As he was leaving for a meeting in Asheville, John remembered reading
somewhere that the North Carolina Department of Transportation had
announced plans to rebuild and extend parts of I-26. John barely had
enough time as it was; if much of that stretch of road was currently
under construction, he would need to call and say he would be late.
Going to his desktop computer, John used NCSA Mosaic, a new Internet
interface, to find the North Carolina Department of Transportation
highway construction projects map and was happy to see that the plans
affected only one short section of the highway south of Asheville. John
selected "I-26 improvements south of Asheville" and read the project
plan. Aside from the work on one bridge, all the lane closings would be
at night; he should still be on time.
The past several months have seen unprecedented coverage of the Internet
in the popular press. Until now, though, navigating the network has been
an exercise in frustration for even the most ambitious networker. Now a
new software program promises to make Internet access easy and
transparent for the everyday user.
NCSA Mosaic, developed by the Software Development Group at the National
Center for Supercomputing Applications, is a window on the ever-
expanding world of on-line information. As a distributed hypermedia
browser designed for information discovery and retrieval, NCSA Mosaic
provides a unified interface to the diverse protocols, data formats, and
information archives used on the Internet.
With NCSA Mosaic's hypermedia-based interface, electronic links known as
hyperlinks are embedded in richly formatted documents that can include
full-color images and sounds. NCSA Mosaic presents these documents like
the pages of an interactive, scrollable, online book. You can move
around within complex documents, as well as from document to document
across the network, simply by clicking on these hyperlinks. You use the
same interface for navigation and for document viewing; you can even
retrieve information from Gopher, WAIS, and anonymous FTP servers
without moving to a different application for each one.
NCSA Mosaic and the WorldWide Web
The Internet has grown up during the past two decades as a loosely
federated worldwide collection of information resources and services.
NCSA Mosaic itself is part of the WorldWide Web environment, a system
for maintaining distributed hypertext that originated at the European
Laboratory for Particle Physics, CERN, in Geneva, Switzerland. Initially
developed to keep track of researchers' information and to provide an
easy method of sharing information among scientists, the Web has grown
into one of the world's most widely used tools for information
publishing, discovery, and retrieval.
The Web employs several established or developing standards to make it
as universally usable and reliable as possible. It uses a standard
naming convention--known as the Uniform Resource Locator, or URL--to
locate individual pieces of information sitting on machines anywhere
across the network. Clients and servers use a standard transfer
protocol--known as the HyperText Transfer Protocol, or HTTP--to send and
retrieve documents across the Web. Documents on Web servers are
formatted with a standard markup language known as the HyperText Markup
Language or HTML. The HTML specification includes the hyperlink format
that allows users to move around the Internet by jumping from one
document to another.
Building on the Web's initial structures, NCSA Mosaic uses a
client/server model for information distribution. A server sits on a
machine at an Internet site answering queries sent by NCSA Mosaic
clients, which may be located anywhere on the Internet. To users, the
client looks like any other application on their machine, only this one
has immediate access to information all over the world. The pieces of
information sent from servers to clients are known simply as documents,
which may contain plain text, formatted text, graphics, sound, and other
multimedia data.
An Integrated System
The NCSA Mosaic system is an integrated set of browsers, viewers,
servers, gateways, and filters that allow you to approach the Internet
as one consistent information source. At the simplest level, the NCSA
Mosaic clients provide navigation and document viewing capabilities for
browsing the information universe of the Internet. As your interest,
needs, and skills develop, the configurable addition of external viewers
allows easy and straight-forward expansion to handle virtually any
specific type of data. This flexibility will allow you and NCSA Mosaic
to keep pace with the quickly evolving world of multimedia and allows
NCSA Mosaic to be custom configured for any working environment.
The NCSA Mosaic system is a completely open framework; you can enter at
your most comfortable level, progress through the use of various
viewers, learn to create your own hypertext documents, set up your own
server, engage in multimedia collaboration with colleagues in distant
locales, develop scripts for specialized information filtering and
presentation, and develop gateways to unqiue information resources and
integrate them into the NCSA Mosaic information space for other users.
In short, the possibilities are endless; you can think of NCSA Mosaic
and the Web as allowing the progressive customization of your own
information space, and that of your group.
External Viewers
There are myriad types of data available on the Internet, many of which
must be stored, read, and interpreted in a unique manner. Though NCSA
Mosaic is not designed to read and interact directly with all of them,
the system relies on external viewers in order to work with the widest
possible variety of image, audio, video, and typeset data formats. These
external viewers are separate programs that are invoked when necessary
to display certain types of data.
With the external viewers, users are not limited by the NCSA Mosaic
(anyone can use any viewer that will work with NCSA Mosaic to view any
type of data). Plus, as new viewers and data types appear, they can be
easily integrated into the NCSA Mosaic environment without rewriting the
application software. For example, the various NCSA Mosaic clients can
use the following external viewers:
lviewfor the Microsoft Windows client
A Windows utility that plays GIF, JPEG, and TIFF images as well as
images recorded in several other formats.
Ulawfor the Macintosh client
A Macintosh utility that plays audio data.
xvfor the X Window System client
An utility that displays GIF, JPEG, and TIFF images as well as images
recorded in several other formats.
These are just a sample of the available viewers. NCSA makes
several standard viewers available, but the system can be configured to
accommodate other viewers.
