6 Search Results for "Preguiça, Nuno"

Document
DOI: 10.4230/LIPIcs.OPODIS.2025.33
Resolving Conflicts with Grace: Dynamically Concurrent Universality

Authors: Petr Kuznetsov and Nathan Josia Schrodt

Published in: LIPIcs, Volume 361, 29th International Conference on Principles of Distributed Systems (OPODIS 2025)

Abstract
Synchronization is the major obstacle to scalability in distributed computing. Concurrent operations on the shared data engage in synchronization when they encounter a conflict, i.e., their effects depend on the order in which they are applied. Ideally, one would like to detect conflicts in a dynamic manner, i.e., adjusting to the current system state. Indeed, it is very common that two concurrent operations conflict only in some rarely occurring states. In this paper, we define the notion of dynamic concurrency: an operation employs strong synchronization primitives only if it has to arbitrate with concurrent operations, given the current system state. We then present a dynamically concurrent universal construction.
Cite as

Petr Kuznetsov and Nathan Josia Schrodt. Resolving Conflicts with Grace: Dynamically Concurrent Universality. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 33:1-33:29, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{kuznetsov_et_al:LIPIcs.OPODIS.2025.33,
  author =	{Kuznetsov, Petr and Schrodt, Nathan Josia},
  title =	{{Resolving Conflicts with Grace: Dynamically Concurrent Universality}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{33:1--33:29},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-409-3},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{361},
  editor =	{Arusoaie, Andrei and Onica, Emanuel and Spear, Michael and Tucci-Piergiovanni, Sara},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2025.33},
  URN =		{urn:nbn:de:0030-drops-252068},
  doi =		{10.4230/LIPIcs.OPODIS.2025.33},
  annote =	{Keywords: Universal Construction, Consensus, Dynamic Concurrency}
}
Document
DOI: 10.4230/LIPIcs.ECOOP.2025.4
Ensuring Convergence and Invariants Without Coordination

Authors: Dina Borrego, Nuno Preguiça, Elisa Gonzalez Boix, and Carla Ferreira

Published in: LIPIcs, Volume 333, 39th European Conference on Object-Oriented Programming (ECOOP 2025)

Abstract
The CAP theorem demonstrates a trade-off between consistency and availability (and, by extension, latency) in systems where network partitions are unavoidable, such as in cloud computing and local-first software. While adopting weak consistency can preserve availability, it may result in inconsistencies that compromise application correctness. Replicated data types provide a principled, coordination-free approach to guarantee convergence but do not consider application invariants. Existing methods for maintaining invariants in replicated systems either rely on coordination - undermining the benefits of weak consistency - or suffer from limited applicability. This paper introduces the No-Op framework, a generic approach for enforcing consistency without coordination while guaranteeing both convergence and invariant preservation. The core idea of the No-Op approach is to resolve conflicts among concurrent operations by prioritising one operation over the other according to programmer-defined conflict resolution policies. This prioritisation transforms the less-preferred operation into a no-side-effect operation, ensuring conflict-free execution. We formalise the model underlying the No-Op framework and introduce a replication protocol built upon it, accompanied by a formal proof of correctness for both the framework and the protocol. Furthermore, we demonstrate the framework’s applicability by showcasing the design of widely used replicated data types and the preservation of a wide range of application invariants.
Cite as

Dina Borrego, Nuno Preguiça, Elisa Gonzalez Boix, and Carla Ferreira. Ensuring Convergence and Invariants Without Coordination. In 39th European Conference on Object-Oriented Programming (ECOOP 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 333, pp. 4:1-4:29, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{borrego_et_al:LIPIcs.ECOOP.2025.4,
  author =	{Borrego, Dina and Pregui\c{c}a, Nuno and Gonzalez Boix, Elisa and Ferreira, Carla},
  title =	{{Ensuring Convergence and Invariants Without Coordination}},
  booktitle =	{39th European Conference on Object-Oriented Programming (ECOOP 2025)},
  pages =	{4:1--4:29},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-373-7},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{333},
  editor =	{Aldrich, Jonathan and Silva, Alexandra},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2025.4},
  URN =		{urn:nbn:de:0030-drops-232978},
  doi =		{10.4230/LIPIcs.ECOOP.2025.4},
  annote =	{Keywords: distributed systems, conflict resolution, RDTs, invariant preservation}
}
Document
Artifact
DOI: 10.4230/DARTS.11.2.1
Ensuring Convergence and Invariants Without Coordination (Artifact)

