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About

I'm a MSc student at the Department of Informatics of the University of Minho, supervised by Professor Carlos Baquero, and hosted by HASLab, INESC TEC. I've been granted two internships from HASLab and from NOVA University of Lisbon to pursue my research, mainly within my MSc program and the EU FP7 SyncFree project, which was partially published at ECOOP PMLDC’16 workshop in Italy. I hold a Bachelor degree in Computer Science from University of Minho as well. I'm working on Distributed Systems (Eventual Consistency), but I also enjoy Formal Methods (although I know very little about them). I hope that, one day, I can work on both of them to make Distributed Systems work better..

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Details

Details

  • Name

    Vítor Manuel Duarte
  • Cluster

    Computer Science
  • Role

    Research Assistant
  • Since

    01st February 2016
001
Publications

2019

Efficient synchronization of state-based CRDTs

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

Publication
Proceedings - International Conference on Data Engineering

Abstract
To ensure high availability in large scale distributed systems, Conflict-free Replicated Data Types (CRDTs) relax consistency by allowing immediate query and update operations at the local replica, with no need for remote synchronization. State-based CRDTs synchronize replicas by periodically sending their full state to other replicas, which can become extremely costly as the CRDT state grows. Delta-based CRDTs address this problem by producing small incremental states (deltas) to be used in synchronization instead of the full state. However, current synchronization algorithms for delta-based CRDTs induce redundant wasteful delta propagation, performing worse than expected, and surprisingly, no better than state-based. In this paper we: 1) identify two sources of inefficiency in current synchronization algorithms for delta-based CRDTs; 2) bring the concept of join decomposition to state-based CRDTs; 3) exploit join decompositions to obtain optimal deltas and 4) improve the efficiency of synchronization algorithms; and finally, 5) experimentally evaluate the improved algorithms. © 2019 IEEE.

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
To ensure high availability in large scale distributed systems, Conflict-free Replicated Data Types (CRDTs) relax consistency by allowing immediate query and update operations at the local replica, with no need for remote synchronization. State-based CRDTs synchronize replicas by periodically sending their full state to other replicas, which can become extremely costly as the CRDT state grows. Delta-based CRDTs address this problem by producing small incremental states (deltas) to be used in synchronization instead of the full state. However, current synchronization algorithms for delta-based CRDTs induce redundant wasteful delta propagation, performing worse than expected, and surprisingly, no better than state-based. In this paper we: 1) identify two sources of inefficiency in current synchronization algorithms for delta-based CRDTs; 2) bring the concept of join decomposition to state-based CRDTs; 3) exploit join decompositions to obtain optimal deltas and 4) improve the efficiency of synchronization algorithms; and finally, 5) experimentally evaluate the improved algorithms.

2017

Borrowing an Identity for a Distributed Counter: Work in progress report

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

Publication
Proceedings of the 3rd International Workshop on Principles and Practice of Consistency for Distributed Data, PaPoC@EuroSys 2017, Belgrade, Serbia, April 23 - 26, 2017

Abstract
Conflict-free Replicated Data Types (CRDTs) are data abstractions (registers, counters, sets, maps, among others) that provide a relaxed consistency model called Eventual Consistency. Current designs for CRDT counters do not scale, having a size linear with the number of both active and retired nodes (i.e., nodes that leave the system permanently after previously manipulating the value of the counter). In this paper we present a new counter design called Borrow-Counter, that provides a mechanism for the retirement of transient nodes, keeping the size of the counter linear with the number of active nodes. © 2017 ACM.

2017

The Single-Writer Principle in CRDT Composition

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

Publication
Proceedings of the Programming Models and Languages for Distributed Computing on - PMLDC '17

Abstract

2017

Practical evaluation of the Lasp programming model at large scale

Authors
Meiklejohn, CS; Enes, V; Yoo, J; Baquero, C; Roy, PV; Bieniusa, A;

Publication
ACM International Conference Proceeding Series

Abstract
Programming models for building large-scale distributed applications assist the developer in reasoning about consistency and distribution. However, many of the programming models for weak consistency, which promise the largest scalability gains, have little in the way of evaluation to demonstrate the promised scalability. We present an experience report on the implementation and largescale evaluation of one of these models, Lasp, originally presented at PPDP '15, which provides a declarative, functional programming style for distributed applications. We demonstrate the scalability of Lasp's prototype runtime implementation up to 1024 nodes in the Amazon cloud computing environment. It achieves high scalability by uniquely combining hybrid gossip with a programming model based on convergent computation. We report on the engineering challenges of this implementation and its evaluation, specifically related to operating research prototypes in a production cloud environment. © 2017 Copyright held by the owner/author(s).