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CMS Note
Report number	CMS-CR-2009-060
Title	Monitoring the CMS Data Acquisition System
Author(s)	Bauer, Gerry (MIT) ; Behrens, U (DESY) ; Biery, K (Fermilab) ; Branson, J (UC, San Diego) ; Cano, E (CERN) ; Cheung, H (Fermilab) ; Ciganek, M (CERN) ; Cittolin, S (CERN) ; Coarasa, J A (UC, San Diego ; CERN) ; Deldicque, C (CERN) ; Dusinberre, E (UC, San Diego) ; Erhan, S (CERN ; UCLA) ; Fortes Rodrigues, F (CEFET, Rio de Janeiro) ; Gigi, D (CERN) ; Glege, F (CERN) ; Gomez-Reino, R (CERN) ; Gutleber, J (CERN) ; Hatton, D (DESY) ; Laurens, J F (CERN) ; Lopez Perez, J A (CERN) ; Meijers, F (CERN) ; Meschi, E (CERN) ; Meyer, A (DESY ; CERN) ; Mommsen, R (Fermilab) ; Moser, R (CERN ; Vienna, Tech. U.) ; O'Dell, V (Fermilab) ; Oh, A (CERN) ; Orsini, L B (CERN) ; Patras, V (CERN) ; Paus, C (MIT) ; Petrucci, A (UC, San Diego) ; Pieri, M (UC, San Diego) ; Racz, A (CERN) ; Sakulin, H (CERN) ; Sani, M (UC, San Diego) ; Schieferdecker, P (CERN) ; Schwick, C (CERN) ; Shpakov, D (Fermilab) ; Simon, S (UC, San Diego) ; Sumorok, K (MIT) ; Zanetti, M. (CERN)
Publication	2010
Imprint	06 May 2009
Number of pages	10
In:	J. Phys.: Conf. Ser. 219 (2010) 022042
In:	17th International Conference on Computing in High Energy and Nuclear Physics, Prague, Czech Republic, 21 - 27 Mar 2009, pp.022042
DOI	10.1088/1742-6596/219/2/022042
Subject category	Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; CMS
Free keywords	ACQUISITION
Abstract	The CMS data acquisition system comprises O(20000) interdependent services that need to be monitored in near real-time. The ability to monitor a large number of distributed applications accurately and effectively is of paramount importance for robust operations. Application monitoring entails the collection of a large number of simple and composed values made available by the software components and hardware devices. A key aspect is that detection of deviations from a specified behaviour is supported in a timely manner, which is a prerequisite in order to take corrective actions efficiently. Given the size and time constraints of the CMS data acquisition system, efficient application monitoring is an interesting research problem. We propose an approach that uses the emerging paradigm of Web-service based eventing systems in combination with hierarchical data collection and load balancing. Scalability and efficiency are achieved by a decentralized architecture, splitting up data collections into regions of collections. An implementation following this scheme is deployed as the monitoring infrastructure of the CMS experiment at the Large Hadron Collider. All services in this distributed data acquisition system are providing standard web service interfaces via XML, SOAP and HTTP [15,22]. Continuing on this path we adopted WS-* standards implementing a monitoring system layered on top of the W3C standards stack. We designed a load-balanced publisher/subscriber system with the ability to include high-speed protocols [10,12] for efficient data transmission [11,13,14] and serving data in multiple data formats.
Copyright/License	Preprint: (License: CC-BY-4.0)

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