Overvew of the contents of the volume "Semantic and logical foundations of global computing

Sannella, D.

Sassone, V.

English

Overview of the contents of the volume "Semantic and logical foundations of global computing

Southampton (e-Prints Soton)

Author's personal copyTheoretical Computer Science 389 (2007) 337–340www.elsevier.com/locate/tcsSemantic and logical foundations of global computing: Papers fromthe EU-FET global computing initiative (2001–2005)PrefaceGlobal computing refers to systems of interacting computational agents exhibiting the following characteristics:• they are autonomous, in that their activity is not centrally coordinated;• they are mobile, and their number, connectivity, and communication bandwidth may change during computation;• they have a limited knowledge of their working environment, and no global information about the state of thecomputation is available, nor is a globally trusted authority.These themes have been addressed in a series of international meetings, including Foundations of Wide AreaNetworks(FWAN2002),FoundationsofGlobalComputing(FGC2003,FGUC2004),andTrustedGlobalComputing(TGC 2005–2007). Notably, global computing has been the topic of EU funding initiatives (FET Global Computing2001–2005 and FET Global Computing II 2005–2009), and formed the basis of one of the UK Grand Challenges inComputing, Global Ubiquitous Computing (http://www-dse.doc.ic.ac.uk/Projects/UbiNet/GC). This volume collectsa representative selection of the best papers from the ﬁrst EU-FET initiative, as illustrated below.FET Global Computing (2001–2005) consisted of 13 projects clustered together in three main, essentially disjointgroups (cf. Fig. 1).Foundations of Networks and Large Distributed Systems. This cluster focused on global computing infrastructures,dealing with issues such as scheduling algorithms and mechanism design for resource sharing between interactingagents, speciﬁcation, veriﬁcation and reasoning about such systems. The cluster’s projects were: CRESSCO, CriticalResource Sharing for Cooperation in Complex Systems; DBGLOBE, A Data-Centric Approach to Global Computing;FLAGS, Foundational Aspects of Global Computing Systems; and SOCS, Societies of Computees.CRESSCO researched foundational aspects of managing critical resources (such as bandwidth, frequency, energy,processor time) in GC infrastructures connecting very large numbers of independent, possibly mobile and selﬁsh agententities. FLAGS aimed at a general set of design principles and mechanisms for global computing systems of suchagents competing for resources. CRESSCO and FLAGS pioneered the application of economic game and auctiontheories to resource sharing in distributed computing systems. DBGLOBE focused on extending current databasetechnology to address data management requirements in large-scale networks of mobile entities. Their approach isdata-centric, and developed a new language for integrating documents and queries, called Active XML. Finally, SOCSinvestigated computational and logical models for analysis and veriﬁcation of societies of agents, with emphasis ontechniques and models adapted from logic programming.Analysis of Systems and Security. The focus here is on formal techniques such as type theory, proof-carrying code, andformal models for trust management for validating system properties of safety and security. The cluster was composedof: DART, Dynamic Assembly, Reconﬁguration and Type Theory; MRG, Mobile Resource Guarantees; MYTHS,Models and Types for Security in Mobile Distributed Systems; PROFUNDIS, Proofs of Functionality for MobileDistributed Systems; and SECURE, Secure Environment for Collaboration among Ubiquitous Roaming Entities.0304-3975/$ - see front matter c   2007 Elsevier B.V. All rights reserved.doi:10.1016/j.tcs.2007.09.017Author's personal copy338 Editorial / Theoretical Computer Science 389 (2007) 337–340Fig. 1. EU-FET Global Computing projects and their clustering.DART developed formalisms and techniques for supporting arbitrary interleaving of type-checking, meta-programming, and normal computational activities while retaining safety; a notable outcome is their work on “smartrecompilation.” MRG set out to extend the concept of proof-carrying code to include guarantees of resource usage,both in programmer-level languages and in low-level assembly and byte code. MYTHS explored type-based theoriesof security for mobile and distributed systems, for the analysis of security protocols, and for the type-orientedmanipulation of XML data. Both very small sized, MRG and MYTHS achieved signiﬁcant breakthroughs in theirrespective ﬁelds. PROFUNDIS exploited formal models and veriﬁcation to explore key issues in mobile distributedsystems, such as security and authentication, access rights control and resource management, as well as automaticsupportforthedesignandimplementationofsuchfeatures.Theveriﬁcationandtestingtoolsproducedby PROFUNDISare regarded as valuable assets for the community. Finally, SECURE proposed a novel formal model of security basedon the notion of trust and of algorithms for the dynamic management of trust, forming the so-called SECURE trustengine.Languages and Programming Environments. This third cluster has used and extended theoretical foundations suchas those developed in the previous two clusters for designing suitable software tools and frameworks. The cluster’sprojects were: AGILE, Architectures for Mobility; DEGAS, Design Environments for Global Applications; MIKADO,Mobile Calculi Based on Domains; and PEPITO, Peer-to-Peer Implementation and Theory.AGILE explored a UML-based architectural approach to software engineering for mobile systems, includingtheoretical foundations as well as pragmatic techniques for deriving software architectural components correspondingto UML models. DEGAS derived speciﬁc process-algebra-based performance models from annotated UMLapplication models both as a design principle and as an implementation technique. They delivered a set of tools formechanising the process, notably the environment “Choreographer”, which was very well received by the community.MIKADO – which can also be seen as belonging to the ‘Analysis’ cluster – researched formal programming modelsfor global computing based on the notion of “domain”, and delivered new prototype programming languages andruntime environments. Finally, PEPITO investigated the foundations of scalable distributed computing based on thepeer-to-peer computing paradigm, exploring algorithms and