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 user’s web browser issues commands and receives results

4. XML and the Network User’s Web Browser Web Server Database Server Beowulf Cluster XML-RPC is an open standard for remote procedure calls The user’s web browser issues commands to a server The server distributes the work to appropriate computers

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.