MICRA: A Model for the Development of Mission Critical Applications

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The growth of networked and distributed systems in several application domains has been explosive in the past few years. This has changed the way we reason about distributed systems in many ways. One issue of definitive importance is the following: what model to use for large-scale interactive or mission-critical applications? The MICRA project intends to study, propose, and validate an adequate model to address this problem.


This project aims to investigate, in the first place, the steps needed for the definition of a new model suitable for mission-critical applications. The crucial aspect is timing fault-tolerance in the context of real-time systems. We intend to formalize assumptions about system timeliness, and then develop what we call a Timing Failure Detector, in order to perfectly detect all violations of timeliness. There are several ways to treat the problem afterwards, but we plan to study the use of replication to mask timing faults. Previously known failure detectors were of the crash type only, our detectors are more accurate. Besides, replication has not been used previously in the context of timing faults, and as such, this approach is innovative. Our research will therefore concentrate on the definition of a set of basic services (a Timing Failure Detection Service -- TFDS, and a Replica Management Service -- RMS) which aim at providing the functionality just described, by means of a suitable programming interface, with provisions for timeliness specifications.

Approach and Methods

The project is structured around three main lines of action: i) basic research in the area of synchrony models for distributed systems, including the work required for the definition of a generic model suitable for MICRA; ii) definition of middleware architecures and platforms to support the development of mission-critical applications, including the definition of a Timing Failure Detection service and an adaptation or replication service; iii) implementation of a small demonstration prototype to validate the model and the services.

Progress and Results

The definition a a generic system model, the Timely Computing Base model, has been successfully accomplished during the first project year. Also some development work has been done, with results published in international workshops.


  • Paulo Verissimo, António Casimiro, “The Timely Computing Base”, Missing institution, Tech. Rep., May 1999. Technical Report DI/FCUL TR-99-2, Department of Informatics, University of Lisboa, May 1999


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