Summary

1
Summary

• Role of Software (1 slide)
• ARCS Software Architecture (4 slides)
• SNS -- Caltech Interactions (3 slides)

2
Scientific Software for Neutron Scattering

• Software is a key enabler of an inelastic
  neutron spectrometer such as ARCS
• Some experiments are impossible owing to present
  software
• Many experiments produce better science with
  better software (optimize beamtime usage,
  experimental procedures tuned on-the-fly)
• Instrument specific (dozen or so instruments at
  the SNS)

3
ARCS Concept Data Analysis as a Web Service

• Data analysis is a service
• controlled by a web browser
• Computation is arranged by the server
• users web browser issues commands
• and receives results

4
XML and the Network

• XML-RPC is an open standard for remote procedure
  calls
• The users web browser issues commands to a
  server
• The server distributes the work to appropriate
  computers

XML-RPC
Database Server
XML-RPC
XML-RPC
XML-RPC
Web Server
Users Web Browser
Beowulf Cluster
5
Data Analysis as a Web Service

• The server can provide access to the best
  combination of hardware and software
• Experimental data and analysis codes reside on
  the servers, so little data bandwidth is needed
• Platform independent (a huge savings in effort!)
• Computing resources can be changed without
  affecting the user
• Clean separation of GUI from analysis code
• One web portal for all SNS instruments?

6
Levels of Code Development

• For altering existing Python scripts, entry
  barrier is very low.
• For writing new Python code, entry barrier is
  modest. Performance may be comparable to IDL or
  Matlab.
• If further improvement in computing performance
  is needed, a transition path to C is possible,
  although new effort is the required. The time
  when this transition takes place is flexible, and
  may be determined in part by the availability of
  software personnel.

7
Questions about SNS - Caltech Interactions

• Coordination of software projects at Caltech and
  SNS? Scope and scope management.
• Expectations of users for software support by SNS
  and instrument scientists.
• Consistency of GUI for SNS instruments? Single
  web portal?
• Who maintains the code?
• Standards for maintainable code with "open source
  coalition"?
• Issues with distributed computing. Lab policies,
  security, graphics, user permissions.
• Issues with releasing software to run on users'
  machines
• Status of storage and archiving of raw data by
  SNS?
• Institutional arrangements with the ORNL
  supercomputing center?
• On-line control of a neutron spectrometer.
  Technical and policy issues.

8
Coordination of SNS - Caltech Interactions

• SNS role is to produce and archive the data (one
  limiting case).
• ARCS effort for analysis of data with physics
  models (other limiting case).
• SNS to manage the coordination of software
  architecture. This includes acceptance of
  standards for programming, documentation, and
  maintenance. Is a national computing resource
  needed for this?
• Bring in the other instrument groups. SNS should
  require a software plan for each instrument.
• Explore role for Center for Advanced
  Computational Research as a data analysis center
  for SNS instruments.
• SNS to interface to national and international
  neutron facilities

9
User Interactions and Science?

• If larger role for ARCS software is planned, a
  working GUI will be necessary to sell the vision.
  
• Perhaps select a particular platform for
  implementing high-quality graphics as a demo and
  testbed.
• DOE labs will have to accommodate distributed
  computing because this is a major DOE initiative.
  
• Institutional arrangements with the ORNL
  supercomputing center should be pursued sooner
  than later, and may provide solutions to storage
  and archiving of raw data by SNS.