WWW 2

In the last lesson I told you that "URLs" is pronounced "earls." In fact, a lot of people still use the initials and call them "U-R-Ls." I personally prefer calling them "earls" because "earls" rhymes with "squirrels," but the choice of what you call them is completely up to you :)

Let's take a look at how a sample WWW browser works. There are three basic types of WWW browsers available: line-mode browsers, full screen browsers (like Lynx), and graphical browsers (like Mosaic).

Line-mode browsers are about as user un-friendly as you can get. This is hard to describe, but line-mode browsers work a little like FTP inasmuch as you type a command, get some information on your screen, type a new command, get some more information, and so on ...

A full screen browser puts a menu on your screen that looks a little like the Gopher menus that we saw in MAP18: Gopher (Part One). You move the cursor up and down the screen, select a highlighted link, press enter or return, and you are automatically taken to a new document or file (your fill screen browser may work differently than this, though).

Graphical browsers allow you to access not only text, but also pictures and sound (a.k.a. "hypermedia"). In fact, these pictures can be put in Web documents (a.k.a. Web pages), making that Web page look less like a Gopher menu and more like a page from a color magazine! Most graphical browsers use a mouse, and you point-and-click on a highlighted link to access it.

The URL for the sample Web page that we are going to use in this lesson is

    http://ua1vm.ua.edu/~vmhttpd/index.html
and I am going to be using the UF WWW Browser for CMS to access this page. I'll talk a little more about how you can access a WWW browser in a few minutes, but I first want to show you what a basic Web page looks like.

The UF WWW Browser for CMS is the browser that my service provider uses, and it is a full screen browser. The browser that you use -- if you can even access a WWW browser -- will probably look and work a little differently than what you will see in this example.

Finally, in real life my browser highlights the links by making them a different color than the rest of the text. There is no way for me to use different colors in this letter, so I have highlighted the links in this example by surrounding them with a (* *).

Just like I can access an item in a Gopher menu by pointing at it and selecting it, I can access a WWW link by pointing at it and selecting it.

Enough talk. Time for the example.

I access my provider's WWW browser, and the following appears on my screen:

     Albert 1.2.0 (UF WWW Browser for CMS)    Screen 1 of 2 (more screens)

Viewing=http://ua1vm.ua.edu/~vmhttpd/index.html
Title=UA1VM WWW Home Page
Welcome to The University of Alabama's CMS WWW Server

This CMS server is still under development. Any (*comments*)
or (*suggestions*) will be greatly appreciated. Thank you.

Gopher Sites:
- (*UA1VM CMS Gopher Server*)
- (*UA1IX AIX/370 Gopher Server*)
- (*RISC/6000 Gopher Server*)
- (*RICEVM1 CMS Gopher Server*)
Telnet Sessions:
- (*UA1VM.UA.EDU*)
- (*UA1IX.UA.EDU - Line Mode*)
- (*RISC.UA.EDU - Line Mode*)
WWW Sites:
- The University of Alabama Libraries (*WWW*)
- The University of Illinois at Urbana-Champaign (*WWW*)
- The Alabama Supercomputer Network (*WWW*)
- NASA Information Services via (*WWW*)
Leisure:
- (*Intertext Magazine*) - Electronic Fictional Magazine at The
University of Michigan
- (*Wiretap*) - a gopher to Cupertino, California
- (*NNR*) - UA1VM's Network News Reader
Other Neat Stuff:
- The University of Alabama Library's On-Line (*Card Catalog*)
- a (*map*) of The University of Alabama campus
... snip snip snip ...
COOL!

I can select any of these links -- the words set apart from the rest of the text with a (* *) -- and be transported to that particular link.

>From this one Web page, I can access Gopher, telnet, and even other Web pages! (I can also access FTP, although this page does not show it).

