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Software Seminar Series (S3)

Luis Miguel Danielsson

Tuesday, September 24, 2019

10:45am Meeting room 302 (Mountain View), level 3

Luis Miguel Danielsson, PhD Student, Instituto IMDEA Software

Decentralized Stream Runtime Verification

Abstract:

We study the problem of decentralized monitoring of stream runtime verification specifications. Decentralized monitoring uses distributed monitors that communicate via a synchronous network, a communication setting common in many cyber-physical systems like automotive CPSs. Previous approaches to decentralized monitoring were restricted to logics like LTL logics that provide Boolean verdicts. We solve here the decentralized monitoring problem for the more general setting of stream runtime verification. Additionally, our solution handles network topologies while previous decentralized monitoring works assumed that every pair of nodes can communicate directly. We also introduce a novel property on specifications, called decentralized efficient monitorability, that guarantees that the online monitoring can be performed with bounded resources. Finally, we report the results of an empirical evaluation of an implementation and compare the expressive power and efficiency against state-of-the-art decentralized monitoring tools like Themis.


Time and place:
10:45am Meeting room 302 (Mountain View), level 3
IMDEA Software Institute, Campus de Montegancedo
28223-Pozuelo de Alarcón, Madrid, Spain


Manuel Bravo

Tuesday, September 17, 2019

10:45am Meeting room 302 (Mountain View), level 3

Manuel Bravo, Post-doctoral Researcher, Instituto IMDEA Software

Reconfigurable Atomic Transaction Commit

Abstract:

Modern data stores achieve scalability by partitioning data into shards and fault-tolerance by replicating each shard across several servers. A key component of such systems is a Transaction Certification Service (TCS), which atomically commits a transaction spanning multiple shards. Existing TCS protocols require 2f+1 crash-stop replicas per shard to tolerate f failures. In this work we present atomic commit protocols that require only f+1 replicas and reconfigure the system upon failures using an external reconfiguration service. We furthermore rigorously prove that these protocols correctly implement a recently proposed TCS specification. We present protocols in two different models--the standard asynchronous message-passing model and a model with Remote Direct Memory Access (RDMA), which allows a machine to access the memory of another machine over the network without involving the latter's CPU. Our protocols are inspired by a recent FARM system for RDMA-based transaction processing. Our work codifies the core ideas of FARM as distributed TCS protocols, rigorously proves them correct and highlights the trade-offs required by the use of RDMA.


Time and place:
10:45am Meeting room 302 (Mountain View), level 3
IMDEA Software Institute, Campus de Montegancedo
28223-Pozuelo de Alarcón, Madrid, Spain


Software Seminar Series (S3) - Primavera 2019