rfc1941.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

      contractors.

      Questions for Internet Service Providers furnishing dial-in
      service:

      There are some specific questions you should ask of an ISP who is
      providing dial-in connections. (See Question 4.7 for a further
      discussion on dialing in from home.)

      What is the charge per minute for connectivity?

      Is SLIP or PPP connectivity available?

      Will the ISP be providing software which allows you to use
      Internet services such as email and the World Wide Web or will
      they help you obtain it?

      Will they help you install it?

      Ask for references of other clients using dial-in service and when
      you check them, one of the questions to ask other customers is if
      they encounter lots of busy signals. (You can also check this
      yourself by trying the access provider's dial-in number at various
      times during the day. Just dial it by phone and see how many busy
      signals you get.)

4.6  How many of our computers should have Internet access and where
     in the school should they be located?

   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.

   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.



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   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.

   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.

4.7  Can people get on the Internet from home?

   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.

   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.

   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



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   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.

   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.

5.  Questions About Using Internet Services

   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 Section 6, "Questions about Classroom Resources,
   Projects, and Collaboration," 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 and has become less frustrating.

   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.

5.1  What is the World Wide Web?

   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.

   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



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   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 Question 5.5 for a discussion of these other
   services.)

5.2  How do I connect to the World Wide Web?

   First, you will need at least a SLIP or PPP connection. (See Question
   4.1 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.

   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.

   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.

5.3  How is the World Wide Web linked?

   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



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   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.

   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 Section 9, "Resources and Contacts."

5.4  Where do I get a World Wide Web browser?

   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 Section 9, "Resources and Contacts," for details.

   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 Section 9, "Resources and Contacts."

   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.

5.5  What are the other services on the Internet?

   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 Section 8,
   "Suggested Reading," in addition to the Glossary entries mentioned
   for each tool.

   Email.  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