We've seen a lot of Gopher and telnet recently. Let's take a look at another Web page. Since I used to be a Simulations Director at the United States Space Camp (did I forget to tell you that?), I'm going to move my cursor down to the (*WWW*) link next to "NASA Information Services", press enter, and see what happens:

     Albert 1.2.0 (UF WWW Browser for CMS)    Screen 1 of 2 (more screens)

Viewing=http://hypatia.gsfc.nasa.gov/NASA_homepage.html
Title=NASA Information Services via World Wide Web
National Aeronautics and Space Administration

NASA Logo

(*World Wide Web (WWW) information services*)

(*Hot Topics*) NASA news and subjects of public interest
(*NASA Strategic Plan*)
(*NASA Strategies, Policies, and Public Affairs*)
(*NASA Online Educational Resources*)
(*NASA Information Sources by Subject*)
... snip snip snip ...
This is certainly more interesting than SURAnet! ;)

>From this Web page I can access OTHER Web pages, and from those Web pages I can access even MORE Web pages, and so on ...

Yesterday I told you that it is possible for you to connect directly to a specific Internet resource so long as you know the resource's URL. How you do that depends on the browser that you use.

For the line-mode browser at CERN, for example, the command to connect to a particular URL is

    GO
replacing with the URL of the Internet resource that you want to access. In Lynx, you just select the "GO" link on the browser's start-up page; in most graphical browsers (like Mosaic), there is usually an "Open URL" option in one of the menus. (1)

Before you can do this, however, you have to first access the Web. There are three ways that you can do this:

  1. Through a browser stored on your local Internet service provider's machine. Ask your provider if your site has a Web browser, and how you can access it.

  2. Through a browser stored on your own machine. Until recently, you had to have a SLIP or PPP connection to do this. Some providers -- providers who FLOODED my mailbox when I did not talk about the special Level 2.0002746278546723 access that they offer -- now allow you to store a Web browser on your own machine even though you only have Level 2 access.

    If you do not have a SLIP or PPP connection, contact your provider BEFORE you store a Web reader on your own computer and double-check that your provider will support the browser. Most service providers can not support a Web browser unless you have a SLIP or PPP connection.

  3. Through a telnet connection to a publicly-accessible Web browser.
If you have a SLIP or a PPP connection, the WWW FAQ that I have stored on the University of Alabama's LISTSERV file server (WWW FAQ1) has a list of FTP sites where you can get specific Web browsers.

(Do me a favor ... re-read that last sentence. Did you EVER think you would understand a sentence like that? Isn't this workshop COOL?!!)

If you do not have access to a Web browser through your site, you may still be able to access a Web browser through telnet. The following are a few of the public Web sites: (1)

     telnet address            comments

-------------- -----------------------
info.cern.ch No password is required. This is in
Switzerland, so U.S. users might be
better off using a closer browser.

www.cc.ukans.edu The "Lynx" full screen browser, which
requires a vt100 terminal. Login as www.
Does not allow users to "go" to arbitrary
URLs.

www.njit.edu Login as www. A full-screen browser at
the New Jersey Institute of Technology.

sun.uakom.cs Slovakia. Has a slow link, so only use
from nearby.

info.funet.fi Login as www. Offers several browsers,
including Lynx (goto option disabled
there too).

fserv.kfki.hu Hungary. Has a slow link, so use from
nearby. Login as www.
Once you are on the Web, it is possible for you to do keyword searches (much like the Veronica searches we did in MAP21: Veronica) using one of the Web's many search engines. One of the best Web search engines is the WebCrawler. The WebCrawler's URL is
    http://www.biotech.washington.edu/WebQuery.html
and the WebCrawler searches for documents whose title AND CONTENT match your keyword.

Another Web search engine you probably will want to check out is the World Wide Web Worm. The Worm's URL is

    http://www.cs.colorado.edu/home/mcbryan/WWWW.html
The Worm is not at thorough as the WebCrawler, but it is still a pretty competent search engine.

Both of these search engines provide really good on-line help and instructions.

One last thing, and I am though for this lesson. Please remember:

  • The "Web" is the collection of all of the files and information that can be accessed by a Web browser.

  • Mosaic and Lynx and just BROWSERS that allow you to access the Web.

Posted bySumedh at 11:51 PM  

1 comments:

SBL-Geomatics said... December 15, 2008 at 3:37 AM  

Interesting scenario.Informative post. Thanks for sharing..
regards
Web Mapping services

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