BaBar Fast Monitoring

1
JAS in BaBar Online Monitoring 
V. V. Serbo, for the BaBar computing group
Stanford Linear Accelerator Center,
Stanford, CA 94309, USA.
Abstract In order to insure the quality of
collected data, hundreds of monitoring histograms
are filled during the BaBar run. Babar is using
JAS (Java Analysis Studio, http//jas.freehep.org
) as a means of presenting online monitoring
histograms to people on shift. JAS is an
interactive analysis application, written in
Java, with a rich GUI and ability to work in
client/server mode as well as a stand-alone
application. Three-tier approach is used, with an
intermediate server that acts as a gateway
between BaBar CORBA-based distributed histogram
facility and JAS RMI-based client/server
communication protocol. The server is implemented
in Java and uses the JAS online monitoring API.
Histograms are displayed in the JAS client using
HTML pages with embedded live and reference plots
for each detector subsystem. The HTML pages also
provide descriptions of the plots, instructions
and contain hyperlinks to additional pages with
more detailed diagnostic histograms.

• Written entirely in Java really portable.
• Originally targeted at offline analysis, but also
  used extensively for online monitoring.
• Rich, easy to use GUI.
• Can view trees, plots, HTML pages
• with embedded active objects.
• Built-in editor/compiler.
• Local and Client-Server Operation.
• Can send analysis code to the data
• and ship back only the results.
• JAS info, demos, downloads
• http//jas.freehep.org

• BaBar Online Monitoring
• During the run hundreds of monitoring histograms
  are filled using part of BaBar data.
• Live histograms are accessible through the BaBar
  DHP CORBA Server.
• DHP Distributed Histogramming Package in BaBar
  framework.
• Jas Interface Server
• - Connect C and Java world
• - Concentrator for JAS clients
• - Cashing of data
• BaBar runs several DHP servers that provide live
  and reference histograms.
• Two Jas Interface Servers one for people on
  shift and one for everybody else.

• Features of JAS Plots
• Plots update in real time.
• Data for plots can be local or remote (use Java
  RMI to connect to JAS Data Server).
• Rich variety of styles for 1D and 2D plots.
• Integrated with simple fitting capability.
• High quality print output and export of plots in
  a variety of formats, including PS, EPS, PDF,
  SVG, GIF, PNG.
• Live plots can be embedded in the HTML pages.
• Overlays data from several independent sources
  can be displayed in one plot.

• Monitoring BaBar data quality
• During the run HTML pages with
• Live plots
• Reference plots
• Instructions for people on shift.
• Archives Monitoring Histograms are archived at
  the end of each run.

• Future
• JAS3 (http//jas.freehep.org/jas3) uses a highly
  modular component based framework, into which
  various analysis modules can be plugged.
• Can be customized for a particular problem domain
  by addition, replacement or removal of modules.
• Relies on Java FreeHEP Library (http//java.freehe
  p.org).
• Scripting support (Jython, pnuts).
• Some of the existing modules WIRED
  (http//wired.freehep.org), JAS Plotter, JAIDA
  Java implementation of AIDA (http//aida.freehep.o
  rg).

• BaBar Monitoring applications will become JAS3
  pluggable modules.
• More features, less code, shorter development
  cycle rely on functionality of other JAS3
  modules.
• URL-like protocols to access remote data
• Full description of data location
• Alias location relative to the server name
• Can use same access mechanism for interactive
  access and in HTML pages.