Last updated 07.05.2004

PEssimistic, STrict, and Optimistic

The PESTO project resulted in a M.Sc. thesis with the title:

''A Mobility-Transparent Model for Consistency''

Not all those who wander are lost;
-- J.R.R.Tolkien (Lord of the Rings)

Project Description

This M.Sc. project is part of the AMIGOS project and aims at developing a distributed files system (file server and C runtime library) to investigate a new model for consistency as well as transactions for mobile-computing.

Existing distributed file systems employs different strategies for maintaining consistency between replicad files: either pessimistic, strict or optimistic replica control. In this report I will investigate a proposed (Transactions in Mobile Computing), model for consistency for mobile-computing that caters for use of and transisition between all three strategies.

The Thesis

The thesis was completed on December 2., 1996. It is available for download as DIKU report no. 96-3-7 in gzip'ed postscript format with figures from Chapter 5 and flow diagrams from appendices C and D available in tar'ed and gzip'ed Word 6.0 format

Now available in
PDF-format: pesto.pdf
- and -
HTML-format: pesto

Real PeStO is made of...

The Defence

The master defence took place at DIKU on January 6, 1997.


An article, available on-line A Model for Multi-Level Consistency, in gzip'ed postscript format or in PDF-format: artikel.pdf, describing the basic model was presented at the OOPSLA'96: Workshop on Object Replication and Mobile Computing (ORMC'96).


The article was part of the Advanced Internet Protocol Collected Course Readings at Copenhagen Business School (AIP'97 - Collected Course Readings or AIP'99 - Tentative Literature for Advanced Internet Protocols).

The article and the master thesis are in Aline BAGGIO's Bibliography on Mobile Computing and referenced in her PhD thesis "Adaptable and Mobile-Aware Distributed Objects" - part of the The Cadmium Project.

M.Sc. Student

Michael Garfield Sørensen (


If you think, this looks a lot like
TACO, Transparent Communication
then I can assure you, that it is no coincidence.

And special thanks go to
Birger Andersen

Thank You, Guys!

DistLab Links


Official PeStO Homepage (hasn't been updated recently)