2001
Authors
Sousa, A; Pedone, F; Oliveira, R; Moura, F;
Publication
IEEE INTERNATIONAL SYMPOSIUM ON NETWORK COMPUTING AND APPLICATIONS, PROCEEDINGS
Abstract
This paper investigates the use of partial replication in the Database State Machine approach introduced earlier for fully replicated databases. It builds on the order and atomicity properties of group communication primitives to achieve strong consistency and proposes two new abstractions: Resilient Atomic Commit and Fast Atomic Broadcast. Even with atomic broadcast, partial replication requires a termination protocol such as atomic commit to ensure transaction atomicity. With Resilient Atomic Commit our termination protocol allows the commit of a transaction despite the failure of some of the participants. Preliminary, performance studies suggest that the additional cost of supporting partial replication can be mitigated through the use of Fast Atomic Broadcast.
2000
Authors
Pereira, J; Rodrigues, L; Oliveira, R;
Publication
19TH IEEE SYMPOSIUM ON RELIABLE DISTRIBUTED SYSTEMS - PROCEEDINGS
Abstract
Reliable multicast protocols can strongly simplify the design of distributed applications. However it is hard to sustain a high multicast throughput when groups are large and heterogeneous. In an attempt to overcome this limitation, previous work has focused on weakening reliability properties. In this paper we introduce a novel reliability model that exploits semantic knowledge to decide in which specific conditions messages can be purged without compromising application correctness. This model is based on the concept of message obsolescence: A message becomes obsolete when its content or purpose is overwritten by a subsequent message. We show that message obsolescence can be expressed in a generic way and can be used to configure the system to achieve higher multicast throughput.
2008
Authors
Dias, I; Oliveira, R; Frazao, O;
Publication
INNOVATION IN MANUFACTURING NETWORKS
Abstract
This work present and demonstrated an applications of artificial neural network approach in optical sensing. The conventional matrix method used in simultaneous measurement of strain and temperature with optical Bragg gratings is compared with artificial neural network approach. The alternative method is proposed for reduced the error.
2023
Authors
Brito, C; Ferreira, P; Portela, B; Oliveira, R; Paulo, J;
Publication
38TH ANNUAL ACM SYMPOSIUM ON APPLIED COMPUTING, SAC 2023
Abstract
We propose Soteria, a system for distributed privacy-preserving Machine Learning (ML) that leverages Trusted Execution Environments (e.g. Intel SGX) to run code in isolated containers (enclaves). Unlike previous work, where all ML-related computation is performed at trusted enclaves, we introduce a hybrid scheme, combining computation done inside and outside these enclaves. The conducted experimental evaluation validates that our approach reduces the runtime of ML algorithms by up to 41%, when compared to previous related work. Our protocol is accompanied by a security proof, as well as a discussion regarding resilience against a wide spectrum of ML attacks.
2023
Authors
Esteves, T; Macedo, R; Oliveira, R; Paulo, J;
Publication
2023 53RD ANNUAL IEEE/IFIP INTERNATIONAL CONFERENCE ON DEPENDABLE SYSTEMS AND NETWORKS WORKSHOPS, DSN-W
Abstract
We present DIO, a generic tool for observing inefficient and erroneous I/O interactions between applications and in-kernel storage systems that lead to performance, dependability, and correctness issues. DIO facilitates the analysis and enables near real-time visualization of complex I/O patterns for data-intensive applications generating millions of storage requests. This is achieved by non-intrusively intercepting system calls, enriching collected data with relevant context, and providing timely analysis and visualization for traced events. We demonstrate its usefulness by analyzing two production-level applications. Results show that DIO enables diagnosing resource contention in multi-threaded I/O that leads to high tail latency and erroneous file accesses that cause data loss.
2023
Authors
Esteves, T; Macedo, R; Oliveira, R; Paulo, J;
Publication
IEEE ACCESS
Abstract
We present DIO, a generic tool for observing inefficient and erroneous I/O interactions between applications and in-kernel storage backends that lead to performance, dependability, and correctness issues. DIO eases the analysis and enables near real-time visualization of complex I/O patterns for data-intensive applications generating millions of storage requests. This is achieved by non-intrusively intercepting system calls, enriching collected data with relevant context, and providing timely analysis and visualization for traced events. We demonstrate its usefulness by analyzing four production-level applications. Results show that DIO enables diagnosing inefficient I/O patterns that lead to poor application performance, unexpected and redundant I/O calls caused by high-level libraries, resource contention in multithreaded I/O that leads to high tail latency, and erroneous file accesses that cause data loss. Moreover, through a detailed evaluation, we show that, when comparing DIO's inline diagnosis pipeline with a similar state-of-the-art solution, our system captures up to 28x more events while keeping tracing performance overhead between 14% and 51%.
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