The Thomas Jefferson National Accelerator Facility control system uses a name server to reduce system response time and to minimize the impact of client name resolution on front-end computers. The control system is based on the Experimental Physics and Industrial Control System (EPICS), which uses name-based broadcasts to initiate data communication. By default, when EPICS process variables are requested by client applications, all front-end computers receive the broadcasts and perform name resolution processing against local channel name lists. The nameserver is used to offload the name resolution task to a single node. This processing, formerly done on all front-end computers, is now done only by the nameserver. In a control system with heavily loaded f ront-end computers and high peak client connection loads, a significant performance improvement is seen. This paper describes the name server in more detail, and discusses the strengths and weaknesses of making name resolution a centralized service.

Work performed for the U.S. Department of Energy by the Southeastern Universities Research Association under contract DE-AC05-84ER40150.

Authors: Joan Sage, Karen White, Matthew Bickley

Submitted for ICALEPCS 2001, San Jose, CA, Nov. 27-30 2001

Updated April 18, 2001

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