User feedback from CMS

Stephan Wynhoff and Emilio Meschi gave us the following feedback on the AIDA interfaces:

CMS is very interested in using a common interface, as AIDA, to data analysis objects, to exploit the flexibility to be independent of a given implementation. Their main interest is presently in histograms, and they like idea of having gravity bins as provided by the Anaphe implementation. There is also interest in the clouds, the unbinned histograms, for purpose of fitting on the original (unbinned) data, as well as for the flexibility to "rebin", i.e., adjust the borders for binning after some filling, once it can be seen which values for min/max would be ideal.

They request to have timing chart histograms, which keep the latest data (from last period in time or from last n events) and automatically when update, delete the previous data. These can be useful in the online environment for various monitoring purposes. A mechanism for automatically update histograms, when they are plotted is also requested for online application. There is interest in the online for the XML store. Size should be kept under control, since the XML format is used to move around histograms using messages. A too large message size could then cause network problems.

They like having an AIDA interface for tuples. Now CMS uses mainly Root tuples directly, and they would like to have an AIDA interface for Pool collections. However, whatever format for output is selected, it is desirable that ROOT is able to read it back. In the case of POOL this is not straightforward, but it could be done. For XML, PI could provide easily a small program which converts the file.

CMS is also interested in fitting, in particular if the interfaces are implemented using the C++ Minuit from SEAL. Fitting in batch jobs is done currently in ORCA using Nag through the Gemini interface. It would be nice to switch either to AIDA fitting or directly to the new Minuit in a rather short time.

Concerning interactivity, CMS has so far used ROOT or PAW. However, they are interested in a Python layer to access and interoperate between various tools.