The IP
address is simply a unique set of four
groups of numbers which is used in the actual addressing process.
For example, Albany's IP address is
169.226.4.35.
3) The third part of the URL, designated by the "c's," is the file
path. It is the path name of the
file to be retrieved, including the directories, subdirectories, and
filename.
For example, The URL of the NWSFO Albany's World Wide Web site
is: http://nwsfo.atmos.albany.edu/www/wx.html. The file path
/www/wx.html comes after the node. It includes the
www directory and the filename wx.html.
4) The last part of the URL, designated by the "d's," signifies
arguments which are used for specialized
processes. Depending upon the access mechanism and the file being
accessed, extra characters can follow the
file name. They are separated by predefined special characters, such
as: #, ?, and &.
b. Acquiring a WEB Browser
The WEB browser allows retrieval of the HyperText Markup
Language (HTML) file, which is the basic
file type of the WEB. The browser also allows the retrieval of many
other file types including graphic,
sound, animation and multimedia files. WEB browsers are available for
nearly every kind of computer platform.
Commercial versions are available for free or at relatively
inexpensive prices. The three most popular
Internet browsers are Internet Explorer from Microsoft Corp.,
Netscape from Netscape Inc., and MOSAIC from
the National Center for Supercomputing Applications (NCSA).
c. WEB Pages
WEB pages are written in the HyperText Markup Language (HTML).
HTML is composed of a set of elements
that enhance and determine the display of a simple text document.
There are numerous versions of HTML, each
new version is usually an expanded version of an older one. Different
browsers and different versions of a
particular browser allow different versions of HTML to be read with
nearly all browsers capable of reading
the earliest versions of HTML. Descriptions of the most commonly
used elements and features are avialable in
on-line documents. Two that are recommended include HTML Quick
Reference available at:
http://kuhttp.cc.ukans.edu/ lynx_help/HTML_quick.html (see Grobe
1995) and HTML Elements List available at:
http://www.sandia.gov/sci_compute/elements.html (see Hannah 1995). It
is important to keep in mind that HTML
is an evolving language, and different WEB browsers may recognize
slightly different sets of HTML elements.
d. WEB Browser Basics
The following list contains some of the most commonly used
features or tools associated with
WEB browsers, which are often located on the browser as a button. The
most used frequently used features
listed below were compiled with help from The Mosaic Handbook (see
Dougherty et. al. 1994).
Open:
Use the open feature to go to a particular site or Home Page on
the WEB. To do this, click and hold
down the left mouse button on File, then move down to Open URL and
let go of the mouse button. A window will
open, and then click the left mouse button inside the input window
and type the URL of your choice.
Open File:
This will allow you to view a file that is located on your local
system through the WEB browser. This
is handy when you are creating an HTML file and you wish to view it
before placing it on a server.
Back:
This button will take you back to the last location in which you
moved forward from.
Forward:
This button will move you forward to the last location you moved
back from.
Reload:
This button will reload the most recent version of the URL in
which you are located at. This is
useful when the page may have loaded improperly or if the page
changes frequently and you need to view the
most recent version.
View Source:
This button will allow you to view the source code which is the
actual HTML file. To view the source
code, simply click on the view pull-down menu and select view source.
This will open up another window
containing the source code in HTML. This is a good feature if you are
curious to see how a WEB author created
or setup a particular WEB page. It's very handy for the beginning WEB
author.
Hot List, Bookmarks or Favorite Locations:
After you find a URL of interest you can add it to your Hot
List, Bookmarks or list of Favorite
Locations. These different names refer to the same type of feature;
the ability to compile a list of the WEB
sites that you find most interesting and visit most frequently. By
using this feature, you will not have to
remember the often lengthy, specific URL address; instead, you can
just click on the name of your favorite
location.
Home Document:
If you do not want to return to the default Home Page each time
you start up your browser,
the Home Page option is adjustable. Refer to the Help menu for more
information.
Help:
The Help feature will provide additional information on common
questions and features regarding the
WEB browser.
e. Meteorological Information
There are numerous sources of real time, reference and research
related meteorological material
available on the WEB. An easy way to locate meteorological and any
other information is to use search
engines such as Yahoo, Web Crawler or Lycos. Search engines are WEB
sites that allow you to enter keywords on
a particular subject, and generate a list of addresses which include
information regarding those subjects. A
few suggested WEB sites include:
NWSFO Albany, NY..... .....
http://nwsfo.atmos.albany.edu
NOAA Home Page..... ..... http://www.noaa.gov
National Weather Service Home Page.......... http://www.nws.noaa.gov
Office of Industrial Meteorology..... .....
http://www.nws.noaa.gov/im/index.html/
The SOO/SAC Home Page..........
http://www.comet.ucar.edu/pub_html/sac_html/index.html
Yahoo ..... ..... http://www.yahoo.com
University WEB Sites..........
http://www.unidata.ucar.edu/community/community.servers.html/
6. SUMMARY
This training and applications note contains a general
introduction to the Internet, particularly the
World Wide Web. The WEB encompasses a vast amount of real time,
research, reference, and general
meteorological information as well as enormous amounts of information
on nearly any subject. The World Wide
Web offers a tremendous potential for community outreach and for
public relations. In addition, the WEB
offers an easy way to acquire and display large amounts of
meteorological and other types of data, including
text and graphics products. The possibilities are unlimited and it's
now easier than ever to become a member
of the on-line community. The best way to learn about the WEB is to
explore it.
REFERENCES
Baker, D. W., cited 1995: A Guide to URL's. [Available on-line from
http://www.netspace.org/
users/dwb/url-guide.html.]
Bruehl, P., National Weather Service-Office of Meteorology, cited
1995a: Connecting your SAC to
the Internet. [Available on-line from
http://www.comet.ucar.edu/pub_html/sac_html/README/
internet.html.]
_____, P., National Weather Service-Office of Meteorology, cited
1995b: How to Access and
Download Mosaic from NCSA. [Available on-line from
http://www.comet.ucar.edu/pub_html/ sac_html/
README/mosaicget.html.]
_____, P., National Weather Service-Office of Meteorology, cited
1996: SOO/SAC Home Page.
[Available on-line from http://www.comet.ucar.
edu/pub_html/sac_html/index.html.]
December, J., and Randall, 1995: The World Wide Web Unleashed.
Sams.net Publishing,
1346 pp.
Dougherty, D., R. Koman, and P. Ferguson, 1994: The Mosaic Handbook.
O'Reilly & Associates, INC., 262 pp.
Grobe, M., Academic Computing Services, The University of Kansas,
cited 1995: HTML Quick
Reference. [Available on-line from
http://kuhttp.cc.ukans.edu/lynx_help/
HTML_quick.html.]
Hannah, M. J., Sandia National Laboratories, cited 1995: HTML
Elements List [Available
on-line from http://www.sandia.gov/sci_compute/elements.html.]
_____, M. J., Sandia National Laboratories, cited 1996: Uniform
Resource Locator (URL)
[Available on-line from
http://www.sandia.gov/sci_compute/html_ref.html.]
Proudfoot, B., cited 1996: Finding a WWW Host for Your Project
[Available on-line from
http://www.ucsc.edu/civil-war-letters/host.html.]