3 Web Navigation
Several options are built in to NCSA Mosaic to help you move
among documents. These include hyperlinks, the Forward and
Backward buttons, as well as History and Hotlist on the Navigate
menu.
Moving Around
Think of the documents you have viewed using NCSA Mosaic
as being a stack of papers on your desk. Instead of looking
through the papers, you are viewing them in an NCSA Mosaic
window. Document1 is at the bottom, with document5 on top
of that, then document7, and document14 on the very top.
You are viewing document14.
Figure 3.1 A Stack of Documents
You have two ways to move forward (the hyperlink and the
Forward button) and two ways to move back to one of the ear-
lier documents (the Back button and Window History).
Using Hyperlinks
An underlying philosophy of the Web is that documents pro-
vide you with hyperlinks to other related information. These
hyperlinks provide the web elements that give the Web its
name. You can follow the same hyperlink an infinite number
of times.
A hyperlink (sometimes called an anchor) is a highlighted
word or graphic that, when activated (clicked on), takes you
to a new document or resource somewhere on the Internet.
The new document can be, among other things, a text file, a
graphic, an audio clip, a telnet session, or a WAIS (an indexing
and retrieval system) search. Hyperlinks are established by
the author of a document.
Hyperlinks to other documents are designated by highlighted
words or outlined graphics. NCSA Mosaic highlights one of
the following ways:
¥ color
¥ underlining
¥ both color and underlining
NOTE: The color and underlining defaults can be changed in
your .Xdefaults file. See ÒSystem Configuration and Modifi-
cation AssistanceÓ on pageÊCÐ1 for additional information.
Underlining can also be changed using Anchor Underlines on
the Options menu.
To activate a hyperlink, single click with the left mouse but-
ton on the word or graphic that is highlighted.
Once you view a hyperlinked document, the hyperlink in the
original file changes its appearance. For example, if an
unviewed hyperlink is underlined, the underlining becomes
broken (or dashed) after viewing. If the hyperlink is displayed
in a color, the color changes after viewing. You can view
hyperlinked documents again.
All other references to the same document change to show
that you have already viewed it. For example, if you are read-
ing document1, and you activate a hyperlink to document5,
the next hyperlink to document5 (which could be in
document14) is shown as viewed (with a different color or a
change in the underlining style).
The Forward Button
One way to move forward is to single click with your left
mouse button on a hyperlink included in a document.
Remember you can follow the same hyperlink an infinite
number of times.
Generally you move to another document by following a
hyperlink. If you have retraced your steps to a previous docu-
ment (see below), you can move to the most recent document
by clicking on the Forward button in the bottom control panel
of the Document View window.
For example, using the same stack described above, if you
view document14 and moved backward to document7 using
one of the methods described in the next two sections, you
can move forward to document14 by clicking on the Forward
button.
The Forward button is dimmed (right, below) if NCSA Mosaic
has no document to move forward to.
Figure 3.2 Forward Button
If one of the documents you look at was opened by an exter-
nal viewer (such as xv), you cannot return to it without click-
ing on the hyperlink again. NCSA Mosaic does not include
documents viewed with the external programs in its tracking
of where you have been.
The Back Button
The Back button in the bottom control panel returns you to
the last document you viewed. In the sample stack shown
above, pressing the Back button returns you to document7.
Pressing it again returns you to document5.
Going Back to an Internal Hyperlink
Some documents have a set of internal hyperlinks from one
location in a document to another location in the same docu-
ment. Those hyperlinks tell NCSA Mosaic to move from one
location in the document to another in the same document.
In this case, using the Back menu option or button returns
you to the start of the hyperlink.
An example of internal hyperlinks can be found in the Begin-
nerÕs Guide to HTML on the NCSA Mosaic Help menu. The
Òtable of contentsÓ on the first screen of that document is a
set of internal hyperlinks within that guide. The Back button
returns you to the start of the hyperlink.
Window History
NCSA Mosaic keeps track of most documents you view dur-
ing your session. (It does not record the documents seen with
external viewers such as xv.) The list of documents you have
viewed is maintained in the Window History window.
Figure 3.3 Window History Window
Selecting Window History from the Navigate menu brings up the
Window History window showing Where youÕve been. This lists
the documents you have viewed in sequential order. In the
list shown above, you can easily return to the NCSA Home
Page by opening your Window History and doubleclicking on
the NCSA Home Page from the list of viewed documents. (You
can also use the middle mouse button to select the docu-
ment.) Using Window History is often the quickest way to return
to a document you viewed many hyperlinks ago.
Exploring on Your Own
One of the best features of NCSA Mosaic is how easily you
can move through the global web of information available
online. Each hyperlink moves you to yet another document
available on the Web.
The Navigate and Help menus give you three good places to
start your explorations. The documents listed below are
retrieved from the NCSA Web server:
¥ On the Navigate menu: Internet Starting Points lists interest-
ing documents on the Internet including some home
pages, services, hyperlinks to other types of servers, and
information sources of particular interest to new users.
¥ On the Navigate menu: Internet Resources Meta-Index compiles
the various resource directories and indices available on
the Web.
¥ On the Help menu: Mosaic WhatÕs New Page is the best way to
find out about new resources, interesting additions to
existing resources, as well as fun exhibits on the Internet.
This document is updated frequently, so check it often.
To learn more about NCSA MosaicÕs capabilities, check the
Demo... document available from the Help menu. It walks you
through what NCSA Mosaic can do and hyperlinks to some
outstanding examples of hypermedia on the Internet.
