JODA

1
JODA

• A Testbeam Online Display and
• Analysis Program in Java
• Dietrich Liko Niko Neufeld

2
What is Joda

• Online Monitoring of HPD data
• Visualization of the photosensor
• Various histograms
• Charge, Multiplicity, Noise
• Interface to PAW for more detailed analysis
• Fitting, Extration of derived quantities
  (efficiencies etc.)

3
The task

• Replace existing Fortran, Tcl, C program for the
  Pad-HPD testbeam by an integrated Java program
• Learn as much as possible about Java
• Write a clean, Object Oriented solution to the
  problem

4
Why Java?

• Java is a viable alternative to C (or is it?)
• Java has easy interfaces to the Web, graphics,
  CORBA, etc.
• Java is more easy to handle and more OO in some
  respects
• Java comes with a huge and powerful multipurpose
  Class Library, the JFC

5
Program features

• Display in AWT using custom light-weight
  components
• Read in of raw data files in compressed or
  uncompressed format, with flexible byte ordering
• Flexible display of various detector related
  quantities, auto updating while following the
  mouse

6
Program features (contd.)

• Uses multi-threading (easy and effective in Java)
• Uses customized Listener, Multi-caster
  design-pattern for asynchronous communication
  (copy, adapt and extend Design Patterns from the
  book, or Java itself)

7
DesignpatternModel View Controller (MVC)

• Well know pattern in GUI building
• Widely used in SWING
• Easy to understand

From Design Patterns Gamma et al.
8
Prototype

• One Detector only
• No Histograms
• No printing
• Java 1.1.2
• Runs also as an applet in your browser

9
A screen shot
Try it http//nikolaus/joda
10
Features (to be) added for the new Version

• Support display of many HPDs and Beam-Telescope
  planes
• JNI (Java Native Interface) to HBOOK (ready)
• Support access to Objectivity/DB (Mario Alemis
  Boss)

• Enable printing of detectors and screen shots
• Use Java native serialization for easy and rapid
  storage

11
Joda - the next step

• Java is rapidly evolving - Sun is releasing JDK
  1.2.3 very soon
• Better GUIS and graphics with Java 2D and SWING
• Java 2D advanced 2D drawing concepts (different
  stroke widths and textures)
• SWING
• modern GUI components like scrollbars, desktops,
  icons, etc.
• Performance improvements double buffering

12
Joda goes Swing
13
Programming experiences ?

• Slower (not a problem in this application)
• Platform independence (somewhat) spoilt by
  different Java Virtual Machines and restrictions
  for Applets
• AWT event handling and scheduling (for example of
  screen-repaints) can be somewhat cryptic

14
Programming experiences ?

• Java is an excellent powerful programming
  environment
• Object orientation goes in much smoother than in
  C
• Learning curve is steeper and debugging phase
  much less painful than in C (clear error
  messages!)
• Platform independent (no more porting from Linux
  to HP to Windows to )

15
Some thoughts

• We should keep an eye on Java
• Maybe we should do some field tests to see if
  and where Java is suitable for physicists tasks
• Find out if average users feel more comfortable
  with it than C
• A mixed C/Java environment should be no problem
  (easier than C/Fortran was)

16
The last slide -An invitation

• Although this is work in progress...
• try the display on your web-browser at
  http//home.cern.ch/nikolaus/joda
• if you like it, come back when the SWING version
  goes WWW