rfc1941.html

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

in the school should they be located?</H4>
<P>
You should make Internet access possible for as many of your school's
computers as possible. Ideally, you have computers located throughout
the school - in classrooms, the library, and laboratories - and they
are all connected together with printers and other peripherals in one
or more LANs. In that case, you acquire one dedicated Internet
connection of 56 Kbs (Kilobits per second) or higher to serve the
whole school.
<P>
If your budget and existing computer equipment are both limited, you
can use a dial-up service and a modem to access the Internet, but in
most cases that will only be viable for one computer at a time. As
use of the Internet catches on in your school, it will eventually be
more effective for you to create the LAN with Internet access
mentioned above than to keep adding modems in classrooms.
<P>
If you must choose between Internet access in one lab in the school
or Internet access for the same number of computers throughout the
school, in order to get teachers to use the access you must make it
available where they can most easily take advantage of it. This
usually means that you make access available throughout the school.
Although a computer lab is an easier maintenance set-up for the
person in charge of keeping the equipment running and allows each
individual (or pair) in an entire class to be using a computer at the
same time, a computer located in the classroom is more convenient for
both the teacher and the class. Internet resources can be more easily
integrated into a classroom lesson, and the emphasis remains on using
the Internet as an instructional tool. Since only one or two
computers can usually be placed in each classroom, teachers will
learn to allocate computer time creatively. And if you are able to
provide only a few computers throughout the school, make sure that at
least one of them is in the library where all students will have the
chance to be exposed to the Internet as a resource.
<P>
Networking all computers campus-wide can be expensive. You may want
to investigate initially giving one lab, the library, and a few
classrooms dial-up access, assuming phone lines are available. Even a
connection to only one classroom as a demonstration may help you to
garner more support for creating a campus-wide local area network
that is routed to the Internet through a dedicated line.
<P>
<A NAME="4.7"></A>
<H4>4.7  Can people get on the Internet from home?</H4>
<P>
This depends on your network access provider. It is certainly a
possibility and is definitely desirable for the educators at your
school.  To make it possible for teachers and other staff to dial in
to the school network (and then out to the Internet) from home, you
will need to employ, at the least, multiple phone lines and modems.
Talk to your service provider about other technical requirements.
<P>
Many teachers like to be able to learn at home as well as on school
grounds, and having the ability to explore when they have the time is
invaluable. One school district we know of made low-interest loans
available to teachers so that they could buy home computers. When the
technology was later made available in their classrooms, they already
had some experience and were comfortable beginning to use it in
day-to-day instruction.
<P>
The question of whether or not to make the option to dial in from
home available to students is more difficult. On one hand, a school
may not be able to escape the idea that it is responsible for how
students use the Internet access it provides, even though the school
has no control over the home environment. On the other hand,
particularly in high school, much schoolwork is done at home. Since
most classrooms don't have enough computers for all students to
access the Internet at once, it is even more likely that work will
not be completed during class time. Having Internet access from home
becomes more important.
<P>
Discussion of whether or not you want to make this option available
to students - even if it is technically possible - should involve as
many school partners as possible, including faculty, administration,
parents, and other community members. It might take place in a public
forum such as a school/community meeting.
<P>
<A NAME="5"></A>
<H3>5.  Questions About Using Internet Services</H3>
<BR><A HREF="#toc">Return to Table of Contents</A>
<P>
The way to find people, information, software, and anything else on
the Internet is generally to use either printed or electronic guides
and Internet services. In this section we will concentrate on the
services.  (See <A HREF="#6">Section 6, "Questions about Classroom Resources,
Projects, and Collaboration,"</A> for information on guides.) We answer
more questions about the World Wide Web than about other online
services for three reasons.  First, the World Wide Web is the
Internet tool coming into most prominence at the time of this
writing. Second, many (if not all) of the other services are included
seamlessly in the Web; that is, they're there, but you may or may not
realize you're using them. Third, making your way around the Internet
using the World Wide Web is easy; for people not interested in
computers, access to the Internet has become less frustrating.
<P>
This is not to say that finding what you want is always simple. The
Internet is like a vast library without a comprehensive card catalog.
New ways to do indexing and searching are being devised and employed,
and you'll need some time to learn how to use them.
<P>
<A NAME="5.1"></A>
<H4>5.1  What is the World Wide Web?</H4>
<P>
The World Wide Web (WWW) is a project initiated by the European
Laboratory for Particle Physics (CERN) located in Geneva, Switzerland
and currently driven by the World Wide Web Consortium. When exploring
the World Wide Web, users navigate through documents by selecting
highlighted text that leads to another document or location. The
highlighted text can be called a "pointer," a "link," or an "anchor."
This navigation results in a three-dimensional exploration of
documents instead of a flat text document. The World Wide Web
incorporates different media into its documents, including text,
sound, graphics, and moving images.
<P>
The World Wide Web presents either a graphical or a text interface to
numerous Internet resources. Not only can users access documents
specifically designed for the Web, they can also view documents on
Gopher servers, use FTP to download files, and launch a telnet
session. Some World Wide Web clients also allow for the use of email
and Usenet news.  This is an easy-to-use, nonthreatening way to
approach the Internet, and does not require in-depth technical
knowledge. (See <A HREF="#5.5">Question 5.5</A> for a discussion of these 
other
services.)