Global History
NCSA Mosaic not only keeps track of documents you have
viewed in the current session but also the documents you
have viewed in all your NCSA Mosaic sessions to date. This
information is stored in the .mosaic-global-history file (the
default name) in your home directory. By maintaining the his-
tory list, NCSA Mosaic knows which hyperlinks to show as
displayed (in the viewed color or with broken underliningÑ
also known as visited and unvisited hyperlinks).
Your global history file, obviously, grows with each NCSA
Mosaic session. You may want to clear the history file period-
ically to save disk space or to refresh all the hyperlinks.
Selecting Clear Global History... from the Navigate menu and con-
firming your choice clears the .mosaic-global-history file. All
hyperlinks change from viewed to unviewed.
Opening Documents Directly
On occasion you may want to open a document directly
instead of connecting to a document through a series of
hyperlinks. To do this, use the Uniform Resource Locator, or
URL for short. URLs combine the protocol, name of the
machine serving the file to the Internet, and the path and file-
name.
To open a document directly, select Open from the File menu
and enter the URL in the URL To Open field that appears in the
dialog box. Your cursor must be in the field in the dialog box
to type.
The URL Format
A URL consists of a reference to the type of server being
accessed and, essentially, the path for the specific document.
Sometimes the port number of the server is also included,
and sometimes a filename is not included because a default
file to open has been set in a directory. When you click on a
hyperlink, NCSA Mosaic interprets the URL and retrieves the
document by connecting to the Internet server that is speci-
fied in the URL. The file is then shown to you.
The required URL format is:
scheme://host.domain[:port]/path/filename
where scheme is one of the following:
Name Server Type
file your local system or an anonymous FTP (File
Transfer Protocol) server
FTP an anonymous FTP server
HTTP a World Wide Web server (HTTP stands for
hypertext transferÊprotocol)
gopher a Gopher server
news an NNTP news server
telnet opens a telnet session
WAIS a WAIS (Wide Area Information Server)
server
For example, the URL for the NCSA home page is:
http://www.ncsa.uiuc.edu/General/NCSAHome.html
where:
http is the type of server being run (a Web server)
www.ncsa.uiuc.edu is the Internet address of the NCSA Web
server
/General is the directory containing the Home Page
NCSAHome.html is the file served to you
For more information about URLs, refer to A BeginnerÕs Guide
to URLs on the NCSA Mosaic Help menu or to the original URL
information file from CERN (available as a hyperlink at the
end of the BeginnerÕs Guide).
Displaying the URL
The cursor becomes a small hand when you have it over a
hyperlink. The URL of the document under the hand pointer
is shown in the information line on the Document View win-
dow. This tells you where NCSA Mosaic will go to retrieve this
document.
Another way to see the URL for a document is to open the
document source file by choosing View Source... from the File
menu. The Document Source window displays the coded file
that is being interpreted by NCSA Mosaic (see ÒHyperText
Markup LanguageÓ on pageÊ5Ð1 for more information on the
coded file).
Using Hotlists
What is a Hotlist?
The hotlist function lets you build a list of documents on the
Web that you find useful or interesting and to which you
want to be able to move quickly. You can add or delete docu-
ments easily. Add documents to which you expect to refer
frequently, documents that refer to a specific topic, or docu-
ments that you want to tell others about.
To look at the organization of the hotlist, open the Hotlist
View window by selecting Hotlist from the Navigate menu. If
you have not added any documents to your hotlist yet, it is
empty. If you have added a document, the document title
appears in the scroll box, as shown in Figure 3.4.
Figure 3.4 Hotlist View Window
Adding Documents
To add a document to your hotlist:
1. Go to the document you want to add.
2. Select Add Current to Hotlist from the Navigate menu.
This appends the documentÕs URL to the hotlist and displays
the document title in the Hotlist window.
The other way to add a document is to:
1. Go to the document you want to add.
2. Select Hotlist from the Navigate menu.
3. Click Add Current.
Removing Documents
To remove a document from your hotlist:
1. Choose Hotlist from the Navigate menu.
2. Select the entry to be deleted.
3. Click Remove.
Editing Hotlist Information
Edit the title of any entry in the hotlist by selecting the entry
and clicking on Edit Title. The Edit Hotlist Entry Title opens.
Enter additional information or modify the default informa-
tion as you like. Click Commit to save the changes.
For example, you might want to add the authorÕs name or ini-
tials or the location of the server providing the document.
Linking to Other Documents
Move to any document in the hotlist by double-clicking on
the entry, or by selecting the entry and clicking on the Go To
button.
Sharing Your Hotlist
Use the Mail To... button at the bottom of the Hotlist View win-
dow to send your hotlist via electronic mail to a colleague.
The electronic mail is an HTML document (see ÒHyperText
Markup LanguageÓ on pageÊ5Ð1 for more information on the
mark-up language used to prepare Web documents).
Mailing your hotlist to a colleague is a way to share your
favorite or frequently used URLs. The recipient can use NCSA
Mosaic for X Window System to open the hotlist as a WWW
document by copying the electronic mail to a file, saving it
with the .html extension, and opening it as a local document
within NCSA Mosaic. Use Open Local... on the File menu. The
hotlist hyperlinks can then be used by the recipient.
Figure 3.5 shows a sample hotlist. The tags shown between
angle brackets (e.g., ,
, , etc.) are all HTML
codes. Document URLs follow the
Hotlist From E. Ogilvie, 277 English Building
- NCSA Home Page
- http://
www.ncsa.uiuc.edu/General/NCSAHome.html
- Cornell Theory Center Home Page
- http://
www.tc.cornell.edu:80/ctc.html
- Bill's Lighthouse Getaway
- http://gopher.lib.utk.edu:70/0/Other-
Internet-Resources/pictures/lights/lights.html