A scalable sequence encoding for collaborative editing

Brice Nédelec (1, 2) , Pascal Molli (1, 2) , Achour Mostefaoui (1, 2)

1 LS2N - équipe GDD - Gestion de Données Distribuées
2 LS2N - Laboratoire des Sciences du Numérique de Nantes

Distributed real-time editors made real-time editing easy for millions of users. However, main stream editors rely on Cloud services to mediate sessions raising privacy and scalability issues. Decentralized editors tackle privacy issues but scalability issues remains. We aim to build a decentralized editor that allows real-time editing anytime, anywhere, whatever is the number of participants. In this paper, we propose an approach based on a massively replicated sequence data structure that represents the shared document. We establish an original tradeoff on communication, time and space complexity to maintain this sequence over a network of browsers. We prove a sublinear upper bound on communication complexity while preserving an affordable time and space complexity. In order to validate this tradeoff, we built a full working editor and measured its performance on large scale experiments involving up till 600 participants. As expected, the results show a traffic increasing as O((log I)^2 ln R) where I is the number of insertions in the document, and R the number of participants.

Mots clés: replicated sequences; optimistic replication; real-time collaborative editing

Domaines: Informatique [cs]

Brice Nédelec, Pascal Molli, Achour Mostefaoui. A scalable sequence encoding for collaborative editing. Concurrency and Computation: Practice and Experience, 2021, ⟨10.1002/cpe.4108⟩. ⟨hal-01552799⟩