<P>
<A NAME="5.2"></A>
<H4>5.2  How do I connect to the World Wide Web?</H4>
<P>
First, you will need at least a SLIP or PPP connection. (See <A 
HREF="#4.1">Question
4.1</A> for more information; SLIP or PPP is the "advanced individual
user" solution described there.) Accessing the Web is like using any
other service on the Internet: you run a client on your computer
which accesses a server, in this case a Web server, running on
another computer. In Web terms, the client is called a browser. The
browser retrieves and reads documents from Web servers. Information
providers establish Web servers for use by network users, and when
you become proficient at using the Internet, you may want to become
exactly that kind of information provider.
<P>
Most Web browsers share common features. One feature is the hotlist,
or bookmark. This allows you to mark your favorite sites. Your
browser will store these sites and their addresses and allow you to
revisit them later by simply selecting the name of a site from a
menu. Another feature common to most browsers allows you to save the
current file to your local disk.  Some browsers keep a tally of the
sites you've visited recently and allow you to revisit them without
typing in the location again. Every browser is different, so it pays
to explore your own client software and learn its features through
practice. Most people, even those with little computer experience,
find that it's easy to learn to use a browser just by exploring on
their own.
<P>
Each document contained on Web servers across the Internet has a
unique address. This is called a URL, a uniform resource locator.
Browsers negotiate URLs just like mail software negotiates email
addresses. Users can type in the URL for the browser to access. URLs
are also embedded in a Web document's text, providing a seamless link
to another location or document.
<P>
<A NAME="5.3"></A>
<H4>5.3  How is the World Wide Web linked?</H4>
<P>
The Web functions as a distributed hypermedia system. The purpose of
this system is to allow the exchange of information across the
Internet in the form of hypertext documents called Web pages or home
pages. Hypertext is text with pointers or links to further
information in various formats (text, graphic, video), allowing you
to branch off to another document for more information on a given
topic, and then return to the same location in the original document
with ease. Pointers in a Web document are analogous to HyperCard
stacks or Microsoft help files in which you click on an option (a
pointer or a link) and the program moves you to another document, or
location.
<P>
Documents published on the Web are constructed in hypertext markup
language, or HTML. This is a simple language that allows you to
format text, insert images and sound, and create links in a document.
Tutorials on creating Web services are available at the NCSA Mosaic
Home Page, the automatic starting place for Web exploration when
using the Mosaic client.  There are also Web page creation resources
listed in <A HREF="#9">Section 9, "Resources and Contacts."</A>
<P>
<A NAME="5.4"></A>
<H4>5.4  Where do I get a World Wide Web browser?</H4>
<P>
The two most common graphical Web browsers at the time of this
writing are Netscape and Mosaic. Netscape is a commercial product but
is currently free for educational use. Mosaic is free.  Both of these
packages are available for Macintosh, PC, and Unix platforms through
the Internet. See <A HREF="#9">Section 9, "Resources and Contacts,"</A> 
for details.
<P>
For those users with lower-speed connections that cannot accommodate
full graphical browsers, there is a text-based browser available for
Unix systems called Lynx. A public-access Lynx client is accessible
through telnet at the server of the World Wide Web Consortium, which
is listed in <A HREF="#9">Section 9, "Resources and Contacts."</A>
<P>
Many commercial online services, such as CompuServe, Prodigy, and
America Online, include a Web browser as part of their offerings.
More and more often, Web browsers are being included as part of the
standard connection software provided by the Internet Service
Provider.
<P>
<A NAME="5.5"></A>
<H4>5.5  What are the other services on the Internet?</H4>
<P>
There are a number of other services to help you get around on the
Internet. The most common ones are described here. For more
information, see "EFF's (Extended) Guide to the Internet" by the
Electronic Frontier Foundation, and "The Whole Internet User's Guide
and Catalog" by Ed Krol, both of which are listed in <A 
HREF="#reading">Section 8,
"Suggested Reading,"</A> in addition to the Glossary entries mentioned
for each tool.
<P>
<B>Email.</B>  Email is probably the most basic tool on the Internet. It is
short for electronic mail and may be used in a couple of ways. You
can send messages back and forth with just one person, or you can
participate with a group of people who discuss topics of common
interest. These groups are called mail lists. You join and leave the
lists by sending email to one address, and you post messages to all
the people on the list by sending email to a slightly different
address. Sometimes a human does the list registration and sometimes a
software program does it. For more information see the entries for
email and mailing lists in the Glossary.  A list of mail lists
related to primary and secondary education can be found in <A 
HREF="#9">Section 9,
"Resources and Contacts."</A>
<P>
<B>Network News.</B>  Also known as Usenet News or Net News. Reading news is
similar to joining an email list, but instead of the messages coming
to your mailbox, you use news reader software to read messages on a
computer where they are accumulated. For more information see the
entry for Usenet News in the Glossary.
<P>
<B>FTP.</B>  FTP stands for File Transfer Protocol, and just as the name
implies, it allows you to transfer files from one computer to
another. It is the name for both the protocol and the program. A
special kind of FTP, Anonymous FTP, allows you to access the many
public archives on the Internet. FTP is not used by itself as much as
it used to be, since people often use Web browsers and Gopher clients
which incorporate FTP when they want to retrieve files. For more
information see the entries for Anonymous FTP and FTP in the
Glossary.
<P>
<B>Telnet.</B>  Telnet allows you to log into a computer somewhere else on
the Internet and use the services there. For example, if you don't
have a Gopher client or a Web browser, there are some public access
sites that you can telnet to in order to use a Gopher client or a
text-based Web browser.
<P>
<B>Gopher.</B>  Gopher is a tool that lets you browse for information on the
Internet using menus. If you know what you're looking for and have an
idea about where to find it, Gopher can make your search easier. And
when you have located something of interest, whether it's a document,
a data set, or a picture, Gopher will retrieve it for you. For more