Job offer

Post-doc collaborative systems

Date: October 14th, 2019
Domain: Human-Computer Interaction
Topic: Post-doc on large scale real-time sharing of documents
Group: ExSitu, INRIA Saclay, Université Paris-Saclay
Location: Bâtiment 650 (Ada Lovelace)
Supervisor: Michel Beaudouin-Lafon, Professeur, U. Paris-Saclay
Lab director: Yannis Manoussakis

Post-doctoral position to work on the European-funded ERC project ONE ( on large scale real-time sharing of documents.


This post-doc is part of ERC project ONE (, directed by Michel Beaudouin-Lafon. The ambitious goal of ONE is to reinvent interactive systems based on a small number of unified principles, including the ability to share any digital content in real time. With unified and ubiquitous sharing, we can envision a new generation of applications that take advantage of our distributed digital environment, from smartphones to desktop and wall-size displays, from local storage to private and public cloud computing.

Webstrates is an advanced prototype created together with colleagues from Aarhus University in Denmark (Clemens Klokmose) and Telecom ParisTech in Paris (James Eagan) that demonstrates the power of real-time sharing of any web content and the use of transclusion for advanced software composition. The post-doc will be conducted in collaboration with colleagues at Inria (Marc Shapiro, Pascal Urso) and in Portugal (Nuno Preguiça, Carlos Baquero), who are experts in distributed systems, in particular CRDTs.


We are looking for a post-doctoral candidate to redesign and further explore the collaborative and distributed infrastructure of Webstrates . The key issues are:

  • Scalability and performance: Webstrates is based on Operational Transformation (OT). We are interested in alternatives to OT, most notably CRDTs (Conflict-free Replicated Datatypes), as well as in peer-to-peer architectures to support large numbers of users and high performance, including when the clients run on resource-constrained terminals such as smartphones or IoT devices.
  • Offline mode and versioning: Offline is needed in case of network outage; it is also useful when users do not want their changes to be immediately visible. However, offline mode can result in merge conflicts that cannot be resolved without user input. We are interested in combining versioning (as in Git or SVN) with the linear operation logs of OT and CRDT models, to support explicit versions created by users and implicit ones created when offline.
  • Access control/Constraints: We need more sophisticated and fine-grained access control than the current per-user and per-document read/write/no access rights. For example, we want to be able to restrict access to a part of a document, or to a subset of operations.
  • Interaction with history: The operations log is currently an untapped resource. From a user perspective, interacting with the history of documents has great potential. We are interested in aggregating and visualizing changes in order to facilitate navigation in the history.
Required Skills

The successful post-doctoral candidate should have a strong background and practical experience in distributed systems and consistency control algorithms, as well as an interest in interactive systems (human-computer interaction, ubiquitous computing). Good knowledge of the Web platform, protocols and languages is a plus.


Clemens N. Klokmose, James R. Eagan, Siemen Baader, Wendy Mackay, and Michel Beaudouin-Lafon. 2015. Webstrates: Shareable Dynamic Media. In Proceedings of the 28th Annual ACM Symposium on User Interface Software & Technology (UIST '15). ACM, New York, NY, USA, 280-290. DOI:


To apply send a resume, a letter of motivation and the names of two references to Contact us at this same address if you have any questions.