Transcript Times - Indico

JRA1-UK Meeting 5 July 2004, Abingdon, UK
www.eu-egee.org
Issues from the Spec
Steve Fisher / RAL
EGEE is a project funded by the European Union under contract IST-2003-508833
Contents
• Too many times
• DataBaseProducer
John's Spec, 5 July 2004 - 2
Times
• Times associated with a PrimaryProducer
 When data will be removed (to save space)
 Extra time to keep info if Consumer is going slow
 When it expects to publish again (related to intuitive concept of
latest)
• Note it could be the same producer or a new one
 The GRRP time out
 How long data will be kept after producer closes
 How long data will be kept after undeclare table
John's Spec, 5 July 2004 - 3
Proposal
• Associate just 2 times with a PrimaryProducer: LatestRP
and HistoryRP
 LatestRP
• is published with all tuples
• data are held after close for this time
• data are held after undeclare for this time
• Is used for the GRRP time out
 HistoryRP
• data discarded after this time but a new flag SignalSlowConsumer, if
set, will cause further inserts to generate an error, and data are not
discarded
• Physically all data are held for the same period in the
Producer but Latest Queries by default look back by the
published MinRP
John's Spec, 5 July 2004 - 4
Proposal for Secondaries
• Associate same 2 times with a SecondaryProducer
 close and undeclare take effect immediately
 LatestRP is associated with each tuple as set by the original
PrimaryProducer
 TerminationInterval
• Is used for the GRRP time out
 HistoryRP
• data discarded after this time but a new flag SignalSlowConsumer, if
set, will stop the data streaming in. This will eventually lead to a
message from an insert to the PrimaryProducers and a refusal to
accept more data at source
• Physically all data are held for the same period in the
Producer but Latest Queries by default look back by the
published LatestRP associated with the published tuple
John's Spec, 5 July 2004 - 5
DataBaseProducer
• Do we want to bring back a way of publishing via an
existing database?
 If DB has our structure we could just use it and pretend it is a
PrimaryProducer
 Is their a benefit in allowing people to publish any old table?
• It will only do one kind of query – like latest but people could fudge it if
the schema had a time field
• maybe the one query it supports should not be continuous, history or
latest but just call it a database query
• no retention periods
• needs a GRRP though
 Probably needs more thought
 Would be a good way to work with GridICE perhaps
John's Spec, 5 July 2004 - 6