Setting Up the Client
NCSA Mosaic is implemented for three types of platforms:
X Window System
Macintosh
Microsoft Windows
Each implementation takes advantage of the strengths of its respective
platform, but they have all been implemented to preserve as much cross-
system compatibility as possible. All three clients can be downloaded
for personal use from NCSA's anonymous FTP server. (See Downloading
Clients from the NCSA FTP Server.)
Installing and running an NCSA Mosaic binary is straightforward. The
procedures differ slightly across the X, Macintosh, and MS Windows
platforms, but they are installed like any other application on their
respective platforms. The installation procedures are fully described in
the readme files referred to in "Downloading Clients from the NCSA FTP
Server" and in documentation that can be found once the files have been
downloaded and uncompressed.
To use NCSA Mosaic as an Internet browser, the system on which it is
installed must be fully connected to the Internet. This is because the
first thing NCSA Mosaic usually does when you run it is download one of
the NCSA Mosaic Home Pages (the startup document) from an NCSA server.
If NCSA Mosaic executes but you get an error message instead of a home
page, the problem is most likely in your Internet connection; you will
have to get that connection established before you can use NCSA Mosaic
to navigate the Internet. NCSA Mosaic can also be used as a
collaborative tool within a working group without an Internet
connection, but such applications are beyond the scope of this article.
Where Can I Go from Here?
Once you have successfully installed NCSA Mosaic, you should spend some
time becoming familiar with the interface. The NCSA Mosaic Demo
Document, available via a hyperlink in the NCSA Mosaic Home Page or via
a menu selection, provides an overview of NCSA Mosaic's capabilities
with hyperlinks to a wide variety of information sources. As you browse
the information universe, you can access material through other menu
selections and other home pages.
Serving Information
To distribute information via the World Wide Web, you will want to set
up an HTTP server. The HTTP protocol is stateless, lightweight, and
extremely fast, but provides capabilities not found in earlier
protocols, such as FTP. HTTP servers are currently available from varous
Web sources for UNIX, Macintosh, and Microsoft Windows systems.
If you wish to publish hypertext documents, you should first learn about
HTML--the formatting standard for hypermedia documents in the Web
environment--and URLs--the scheme for consistently naming documents
accessible on the Web. You will find hyperlinks to HTML and URL primers
at the very end of the NCSA Mosaic Demo Document mentioned earlier.
Those primers in turn point to more advanced information sources.
Current Release Levels
In November and December 1993, NCSA released the following versions of
NCSA Mosaic:
NCSA Mosaic for the X Window System
Version 2.0
This version can be used on almost any modern UNIX-based graphics
workstation (e.g., Sun Sparc, IBM RS/6000, DEC 5000 or Alpha, Silicon
Graphics IRIS).
NCSA Mosaic for the Macintosh
Version 1.0.2
This version can be run on any Macintosh, including SEs and Classics,
running System 7.0 or higher.
NCSA Mosaic for Microsoft Windows
Version 1.0
This version can be used on any Intel 80386SX-based PC (or better)
running Microsoft Windows release 3.1 or later. This client will run
with 4Mb, but NCSA recommends a minimum of 8 MB of RAM.
NCSA Mosaic is being continually developed. The most up-to-date versions
can be accessed by checking NCSA's FTP server.
E-mail queries concerning these releases can be sent to the following
addresses:
Macintosh
[email protected]
Windows
[email protected]
Downloading Clients from the NCSA FTP Server
NCSA Mosaic can be acquired from NCSA's anonymous FTP server. You must
first execute the following FTP command:
ftp ftp.ncsa.uiuc.edu
Enter anonymous at the login prompt and press Return. Enter your e-
mail address (e.g., jdoe@business. com) at the password prompt.
If you have never downloaded files from this server, download and
read the file README.FIRST.
You will find NCSA Mosaic executables in the following directories.
Initial installation instructions can be found by reading the indicated
readme file for each client:
Macintosh executable:
/Mosaic/Mac/
Macintosh readme:
/Mosaic/Mac/NCSAMosaic.1.0.2.README
Windows executable:
/Mosaic/Windows/
Windows readme:
/Mosaic/Windows/readme.now
X executable:
/Mosaic/Mosaic-binaries/
X readme:
/Mosaic/README.Mosaic
Please note that these clients are copyrighted but free for
noncommercial use; NCSA and the University of Illinois retain the
copyright but will allow anyone retrieving the software from the FTP
server to use it personally without any further license. Anyone who
wishes to use or distribute the software commercially must first obtain
a license. The full NCSA Mosaic copyright notice can be viewed online
with any NCSA Mosaic client.
Setting Up a Server
NCSA has developed a freely available HTTP server for UNIX platforms. It
is available from NCSA's FTP server in the directory
/Mosaic/ncsa_httpd
Full configuration instructions are provided with each of the binary and
source distributions available there. Send e-mail to the following
address if you have any questions or problems:
[email protected]
For More Information
The best way to get more information on NCSA Mosaic, the WorldWide Web,
the Internet, and related technologies is to get online and start
browsing. The online information is extensive and constantly updated.
If you are looking for information on the Internet, The Whole Internet
User's Guide and Catalog, by Ed Krol of the University of Illinois, is
an excellent source. This book is published by O'Reilly and Associates.
Frank Baker ([email protected]) is a technical writer with the NCSA
Software Development Group. NCSA, the National Center for Supercomputing
Applications, is located on the campus of the University of Illinois at
Urbana-Champaign and is funded in part by the National Science
Foundation. Several members of the NCSA Mosaic development team
contributed to this article.