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An NExS spreadsheet has the ability to connect to
external programs called NExS connection clients. NExS
connection clients can:
- exchange data with NExS.
- establish new menus on the NExS spreadsheet.
- create and install new functions which are entered and
recalculated just as if they were NExS built-in
functions, like @SUM.
- perform control functions, such as recalculating the
spreadsheet, evaluating cell constraints, or moving
the cursor to a different cell.
Connection clients may be programs running on the same
workstation as NExS itself, or they may be programs
anywhere in the computer network. For example, you might
have a connection client running on a supercomputer on
the network which extracts a block of data from the
spreadsheet, performs a compute intensive simulation, and
returns the results to the spreadsheet where they may be
viewed, printed, graphed, or further analyzed.
There are four basic ways in which an NExS connection
client can extend and enhance the NExS spreadsheet:
- Real-time data exchange with processes running on your
computer network. NExS connection clients can store
data (numbers, text, and formulas) in the spreadsheet
and retrieve data from the spreadsheet in real-time.
(Here, real-time is loosely defined to mean "as it
happens, excluding any network and operating system
delays.") The NExS spreadsheet may by used normally
for any operation such as manually entering or
editing data, reformatting cells, printing reports,
plotting graphs, etc., while the real-time data
exchange occur.
- Extending NExS's built-in functions and embedded tools
with user-defined functions (written in C or FORTRAN).
Extrinsic functions installed by a connection client
appear to the user to be identical in form and
behavior to NExS built-in functions.
Unlike NExS built-in functions, however, the user
defined extrinsic functions are not necessarily
executed by the local workstation; they are executed
by the connection client program which installed them
from anywhere in the network. As such, they can
perform very powerful or very specialized operations,
like "number crunch" computations on a supercomputer,
remote data base queries, or extraction of parameters
from a CAD tool running in another window on your
local workstation.
- Extending NExS's menu-based capabilities by adding new
menus and buttons to the Motif menu bar at the top of
the spreadsheet. NExS connection clients may create
one or more new pull-down menus on the NExS
spreadsheet, each of which may have one or more
buttons which when activated by the user, invoke a
function to be performed by the client program. To
the user, these new menus appear simply as extensions
to NExS's built-in tools and utilities.
- Remote control of NExS. A connection client may be
programmed to take control of NExS, entering data,
performing recalculations, loading and storing
spreadsheets, and moving about in the spreadsheet
window. It is also possible for a connection client
to lock out user input to NExS, so that the client is
in complete control. This feature could be useful in
a real-time data monitoring application, where the
user is allowed to view the incoming data, but not to
modify or manipulate it.
Consider the potential for using connections in your work
- having NExS accept, process, display, and transfer
information to and from other programs in real-time, that
is, as it happens, being continually updated on screen as
you watch. For example, you could:
- create a spreadsheet that organizes and displays
process-control data in a format of your design, then
pass that data to other programs for other purposes.
- monitor quality-control data fed continuously from a
manufacturing process - or scientific data from a
laboratory instrument - in any format you define.
- create your own built-in functions and call them from
an NExS spreadsheet.
- pass extremely demanding calculations to a
supercomputer that can calculate many times faster
than your workstation, then pass the results back to
the spreadsheet on your workstation.
- conduct continuous statistical analyses of an
ever-changing population sample.
- use NExS to custom-design a form to display stock
prices.
- use NExS as the front-end for any custom-written
program, thereby saving yourself the programming
effort required to create user interfaces.
Next: 10.3.1 How Connections Work
Up: 10 Interacting with Other
Previous: 10.2.6 Exporting Data as
NExS User's Guide, Version 1.4.5
Grey Trout Software
11 April 1999