This non-signed Java Applet (The Java Run-time Environment
[JRE] has to be installed on your computer
for running this applet.) consisting of 17 classes (total size = 66 kB) (or
merged into a single jar file [size = 45 kB] for Java 1.1.x capable browsers)
and 3 gif files (total size = 70 kB) allows you to inspect
on-line the current official status of the PSI Proton Accelerator Facility. The update
rate of the changing data is 1 Hz at the maximum. Because different parts of the
applet are running in separate single instance windows the browser's window may
be minimized once the applet is started. The applet's main window shows the date
and time, the outside temperature, the total used electrical power, the 6
proton beam currents and the operator's messages all transmitted periodically
via multicast UDP/IP by the ACS (Accelerator Control System). A program running on an own
WWW server (PC9687, OS = Linux) collects
these data and writes them into files located in the applet's own "sandbox" from
where they are fetched by the applet's running instances via http (Apache server is
installed on pc9687).
Five push buttons in the applet's main window allow you to view the gathered data in separate windows in a more detailed form:
|History||The last 1, 12 or 72 hours of the 6 different proton beam currents, the outside temperature and the total electrical power may be seen as a histogram. Refreshing is done automatically with a reasonable frequency.|
A Gif bitmap of the PSI experimental hall is shown with the actual proton beam currents in blue
flashing rectangles and the used targets and running accelerators marked with red flashing dots.
When clicking with the left mouse button on one of the 7 secondary beam line regions, a
list box containing the actual device settings (names, DAC- and ADC-values) pops up.
The list may remain empty, if you browse the Web via a proxy-server.|
If a device name in this list box is clicked at with the mouse, then a dialog box is popping up through which authorized persons may change the setting of the selected device. The applied password policy is not disclosed here.
|Analog||The 6 proton beam currents in µA are shown in a bar chart. The length of each bar is updated once per second. When clicking with the mouse pointer at one of the bars, then a "moving coil meter" with the corresponding current being displayed is popping up. Finally, when clicking at the left/right side of the gray part of the meter, then the previous/next in the list of the 6 beam currents is displayed.|
|Messages||The collected operator's messages over the last few days are displayed. The text window content is limited to ~7 kB and organized as a FIFO. The Refresh button reloads the (updated) text from the server.|
|HE info||Some statistical data which describe the quality of the 590 MeV proton beam over the last 24 hours are shown. The Refresh button reloads the (updated every 120 sec) table from the server.|
This Java Applet allows you also to inspect on-line the current settings of
the 7 Secondary Beam Lines of the PSI Proton Accelerator Facility. Updating of the
data is done about every 20 secs by a multi-threaded round robin procedure
(programmed in C and running on PC9687) collecting the data from the 7 area
servers via TCP/IP and making them available for this applet via http connections.
The applet allows authorized persons also to modify all DAC settings of the 7 secondary beam lines. This new feature has been implemented with the help of an own Java-CGI interface.
Be also aware of the fact that when this applet is running it maintains network connections (directly or indirectly) to as many as 10 computers (see Fig.1: 9 kB).
If you are only interested in the Secondary Beam Line Settings and you have a 16-bit browser with no Java VM support, then you may use a Java Script Applet instead.
This applet has been seen working on the following platforms (OSes) with browsers:
If you are using a browser with at least Java 1.1.x capabilities (like Netscape's Navigator 4.5 and higher, Sun's Hotjava 1.1 or Microsoft's Internet Explorer 4.0x and higher for Windows platforms), then it will automatically choose the newer version of this applet, which is based on the Java 1.1 API (more reliable) and down-loadable as a single Java archive (faster).
In order to improve the platform independence, the push buttons of the top and the history frame are user-drawn (and colored).
Last updated by Urs Rohrer on 14-Feb-2006