85 research outputs found
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Online Event Processing: Achieving Consistency Where Distributed Transactions Have Failed
Distributed transactions have failed as a mechanism for ensuring consistency across heterogeneous storage technologies in today's large-scale applications. Instead, we are witnessing the emergence of a programming model that relies on append-only event logs rather than transactions, and which we call OnLine Event Processing (OLEP) in contrast to OLTP. In this article we show that, although an event log is a very simple abstraction, applications that rely on such logs can efficiently provide strong consistency guarantees, such as atomicity and enforcing invariants, which are normally associated with ACID transactions. We provide case studies from real industrial data systems that have adopted the OLEP approach, demonstrating the practical advantages of building upon event logs.The Boeing Compan
The BaBar Event Building and Level-3 Trigger Farm Upgrade
The BaBar experiment is the particle detector at the PEP-II B-factory
facility at the Stanford Linear Accelerator Center. During the summer shutdown
2002 the BaBar Event Building and Level-3 trigger farm were upgraded from 60
Sun Ultra-5 machines and 100MBit/s Ethernet to 50 Dual-CPU 1.4GHz Pentium-III
systems with Gigabit Ethernet. Combined with an upgrade to Gigabit Ethernet on
the source side and a major feature extraction software speedup, this pushes
the performance of the BaBar event builder and L3 filter to 5.5kHz at current
background levels, almost three times the original design rate of 2kHz. For our
specific application the new farm provides 8.5 times the CPU power of the old
system.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, 1 eps figure, PSN MOGT00
High Level Trigger Configuration and Handling of Trigger Tables in the CMS Filter Farm
The CMS experiment at the CERN Large Hadron Collider is currently being commissioned and is scheduled to collect the first pp collision data in 2008. CMS features a two-level trigger system. The Level-1 trigger, based on custom hardware, is designed to reduce the collision rate of 40 MHz to approximately 100 kHz. Data for events accepted by the Level-1 trigger are read out and assembled by an Event Builder. The High Level Trigger (HLT) employs a set of sophisticated software algorithms, to analyze the complete event information, and further reduce the accepted event rate for permanent storage and analysis. This paper describes the design and implementation of the HLT Configuration Management system. First experiences with commissioning of the HLT system are also reported
Stepwise correlation of multivariate IoT event data based on first-order Markov chains
Correlating events in complex and dynamic IoT environments is a challenging
task not only because of the amount of available data that needs to be
processed but also due to the call for time efficient data processing. In this
paper, we discuss the major steps that should be performed in real- or near
real-time event management focusing on event detection and event correlation.
We investigate the adoption of a univariate change detection algorithm for
real-time event detection and we propose a stepwise event correlation scheme
based on a first-order Markov model. The proposed theory is applied on the
maritime domain and is validated through extensive experimentation with real
sensor streams originating from large-scale sensor networks deployed in a
maritime fleet of ships.Comment: arXiv admin note: substantial text overlap with arXiv:1803.0563
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