Authors: Dina Borrego, Nuno Preguiça, Elisa Gonzalez Boix, and Carla Ferreira

Published in: DARTS, Volume 11, Issue 2, Special Issue of the 39th European Conference on Object-Oriented Programming (ECOOP 2025)

Abstract
Our related paper introduces the No-Op framework, a generic approach for enforcing consistency without coordination while guaranteeing both convergence and invariant preservation. We implemented the core of the No-Op replication protocol in VeriFx [De Porre et al., 2023], a programming language for RDTs with automated proof capabilities. Alongside the algorithm implementation, we developed formal proofs to automatically verify the algorithm’s correctness properties when applied to specific data types or application implementations. This artifact bundles the implementation of the No-Op framework, various CRDTs [Marc Shapiro et al., 2011], and an eBay-like auction system akin to the RUBiS system [Emmanuel Cecchet et al., 2002] described in Section 5 of the paper. The artifact also provides a Dockerfile that can be used to reproduce the verification results (Section 4 of the paper).
Cite as

Dina Borrego, Nuno Preguiça, Elisa Gonzalez Boix, and Carla Ferreira. Ensuring Convergence and Invariants Without Coordination (Artifact). In Special Issue of the 39th European Conference on Object-Oriented Programming (ECOOP 2025). Dagstuhl Artifacts Series (DARTS), Volume 11, Issue 2, pp. 1:1-1:7, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@Article{borrego_et_al:DARTS.11.2.1,
  author =	{Borrego, Dina and Pregui\c{c}a, Nuno and Gonzalez Boix, Elisa and Ferreira, Carla},
  title =	{{Ensuring Convergence and Invariants Without Coordination (Artifact)}},
  pages =	{1:1--1:7},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2025},
  volume =	{11},
  number =	{2},
  editor =	{Borrego, Dina and Pregui\c{c}a, Nuno and Gonzalez Boix, Elisa and Ferreira, Carla},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.11.2.1},
  URN =		{urn:nbn:de:0030-drops-233447},
  doi =		{10.4230/DARTS.11.2.1},
  annote =	{Keywords: distributed systems, conflict resolution, RDTs, invariant preservation}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2025.32
The Free Termination Property of Queries over Time

Authors: Conor Power, Paraschos Koutris, and Joseph M. Hellerstein

Published in: LIPIcs, Volume 328, 28th International Conference on Database Theory (ICDT 2025)

Abstract
Building on prior work on distributed databases and the CALM Theorem, we define and study the question of free termination: in the absence of distributed coordination, what query properties allow nodes in a distributed (database) system to unilaterally terminate execution even though they may receive additional data or messages in the future? This completeness question is complementary to the soundness questions studied in the CALM literature. We also develop a new model based on semiautomata that allows us to bridge from the relational transducer model of the CALM papers to algebraic models that are popular among software engineers (e.g. CRDTs) and of increasing interest to database theory for datalog extensions and incremental view maintenance.
Cite as

Conor Power, Paraschos Koutris, and Joseph M. Hellerstein. The Free Termination Property of Queries over Time. In 28th International Conference on Database Theory (ICDT 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 328, pp. 32:1-32:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{power_et_al:LIPIcs.ICDT.2025.32,
  author =	{Power, Conor and Koutris, Paraschos and Hellerstein, Joseph M.},
  title =	{{The Free Termination Property of Queries over Time}},
  booktitle =	{28th International Conference on Database Theory (ICDT 2025)},
  pages =	{32:1--32:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-364-5},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{328},
  editor =	{Roy, Sudeepa and Kara, Ahmet},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2025.32},
  URN =		{urn:nbn:de:0030-drops-229736},
  doi =		{10.4230/LIPIcs.ICDT.2025.32},
  annote =	{Keywords: distributed systems, algebraic data models, coordination-free systems}
}
Document
DOI: 10.4230/LIPIcs.ECOOP.2023.9
VeriFx: Correct Replicated Data Types for the Masses

Authors: Kevin De Porre, Carla Ferreira, and Elisa Gonzalez Boix

Published in: LIPIcs, Volume 263, 37th European Conference on Object-Oriented Programming (ECOOP 2023)

