International Conference on Dependable Systems & Networks: Anchorage, Alaska, June 24-27 2008

Workshop on Architecting Dependable Systems (WADS 2008)

Rogerio de LemosUniversity ofKent, UKr. delemos@kent.ac. uk

Jean-Charles FabreLAAS-CNRS, France

jean-charlesfabre@laasfr

Cristina GacekNewcastle University, UKcristina.gacek@ncl.ac.uk

Abstract

This workshop summary gives a brief overview ofthe workshop on HArchitecting Dependable Systems"held in conjunction with DSN 2008. The main aim ofthis workshop is to promote cross-fertilization betweenthe software architecture and dependabilitycommunities. We believe that both ofthem will benefitfrom clarifying approaches that have been previouslytested and have succeeded as well as those that havebeen tried but have not yet been shown to besuccessful.

1. Introduction

This workshop will continue the initiative, whichstarted six years ago, of bringing together theinternational communities of dependability andsoftware architectures. The first workshop onArchitecting Dependable Systems was organisedduring the International Conference on SoftwareEngineering (leSE) 2002. Since then seven workshopswere organised and four books were published [1].This series of workshops have shown to be a fertileground for both communities to clarify previousapproaches, thus helping to promote new topical areaswhere the most promising research may lie, whileavoiding the reinvention of the wheel.

The main focus of this series of workshops is toaddress at the architectural level the structuring,modelling, and analysis of dependable softwaresystems. During DSN 2008 WADS the underlyingtheme will be Dependable Service OrientedArchitectures.

2. Architecting Dependable Systems

A major challenge lying ahead is how to builddependable systems from existing undependablecomponents and systems that were not originallydesigned to interact with each other. Thesecomponents and systems might not provide access to

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their internal designs and implementations, and theycan evolve independently of the overall system. Basedon these limitations, the delivery of correct service,and the justification of this ability, has to be obtainedfrom the interfaces and interactions of thesecomponents and systems. Architectural representationsof systems are effective in understanding broadersystem concerns by abstracting away from systemdetails, hence the trend of addressing dependability atthe architectural level, rather than late in thedevelopment process.

The reasoning about dependability at thearchitectural level can be addressed from differentperspectives:

• Architectural description languages, or acombination of different notations, can beemployed for modelling systems' architecturesin terms of their components and connectors,which might also include adaptors forpreventing architectural mismatches.

• For the provision of assurances that indeedfaults have been removed from the architecturalrepresentation, techniques like model checkingand theorem provers are employed together withmore traditional approaches, such asarchitectural inspections. Tests and faultinjection are also performed to check whetherthe implementation fulfils the architecturalspecification.

• Since it is difficult to remove all the faults froma system, provisions have to be made at thearchitectural level to tolerate residual faults.Efforts for this are in the form of structuringrules, as well as incorporating existing fault­tolerance techniques into architecturalabstractions.

• Architectural evaluation of systems shouldanalyse the impact that architectural decisionsmight have upon system failure. Architecturalfault injection and stochastic modeling are someof the means that have been used and are beingdeveloped.

DSN 2008: de Lemos et al.

International Conference on Dependable Systems & Networks: Anchorage, Alaska, June 24-27 2008

5. Committees

References

5.1 Workshop Organisers

5.2 Programme Committee

OrientedService

[1] Architecting Dependable Systems.http://www.cs.kent.ac.uk/people/staff/rdl/ADSFuture/index.htm.

Rogerio de Lemos (UK), Jean-Charles Fabre(France), Cristina Gacek (UK).

Roberto Baldoni (Italy), Felicita Di Giandomenico(Italy), Wolfgang Emmerich (UK), Peter Feiler (USA),Lars Grunske (Australia), Ricardo Jimenez Peris(Spain), Eliane Martins (Brazil), Nenad Medvidovic(USA), Henry Muccini (Italy), Priya Narasimhan(USA), Rick Schlichting (USA), Jean-Bernard Stefani(France), Elisabeth A Strunk (USA), Francois Taiani(UK), Aad van Moorsel (UK), Jie Xu (UK)

4.2. DependableArchitectures

This year we are building on the theme of serviceoriented architectures. Service oriented architectures(SOA) imply the organization and utilization ofdistributed capabilities that may be under the control ofdifferent ownership domains, while providing uniformmeans to offer, discover, interact with and usecapabilities to produce desired overall effects. Theyprovide new challenges and opportunities whenconsidering the architecting of dependable systems.The first question is to analyze whether well­established approaches still hold in this context. Thefault models and other basic assumptions regardingdependability may need to be revisited, giving rise tonovel architectural solutions for fault tolerance.Another issue is to consider what new approaches cannow be proposed that may not have been feasibleoutside the context of SOAs. The variouscontributions discussed during the workshop shouldprovide interesting insights on how to tackledependability problems in today's critical distributedsystems including both large-scale infrastructures andembedded devices.

For more program details please refer to the DSN2008 WADS web site[http://www.cs.kent.ac.uk/wads].

4. Workshop Program

4.1. Keynote Speaker

The aim of the workshop is to bring together thecommunities of software architectures anddependability to discuss the state of research andpractice when dealing with dependability issues at thearchitecture level. We are interested in submissionsfrom both industry and academia on all topics relatedto software architectures for dependable systems.These include, but are not limited to:

• Rigorous design: architectural descriptionlanguages; architectural patterns; formaldevelopment; architectural views; architecturalsupport for evolution; integrators (wrappers) fordependability; representation of faultassumptions;

• Verification & validation: architecturalinspection techniques; theorem proving; typechecking; model checking; architecture-basedfault injection; architecture-based conformancetesting; simulation;

• Fault tolerance: redundancy and diversity at thearchitectural level; error confinement;architectural monitoring; dynamically adaptablearchitectures; exception handling in softwarearchitectures; tolerating architecturalmismatches; architectural support for self­healing, self-repairing, self-stabilizing systems;support for adaptable fault tolerance;

• System evaluation: assurance baseddevelopment; dependability modeling andanalysis in software architectures; run-timechecks of dependability models at thearchitectural level; tradeoff betweendependability and cost;

• Enabling technologies: model drivenarchitectures; component based development;aspects oriented development; middleware;

• Application areas: safety-critical systems;critical infrastructures; mobile systems; serviceoriented architectures; embedded systems.

Rick Schlichting will be our keynote speaker. He isthe Director of Software Systems Research at AT&TLabs Research in Florham Park, NJ. He is well knownfor his work on distributed systems, highly dependablecomputing and fault tolerance, operating systems, andnetworks. The title of his talk will be "Keys toArchitecting Dependable SOAs".

3. Workshop Objectives and Topics

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