The
solution: Network computing: The NC model ("THIN CLIENT")
-
ANY USER can do
ANY TASK from
ANY TERMINAL.
-
Desktop tasks
(eg. file manager, text editor, calendar etc.)
-
Office tasks (eg. Word processing, spreadsheets, drawing, presentations):
-
Internet (eg. Netscape, FTP, email, news, Web design)
-
Molecular Biology:
BIRCH
-
Statistics (eg. SAS, SPSS, BMDP)
-
There is no hardware or software to
install and configure.
-
Protection from obsolescence
. It is cheaper to upgrade one server than dozens of PCs. Since the NC is
merely a display device, there is little that can become obsolete.
-
An economy of scale
. A multiuser system needs fewer megabytes of RAM and disk space,and fewer
software licenses per user than the equivalent number of PCs.
-
Greater security
is built into Unix, and enforced by professional system administrators.
-
Greater data integrity
is achieved by automatic nightly backups.
Network computing is an old idea
whose time has come again. Early computers were centrally administered, serving
numerous users via remote text-only terminals. Today, systems like Unix can
provide dozens or hundreds of users with a point and click interface comparable
to Windows or MacOS. One can think of X-windows as filling the same role as
MS-Windows, with the exception that the programs run on a server, but display
on your terminal. Terminals that can display X-windows are called X-terminals.
X terminals are one of the many possible types of Network Computers, or NCs.
When you login to your Unix account, your session runs on the central
server, but displays on your NC. Each process (window) that you
run is an independent client. It is
typically the case that a great deal of the work done by a program involves
re-drawing of client windows as you scroll, cut and paste, or open or close
windows. Under Unix, the X11 protocols are used to offload these screen drawing
tasks to the NC. This means that, when a change is supposed to be made on
the screen, the server sends an X11 command to the NC, instructing it to
do the computation necessary to, for example, move a window from one place
to another.
There are some disadvantages
to network computing:
-
Greater expertise is needed for system administration. This
problem is evaporating as each release of most Unix systems increasing automates
most system administration tasks.
-
More users needed to be cost-effective. However, as the number
of users increase, the cost per user keeps dropping.
-
Many popular PC programs are not available
for Unix. This is becomming less of a problem for three reasons:
- Migration
of applications to applications servers. Applications often run on servers,
but are controlled by the user through a local client, often running within
a web browser.
- Current MS-windows
applications can be run on some Unix platforms using
WINE (http:wine.codeweavers.com)
, an implementation of the Windows API that runs native Windows applications.
Windows does not need to be installed in the machine.
- Many
software developers are migrating to the new, write once/ run anywhere language:
JAVA (http://java.sun.com).
-
Individual loses some autonomy. There's nothing to stop the
user from buying or writing their own applications. However, installation
may require assistance from sysadmins.
For more information on some
of these issues, see the Frequently Asked Questions (FAQ)
.
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