If you want information about a term used in this course, you can probably find out about it by visiting The Free On-line Dictionary of Computing. For example, you can amaze your friends with up to date information about the World-Wide Web
This business of completing the first few letters of a command line and then executing the command at once is a bit dangerous. After all, you might forget what you last did with the command. For example, you might have typed latex extremely-long-file-name, but then typed latex some-other-file-name more recently. Then you might be surprised by having latex some-other-file-name executed, so it is safer to use the up arrow key to get back to commands that you have used recently. We take this up in a later class.
As it stands, our use of the image tag will not pass muster if we submit our HTML to the W3C HTML validator because we left out an important piece of the inline image tag (the <IMG> tag), namely, the ALT attribute. ALT is used to specify alternative text that the browser can show if for some reason the image cannot be displayed (for instance, if image display has been disabled by the user in order to speed downloads on a slow connection, or the user has impaired vision and is therefore using a text-based reading machine to browse by listening). The ALT attribute also allows text-based indexing robots to record information about images in your document.
There is an excellent discussion of the ALT attribute for the IMG tag in an article at HTML help by the Web Design Group.
The ALT attribute (or "tag") goes into the <IMG> tag as follows: <IMG SRC="source of image" ALT="some text" >.
Let's take care of the Rutgers Info Header image on your very basic homepage. Please provide an alt attribute, such as alt="Rutgers Info Header", inside the image tag that you used for your sample web-page last time. Then try out the W3C HTML validator (enter the URL of your sample Web page on the form that comes up).
For images that are purely decorative, there is no reason to
provide text, but the ALT image tag would still
be needed. In this case, use the attribute ALT=""
for that image.
Perhaps the best advice on using the ALT attribute is to think about trying to read the page to somebody who is unable to see it. You surely would skip some of the less important images, but if an image played an important role on the page, you would want to describe its function (what sort of information is conveyed, how it is related to other material on the page) and, perhaps, to indicate something more specific, so that the listener would grasp the idea conveyed by the image.
You can read in Musciano and Kennedy about the uses of the align attribute, which can be used to place the image on the screen and to control the flow of text around it. If you want to center the image, you can do it by putting the image in a centered paragraph by adding the attribute center to the <p align=center> </p> or in the (obsolescent) container <center> </center>.
In general, a URL has the form
protocol://machine-name/path. The path should end
with a slash / if it is a directory, but it should not end with a
slash if it is an ordinary file. Here are some examples:
You can form hyperlinks to files that are in your own directories by using either an absolute or a relative URL.
One useful link for those of us who would like to use our clam bookmark files while browsing the Web from the SGI machines in Fine Arts 240 would be a link to a copy of our bookmark file. Here are the steps you could take to set up a link on your sample Web page to a copy of your bookmark file.
You should now have a link to a copy of your bookmarks. Of course, if you prefer, you can do without the link in your sample Web page because you can use your clam bookmarks from any machine anywhere by entering the URL:http://clam.rutgers.edu/~your-user-id/bookmarks.html.
This sort of link to your bookmark file does have a downside: when you save some bookmarks they will not appear in your file html/bookmarks.html. That means that you would have to copy your modified bookmarks file .netscape/bookmarks.html to your public directory html/. You might ask whether there is any way of providing a link directly to your bookmarks file, .netscape/bookmarks. We will return to this topic in class 10 and will look at a better way of linking to your bookmarks file.
There is a useful simile, perhaps a cliché: getting information from the Internet is like getting a drink of water from a fire hose. There is plenty of information, but how do you find what you are looking for without drowning in it?
If you have a general idea of what you are looking for, then a good place to start is with an electronic, on-line, index. For example, if you are looking for information about Rutgers, then you might start with the Rutgers home page. Suppose, for instance, that you want to find out about the possibility that there is a club that interests you. For example, suppose you want to know whether there is a ski club somewhere at Rutgers University. You could go to the "Search at Rutgers" hyperlink, and try to find on-campus sites that contain the string ski. That returns too much irrelevant material. Try it! However, you could use the "Advanced Search" option to look for documents that contain only the word "ski" or the word "skiing" by using a construction something like this: "ski" or "skiing". Try it this way now!
Suppose you are looking for information about a specific mathematical topic, wavelets, for example. You could start with the subject index at Yahoo, click on Science, click on Mathematics, and there you will find an entry for Wavelets. Or you could start at the WWW Virtual Library, click on Mathematics, click on Specialized Fields, and click on Wavelets. Try it!
Suppose you would like to know about studying mathematics at the Universität Mannheim. You could go to the list of Mathematics Information Servers at the Penn State Department of Mathematics, click on Mathematics Department Web servers, scroll down the list to Germany, and select Universität Mannheim. Try it!
If you find some useful lists or useful Web pages, you can record them for future reference by using your browser's hotlist feature. In Netscape, there is a Bookmarks entry on the menu bar.
In Netscape, the Net Directory button will take you to the subject indices at Yahoo.
Keep in mind that newsgroup FAQs (frequently asked questions) can be good starting points for researching a topic. For example, see the newsgroups sci.math, sci.math.symbolic, and sci.math.research. There are also several newsgroups devoted to education.
Another way to find information is to do an automated search. This is useful if you have a topic in mind, but you have no idea where the associated resources might be located. For example, suppose you want to find information about the mathematical theory of chaos. You could go to InfoSeek and type in the word "chaos". You will get back some irrelevant references, but there will also be some hits that are of interest. Follow the links and see what turns up! Or you could try the Lycos catalog and type in "chaos" there.
If you find some useful lists or useful Web pages, you can record them for future reference by using your browser's hotlist or bookmark feature.
Here are some links to Internet subject indices.
If you don't have an idea where to find information, you can search on all the words in the text of Web pages. Suppose, for example, that you want to know more about the mathematical theory of chaos. You could go to Infoseek and type in the word "chaos". You will get back lots of links, many of no interest, but you should see some links that look promising. Follow the promising links and see what turns up!
Here are some other search engines to try:
Sometimes you may know that a program exists out there on the
Internet, but you do not know where. (For example, you need to
uncompress a .zip file on your home PC, and you know
there is unzip.exe out there somewhere, but where?)
In such cases, archie is a useful tool. Here is a
link to an article,
Meet
Archie.
Some systems (e.g., the RU-Camden servers
crab,clam and carp) have an
archie client installed as a program that you can call from the
command prompt. You just type in archie
unzip.exe, and after a little wait you should get back a list
of anonymous ftp sites from which you can download that file.
Alas, today when I tried the shell (or terminal
command archie unzip.exe it failed. When something
like this happens on a UNIX machine, you first try the shell
command man archie, but in this case, the "man
page " was not so useful. So, it seems that archie
is now outdated. It seems easier to use a web browser to search
via Google or Yahoo! at this time, but those of us who regularly
use the Mac OS X version of Sherlock know that there is a place
on the internet for search mechanisms that avoid the browser.
Although archie seems outdated, you can visit the
following site for information:
GUIDE TO NETWORK RESOURCE TOOLS.
This just in from a familiar source:
" Kid, in the good ole days, before Google, before Alta Vista, before Tim Berners-Lee launched the World Wide Web, we usedarchieto find out where software was hidden. MOreover, in those days, we had to walk 10 miles to school, uphill both ways. Life was tough."
--Crotchety Old Professor
Now you are ready to start on an Internet scavenger hunt. You are going to complete the hunt as part of this week's homework.
If you have done all the above activities, and there is still time left, here are some other activities you can do.
You should have time to start on the Internet scavenger hunt during class.
