Last update:
Apr 1, 2000
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Process and Data Flow Control in KLOE
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Enrico Pasqualucci
INFN sez. di Roma
Speaker:
Enrico Pasqualucci
The core of the KLOE distributed event building system is a switched
network. Subevents coming from subdetectors are sent to different nodes of
a computing farm for the last stage of event building.
The online processes are distributed over a large set
of processors in this network.
All processes have to change
coherently their state of activity as a consequence of local
or remote commands.
A fast and reliable message system based on the SNMP protocol
has been developed. A command server has been implemented as a
non privileged daemon able to
respond to "set" and "get" queries on private SNMP variables.
This process is able to convert remote set operations into local commands
and to map automatically an SNMP subtree on a user-defined
set of process variables.
Process activity can be continuously monitored by remotely accessing
their variables by means of the command server.
Only the command server is involved in these operations,
without disturbing the process flow.
Subevents coming from subdetectors are sent to different nodes of
a computing farm for the last stage of event building.
Based on features of the SNMP protocol and of the KLOE message
system, the Data Flow Control System (DFC) is able to rapidly redirect
network traffic, keeping into accout the dynamics of the whole
DAQ system in order to assure coherent subevent addressing in
an asynchronous "push" architecture, without introducing dead time.
The KLOE DFC is currently working in the KLOE DAQ system. Its main
characteristics and performance are discussed.
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