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Shukla, H., Scott, S., & Weaver, S. 1999, in ASP Conf. Ser., Vol. 172, Astronomical Data Analysis Software and Systems VIII, eds. D. M. Mehringer, R. L. Plante, & D. A. Roberts (San Francisco: ASP), 95
Remote Observing With Java
Hemant Shukla, Stephen Scott
Owens Valley Radio Observatory, PO Box 968, Big Pine, CA 93513
Simon Weaver
Principia College, Elsah, IL 62028
Abstract:
We demonstrate the next generation of monitor and control software for
Caltech's Millimeter Array at the Owens Valley Radio Observatory. The
software is based on a client/server architecture and provides remote
access for controlling, monitoring and troubleshooting the array. The
client is written in Java and thus provides a Web based interface that
is supported on many machine architectures and operating systems. The
server software is developed in C++ and runs on a UNIX host machine.
Data from the microcomputers embedded in the array are transported to
the UNIX host shared memory area where they are then available to the
server programs. Security algorithms are implemented to authenticate
remote access for control of the array. The design of the software
makes it portable to other observatories with little modification.
This computer demonstration consists of remote observing with the
Caltech Millimeter Array located at Owens Valley in California to show
the feasibility and features of this software package. The demo with
realtime status of the array is available on the
web.
Many of the details of the implementation have been presented in the
paper submitted in ADASS VII (Scott & Finch 1998) and this is
complementary to that paper. However, in the last year there have
been various additions to the program that are further discussed.
Any remote access request to control the array has to be authenticated
at the server end. The authentication is made against the UNIX
username/password pair in the OVRO server, thereby requiring the user
to have a UNIX account on the server beforehand. To avoid password
sniffing over the net, the username/password pair is encrypted. Only
the monitoring of the array (browsing) is allowed for the
non-authenticated users. The modular nature of the authentication
function makes it easier to implement other restriction/permission
rules based upon machine address or domain name if desired.
The flexibility of the basic realtime window has been increased by
adding a pulldown menu that allows other windows to be launched
separately or overlay the existing window. Space has been conserved
by eliminating the buttons controlling plotting and printing and
migrating the functionality to pulldown menus.
Figure 1:
The Login window required for remote authentication
(left). Unauthorized users may click on the Guest button and
provide courtesy user name for only monitoring mode. Menu window
(right).
![\begin{figure}
\par\plottwo{shuklah1_a.eps}{shuklah1_b.eps}
\end{figure}](img1.gif) |
Figure 2:
Array Status window.
![\begin{figure}
\plotone{shuklah2.eps}
\end{figure}](img2.gif) |
The package has proved to be very portable if realtime data is
available in shared memory. The observatory specific features have
been segregated to allow for easy customization.
Figures 1 through 3 show some sample
windows running on a UNIX based machine.
Figure 3:
Clockwise from upper left -- receiver window, control widget for
changing the values, list of the cell values, and the plot of the
values.
![\begin{figure}
\plotone{shuklah3.eps}
\end{figure}](img3.gif) |
References
Scott, S. & Finch, R. 1998, in ASP Conf. Ser., Vol. 145, Astronomical Data Analysis
Software and Systems VII, ed. R. Albrecht, R. N. Hook, &
H. A. Bushouse
(San Francisco: ASP), 49
© Copyright 1999 Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, California 94112, USA
Next: Real-Time Linux Driving a Spectrometer
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