Blanc SIMI 2 - Sciences de l'information, de la matière et de l'ingénierie : Sciences de l’information, simulation

CRDTs for consistency without concurrency control in cloud and peer-to-peer systems – ConcoRDanT

Submission summary

Massive computing systems and their applications suffer from a fundamental tension between scalability and data consistency. Consistency implies synchronisation, which doesn't scale. To avoid synchronisation requires highly skilled programmers, makes applications complex and brittle, and is error-prone.

The ConcoRDanT project investigates a promising new approach that is simple, scales indefinitely, and provably ensures eventual consistency. A Commutative Replicated Data Type (CRDT) is a data type where all concurrent operations commute. If all replicas execute all operations, they converge; no complex concurrency control is required. We have shown in the past that CRDTs can replace existing techniques in a number of tasks where distributed users can update concurrently, such as cooperative editing, wikis, and version control. However CRDTs are not a universal solution and raise difficult issues (e.g., growth of meta-data).

The ConcoRDanT project engages in a systematic and principled study of CRDTs, to discover their power and limitations, both theoretical and practical. Its outcome will be a body of knowledge about CRDTs and a library of CRDT designs, and applications using them. We are hopeful that significant applications can be designed using appropriate combinations of CRDTs, elegantly reconciling scalability, consistency. This would be a significant breakthrough.

Project coordination

Marc SHAPIRO (INRIA - Siège) –

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


INRIA Paris-Rocquencourt INRIA - Siège
FCT/UNL Faculdade de Ciência e Tecnologia, Universidade Nova de Lisboa

Help of the ANR 316,742 euros
Beginning and duration of the scientific project: - 36 Months

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