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About

About

Paulo Sérgio Almeida is an Assistant Professor at the Department of Informatics at University of Minho, and a researcher at HASLab / INESC TEC. He obtained a MSc degree from University of Porto in 1994 and a PhD degree in Computer Science from Imperial College London in 1998. His research activities have been in the area of distributed systems, namely in causality tracking mechanisms, eventually consistent non-relational databases, fault-tolerant distributed aggregation algorithms, bloom filters, and distributed algorithms in graphs. In recent years the main focus of research has been on Conflict-free Replicated Data Types.

Interest
Topics
Details

Details

  • Name

    Paulo Sérgio Almeida
  • Cluster

    Computer Science
  • Role

    Senior Researcher
  • Since

    01st November 2011
002
Publications

2022

An oblivious observed-reset embeddable replicated counter

Authors
Weidner, M; Almeida, PS;

Publication
PaPoC@EuroSys 2022: Proceedings of the 9th Workshop on Principles and Practice of Consistency for Distributed Data, Rennes, France, April 5 - 8, 2022

Abstract
Embedding CRDT counters has shown to be a challenging topic, since their introduction in Riak Maps. The desire for obliviousness, where all information about a counter is fully removed upon key removal, faces problems due to the possibility of concurrency between increments and key removals. Previous state-based proposals exhibit undesirable reset-wins semantics, which lead to losing increments, unsatisfactorily solved through manual generation management in the API. Previous operation-based approaches depend on causal stability, being prone to unbounded counter growth under network partitions. We introduce a novel embeddable operation-based CRDT counter which achieves both desirable observed-reset semantics and obliviousness upon resets. Moreover, it achieves this while merely requiring FIFO delivery, allowing a tradeoff between causal consistency and faster information propagation, being more robust under network partitions. © 2022 Owner/Author.

2022

Exon: An Oblivious Exactly-Once Messaging Protocol

Authors
Kassam, Z; Almeida, PS; Shoker, A;

Publication
2022 31ST INTERNATIONAL CONFERENCE ON COMPUTER COMMUNICATIONS AND NETWORKS (ICCCN 2022)

Abstract

2019

Scalable eventually consistent counters over unreliable networks

Authors
Almeida, PS; Baquero, C;

Publication
DISTRIBUTED COMPUTING

Abstract

2019

Higher-order patterns in replicated data types

Authors
Leijnse, A; Almeida, PS; Baquero, C;

Publication
Proceedings of the 6th Workshop on Principles and Practice of Consistency for Distributed Data, PaPoC@EuroSys 2019, Dresden, Germany, March 25-28, 2019

Abstract
The design of Conflict-free Replicated Data Types traditionally requires implementing new designs from scratch to meet a desired behavior. Although there are composition rules that can guide the process, there has not been a lot of work explaining how existing data types relate to each other, nor work that factors out common patterns. To bring clarity to the field we explain underlying patterns that are common to flags, sets, and registers. The identified patterns are succinct and composable, which gives them the power to explain both current designs and open up the space for new ones. © 2019 Copyright held by the owner/author(s). Publication rights licensed to ACM.

2019

Efficient Synchronization of State-based CRDTs

Authors
Enes, V; Almeida, PS; Baquero, C; Leitao, J;

Publication
2019 IEEE 35TH INTERNATIONAL CONFERENCE ON DATA ENGINEERING (ICDE 2019)

Abstract

Supervised
thesis

2021

Beyong Distributed Transctions through Exactly-once Exchanges

Author
Ziad Ali Kassam

Institution
UM

2020

Implementation and Evaluation of Tagged Causal Multicast as a Rust Library

Author
Carlos Duarte Afonso Pereira

Institution
UM

2020

Beyond Distributed Transactions through Exactly-once Exchanges

Author
Ziad Ali Kassam

Institution
UM

2019

Beyong Distributed Transctions through Exactly-once Exchanges

Author
Ziad Ali Kassam

Institution
UM

2018

Deteção de Publicidade em Conteúdos de Difusão

Author
Tiago José Rodrigues Pereira

Institution
UP-FEUP