Encontrados 12 documentos, a visualizar página 1 de 2
Assessing NoSQL databases for telecom applications
Cruz, Francisco; Gomes, Pedro; Oliveira, Rui Carlos Mendes de; Pereira, José13th Conference on Commerce and Enterprise Computing (CEC), 2011 IEEE ; The constant evolution of access technologies are turning Internet access more ubiquitous, faster, better and cheaper. In connection with the proliferation of Internet access, Cloud Computing is changing the way users look at data, moving from local applications and installations to remote services, accessible from any device. This new par...
Achieving eventual leader election in WS-discovery
Campos, Filipe; Pereira, José; Oliveira, Rui Carlos Mendes deFifth Latin-American Symposium on Dependable Computing (LADC) ; The Devices Profile for Web Services (DPWS) provides the foundation for seamless deployment, autonomous configuration, and joint operation for various computing devices in environments ranging from simple personal multimedia setups and home automation to complex industrial equipment and large data centers. In particular, WS-Discovery provides dyna...
An object mapping for the Cassandra distributed database
Gomes, Pedro; Pereira, José, 1973-; Oliveira, Rui Carlos Mendes deNew data management systems aimed at huge amounts of data, such as those pioneered by Google, Amazon, and Yahoo, have recently motivated a profound revolution in database management. These systems are characterized by simple data and query models and by their relaxed consistency, that contrasts with the ubiquitous and widely known relational and ACID model. These changes, in combination with the absence of a hi...
Worldwide consensus
Maia, Francisco; Matos, Miguel; Pereira, José, 1973-; Oliveira, Rui Carlos Mendes deConsensus is an abstraction of a variety of important challenges in dependable distributed systems. Thus a large body of theoretical knowledge is focused on modeling and solving consensus within different system assumptions. However, moving from theory to practice imposes compromises and design decisions that may impact the elegance, trade-offs and correctness of theoretical appealing consensus protocols. In t...
An epidemic approach to dependable key-value substrates
Matos, Miguel; Vilaça, Ricardo; Pereira, José, 1973-; Oliveira, Rui Carlos Mendes deThe sheer volumes of data handled by today's Internet services demand uncompromising scalability from the persistence substrates. Such demands have been successfully addressed by highly decentralized key-value stores invariably governed by a distributed hash table. The availability of these structured overlays rests on the assumption of a moderately stable environment. However, as scale grows with unprecedented...
A correlation-aware data placement strategy for key-value stores
Vilaça, Ricardo; Oliveira, Rui Carlos Mendes de; Pereira, José, 1973-Key-value stores hold the unprecedented bulk of the data produced by applications such as social networks. Their scalability and availability requirements often outweigh sacri cing richer data and pro- cessing models, and even elementary data consistency. Moreover, existing key-value stores have only random or order based placement strategies. In this paper we exploit arbitrary data relations easily expressed b...
A pragmatic protocol for database replication in interconnected clusters
Pereira, José, 1973-; Oliveira, Rui Carlos Mendes de; Grov, J.; Soares, L.; Correia Júnior, Alfrânio Tavares; Pedone, F.Multi-master update everywhere database replication, as achieved by protocols based on group communication such as DBSM and Postgres-R, addresses both performance and availability. By scaling it to wide area networks, one could save costly bandwidth and avoid large round-trips to a distant master server. Also, by ensuring that updates are safely stored at a remote site within transaction boundaries, disaster re...
Evaluating certification protocols in the partial database state machine
Sousa, António Luís Pinto Ferreira de; Moura, Francisco Coelho Soares; Pereira, José, 1973-; Oliveira, Rui Carlos Mendes dePartial replication is an alluring technique to ensure the reliability of very large and geographically distributed databases while, at the same time, offering good performance. By correctly exploiting access locality most transactions become confined to a small subset of the database replicas thus reducing processing, storage access and communication overhead associated with replication. The advantages of part...
Efficient epidemic multicast in heterogeneous networks
Pereira, José, 1973-; Oliveira, Rui Carlos Mendes de; Rodrigues, LuísThe scalability and resilience of epidemic multicast, also called probabilistic or gossip-based multicast, rests on its symmetry: Each participant node contributes the same share of bandwidth thus spreading the load and allowing for redundancy. On the other hand, the symmetry of gossiping means that it does not avoid nodes or links with less capacity. Unfortunately, one cannot naively avoid such symmetry withou...
Testing the dependability and performance of group communication based database...
Sousa, António Luís Pinto Ferreira de; Pereira, José, 1973-; Soares, L.; Correia Júnior, Alfrânio Tavares; Rocha, L.; Oliveira, Rui Carlos Mendes deDatabase replication based on group communication systems has recently been proposed as an efficient and resilient solution for large-scale data management. However, its evaluation has been conducted either on simplistic simulation models, which fail to assess concrete implementations, or on complete system implementations which are costly to test with realistic large-scale scenarios. This paper presents a tool...
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