Each day we see new and more powerful mobile devices with wireless communication capabilities. These are making the concept of ad hoc networking into a viable and promising possibility for ubiquitous information sharing.

However, the inherent characteristics of ad hoc networks bring up new challenges for which most conventional distributed systems don't provide an appropriate response. Namely, the lack of a pre-existing communication infrastructure, the high topological dynamism of these networks, the low bandwidth of wireless links (when compared to fixed networks) as well as the limited storage capacity of mobile devices. These are issues that strongly affect the efficiency of any distributed system intended to support information sharing in such environments.

Haddock-FS project addresses such aspects in the context of a ubiquitous information sharing by the use of a distributed file system. Namely, we intend to address the following challenges to the design and implementation of a distributed file system for ad hoc networks:

• Adequacy of the file system functionality to the semantics of file sharing being envisaged (for which some scenarios were described in the previous section);
• The consistency of replicated files must be handled in such a way that availability and performance are optimal while giving the user the power to decide how up-to-date his file replicas should be;
• The inherent hardware limitations that ad hoc networks and mobile devices have: memory constraints of mobile devices and the reduced bandwidth of wireless links, when compared to desktop computers and wired networks.

Efficient and Fault-Tolerant Update Commitment for Weakly Connected Replication

João Barreto, Paulo Ferreira

Proceedings of Euro-Par 2005 (Springer Verlag Lecture Notes in Computer Science), Lisboa, 2005

Haddock-FS: A Distributed File System for Mobile Ad-hoc Networks

João Pedro Barreto

M.Sc Thesis, Instituto Superior Técnico, 2004

Optimistic Consistency with Dynamic Version Vector Weighted Voting

João Barreto, Paulo Ferreira

Technical Report RT/007/2004, Inesc-ID Lisboa, 2004 (complements RT/004/2004)
Currently submitted for the 19th International Parallel & Distributed Processing Symposium

A Replicated File System for Resource Constrained Mobile Devices

João Barreto, Paulo Ferreira

IADIS Applied Computing International Conference, Lisboa, 2004

Information Sharing in Mobile Networks: a Survey on Replication Strategies

João Barreto

Technical Report RT/015/03, Inesc-ID Lisboa, 2003

A Distributed File System for Mobile Devices running Windows CE (Portuguese Version)

João Pedro Barreto

Final Year Project Report, Instituto Superior Técnico, 2002

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