Information and Resources

Finding Resources


There are several tools
available to help you find information at various sites on the Internet. Two of the most commonly-used browsing tools are Gopher and World-Wide Web (and its clients, such as NCSA Mosaic or Lynx).

Gopher

Gopher is a user-friendly interface developed at the University of Minnesota; it allows you to browse through files before retrieving them and allows you to search WAIS indexes. You can use Gopher to access STEIS by typing the following command (Figure 9.3 shows the results):

gopher ftp.stsci.edu 
In addition to Gopher, there are three related tools to help you find files and programs on the net:

We will describe Archie in more detail in the next section, but will leave the exploration of Veronica to you.



Figure 9.3: Using Gopher to Access STEIS

Archie

If you want to find out where to get a particular piece of software or other information,
use Archie. Archie was developed at McGill University as a data base of network resources, and tracks the contents of over 800 anonymous ftp sites.

To use Archie, you can either set up an Archie client or you can use telnet to access an Archie server. See the sample Archie connection in Figure 9.4. Use the username "archie" when you connect, you will not be asked for a password. You can get help after connecting to the remote Archie server by typing help.



Figure 9.4: Connecting to Archie

World-Wide Web

The World-Wide Web (sometimes referred to as WWW or W3) is a hypertext-oriented way of navigating through the Internet and finding information. The WWW project was started and is maintained by CERN (the European Laboratory for Particle Physics). Hypertext is text that contains links to other documents. Access to WWW is handled by running client software (a browser) on your local host.

Two clients are available for VMS users: NCSA Mosaic and Lynx. NCSA Mosaic runs under the X environment, so only users with workstations can use the Mosaic client. All other users can use the terminal client, called Lynx. Either browser allows you to read hypertext documents that are made available at individual internet sites (such as STEIS) and to navigate from document to document by following links, which fetch selected hypertext documents. The location of each document is described by an address called (in WWW jargon) the uniform resource locator (URL). The home page for STEIS is fetched by the following URL:

http://www.stsci.edu/top.html
Highlighted text is connected--or linked--to other documents, images, or files. To navigate in hyperspace use your browser to select the highlighted topics of interest. Selection is done differently by different browsers. In Mosaic, you select buttons (boxed commands) or highlighted text by using the left mouse button. In Lynx, you simply move forward and backward between links using the up and down arrow keys ( and ), and then press the right arrow key ( ) to follow the link. Figure 9.5 shows a sample of the X-based NCSA Mosaic interface. For more information about using Mosaic, select topics from the "Help" menu at the top left corner of the window. Figure 9.6 shows the Lynx interface. To start Lynx, simply type the word lynx at the system prompt. For information about using Lynx, type .



Figure 9.5: Using Mosaic to Read WWW Home Pages

You can also create your own home pages and then start Mosaic with your own set of links. To do this, you need to learn about HTML and create an HTML source file. You then start Mosaic by typing the file name of your home page on the command line when you start Mosaic, for example:

$ mosaic myhomepage.html


Figure 9.6: Using Lynx to Read WWW Home Pages

Gopher
Figure 9.3: - Using Gopher to Access STEIS
Archie
Figure 9.4: - Connecting to Archie
World-Wide Web
Figure 9.5: - Using Mosaic to Read WWW Home Pages
Figure 9.6: - Using Lynx to Read WWW Home Pages

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