Abstract
Distributed systems adopt weak consistency to ensure high availability and low latency, but state convergence is hard to guarantee due to conflicts. Experts carefully design replicated data types (RDTs) that resemble sequential data types and embed conflict resolution mechanisms that ensure convergence. Designing RDTs is challenging as their correctness depends on subtleties such as the ordering of concurrent operations. Currently, researchers manually verify RDTs, either by paper proofs or using proof assistants. Unfortunately, paper proofs are subject to reasoning flaws and mechanized proofs verify a formalization instead of a real-world implementation. Furthermore, writing mechanized proofs is reserved for verification experts and is extremely time-consuming. To simplify the design, implementation, and verification of RDTs, we propose VeriFx, a specialized programming language for RDTs with automated proof capabilities. VeriFx lets programmers implement RDTs atop functional collections and express correctness properties that are verified automatically. Verified RDTs can be transpiled to mainstream languages (currently Scala and JavaScript). VeriFx provides libraries for implementing and verifying Conflict-free Replicated Data Types (CRDTs) and Operational Transformation (OT) functions. These libraries implement the general execution model of those approaches and define their correctness properties. We use the libraries to implement and verify an extensive portfolio of 51 CRDTs, 16 of which are used in industrial databases, and reproduce a study on the correctness of OT functions.
Cite as

Kevin De Porre, Carla Ferreira, and Elisa Gonzalez Boix. VeriFx: Correct Replicated Data Types for the Masses. In 37th European Conference on Object-Oriented Programming (ECOOP 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 263, pp. 9:1-9:45, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{deporre_et_al:LIPIcs.ECOOP.2023.9,
  author =	{De Porre, Kevin and Ferreira, Carla and Gonzalez Boix, Elisa},
  title =	{{VeriFx: Correct Replicated Data Types for the Masses}},
  booktitle =	{37th European Conference on Object-Oriented Programming (ECOOP 2023)},
  pages =	{9:1--9:45},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-281-5},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{263},
  editor =	{Ali, Karim and Salvaneschi, Guido},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2023.9},
  URN =		{urn:nbn:de:0030-drops-182028},
  doi =		{10.4230/LIPIcs.ECOOP.2023.9},
  annote =	{Keywords: distributed systems, eventual consistency, replicated data types, verification}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2017.24
Non-Uniform Replication

Authors: Gonçalo Cabrita and Nuno Preguiça

Published in: LIPIcs, Volume 95, 21st International Conference on Principles of Distributed Systems (OPODIS 2017)

Abstract
Replication is a key technique in the design of efficient and reliable distributed systems. As information grows, it becomes difficult or even impossible to store all information at every replica. A common approach to deal with this problem is to rely on partial replication, where each replica maintains only a part of the total system information. As a consequence, a remote replica might need to be contacted for computing the reply to some given query, which leads to high latency costs particularly in geo-replicated settings. In this work, we introduce the concept of non- uniform replication, where each replica stores only part of the information, but where all replicas store enough information to answer every query. We apply this concept to eventual consistency and conflict-free replicated data types. We show that this model can address useful problems and present two data types that solve such problems. Our evaluation shows that non-uniform replication is more efficient than traditional replication, using less storage space and network bandwidth.
Cite as

Gonçalo Cabrita and Nuno Preguiça. Non-Uniform Replication. In 21st International Conference on Principles of Distributed Systems (OPODIS 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 95, pp. 24:1-24:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@InProceedings{cabrita_et_al:LIPIcs.OPODIS.2017.24,
  author =	{Cabrita, Gon\c{c}alo and Pregui\c{c}a, Nuno},
  title =	{{Non-Uniform Replication}},
  booktitle =	{21st International Conference on Principles of Distributed Systems (OPODIS 2017)},
  pages =	{24:1--24:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-061-3},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{95},
  editor =	{Aspnes, James and Bessani, Alysson and Felber, Pascal and Leit\~{a}o, Jo\~{a}o},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2017.24},
  URN =		{urn:nbn:de:0030-drops-86393},
  doi =		{10.4230/LIPIcs.OPODIS.2017.24},
  annote =	{Keywords: Non-uniform Replication, Partial Replication, Replicated Data Types, Eventual Consistency}
}
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