programming languages. They developed a generic,language-independent distribution platform for P2P computing which provides a practical proof for server-lesssystems.As can be observed in Fig. 1, a theme that cuts across clusters was security and resource management.Author's personal copyEditorial / Theoretical Computer Science 389 (2007) 337–340 339An invitation to readThe following papers are included in this special issue. Some are extended versions of papers that were publishedin the proceedings of TGC 2005, which was published by Springer as volume 3705 in the Lecture Notes in ComputerScience series, edited by Rocco de Nicola and Davide Sangiorgi, and other conferences. All have been refereed tojournal standard.Formalising Java RMI with Explicit Code Mobility, by Alexander Ahern and Nobuko Yoshida. This paperformalises the key components of Java Remote Method Invocation (RMI) as a distributed and object-oriented processalgebra, with primitives for distributed programming and explicit code mobility. The formalisation captures the crucialprocesses of serialising and unserialising data, passing data, code and class deﬁnitions across the network, and thesemantics of synchronisation operations. The formalisation is shown to be type-safe, and it is used to prove thecorrectness of several optimisations for distributed programs. This work contributes to the Analysis of Systems activity.A Program Logic for Resources, by David Aspinall, Lennart Beringer, Martin Hofmann, Hans-Wolfgang Loidl,and Alberto Momigliano. This paper deﬁnes a sound and complete logic for proving statements about resourceconsumption in a subset of the Java Virtual Machine Language, designed to be used in a proof-carrying code scenarioin which mobile programs are equipped with formal evidence that they have good resource behaviour. A second logic,used to express termination, is also shown to be sound and complete. Both logics and all meta-theoretical results havebeen formalised in the Isabelle/HOL theorem prover as part of a prototype implementation of proof-carrying codeapplied to resource bounds in the MRG project.ASemanticFrameworkforOpenProcesses,byPaoloBaldan,AndreaBracciali,andRobertoBruni.TakingtheleadfromtheideathatGlobalComputingsystems–andmoregenerallyopennetworks–canbeformalisedascoordinators,i.e. terms with holes to be plugged in by components and further coordinators, the authors set out to develop a generaltheory of such terms. They ﬁrst use symbolic transition systems to describe coordinators operationally, and thenpresent a novel bisimulation semantics that preserves the coordinators’ openness, and fully accounts for it. This worksits quite well with the research approaches of both the clusters Languages and Programming Environments andAnalysis of Systems and Security.A Formal Semantics for Protocol Narrations, by S´ ebastien Briais and Uwe Nestmann. Protocol narrations areintuitive descriptions of crypto-protocols as sequences of encrypted exchanges among participants. The authorspropose a formal operational semantics for protocol narrations and – on the basis of such a semantics – explain andjustify a natural and precise translation of narrations into spi-calculus which led to the realisation of automated toolsand the analysis of case studies, also presented in the paper. This work exempliﬁes quite signiﬁcantly the Languagesand Programming Environments cluster.A Framework for Analyzing Probabilistic Protocols and its Application to the Partial Secrets Exchange, byKonstantinos Chatzikokolakis and Catuscia Palamidessi. This paper presents a new probabilistic process algebrawhich extends the pi-calculus with probabilistic constructs in order to specify randomised security protocols. Itssemantics is given in terms of Segala–Lynch probabilistic automata, and a may-testing pre-order between processesis deﬁned. This is used to specify and verify the correctness of the Partial Secrets Exchange protocol. This is anothercontribution to the Analysis of Systems activity.The Complexity of Fixed Point Models of Trust in Distributed Networks, by Karl Krukow and Andrew Twigg.Global trust in the presence of delegation of authority can be modelled as a ﬁxed point of local policies taken ideallyover the entire global network. This paper explores distributed algorithms for computing or approximating global trustefﬁciently, and determines their lower bounds and computational complexity. The key notion adopted by the authorsis that of distributed proof-carrying request. This work was produced in the context of the SECURE project in theAnalysis of Systems and Security cluster.AcknowledgementsWe wish to thank the colleagues who acted as referees for this volume. They are: Chiara Bodei, Frank de Boer,Roberto Bruni, Michele Bugliesi, Derek Dreyer, Sergio Maffeis, Alberto Momigliano, Uwe Nestmann, Jo¨ el Ouaknine,Paula Quaglia, Julian Rathke, Bernard Reus, Peter Sewell, Martin Steffen, David Walker, and Nobuko Yoshida. Ourdescription of the EU-FET GC clusters is inspired by the EU ﬁnal report for FET GC (cf. http://cordis.europa.eu/ist/fet/gc.htm).Author's personal copy340 Editorial / Theoretical Computer Science 389 (2007) 337–340Donald Sannella University of Edinburgh,Edinburgh, United KingdomE-mail address: dts@inf.ed.ac.uk.Vladimiro SassoneUniversity of Southampton,Southampton, United KingdomE-mail address: vs@ecs.soton.ac.uk.  Corresponding editor.

Semantic and logical foundations of global computing: Papers from the EU-FET global computing initiative (2001–2005)

Sannella, Donald

Sassone, Vladimiro

Elsevier - Publisher Connector 

Semantic and logical foundations of global computing: Papers from the EU-FET global computing initiative (2001–2005) 

Theoretical Computer Science 389 (2007) 337–340
www.elsevier.com/locate/tcs
Semantic and logical foundations of global computing: Papers from
the EU-FET global computing initiative (2001–2005)
Preface
Global computing refers to systems of interacting computational agents exhibiting the following characteristics:
• they are autonomous, in that their activity is not centrally coordinated;
• they are mobile, and their number, connectivity, and communication bandwidth may change during computation;
• they have a limited knowledge of their working environment, and no global information about the state of the
computation is available, nor is a globally trusted authority.
These themes have been addressed in a series of international meetings, including Foundations of Wide Area
Networks (FWAN 2002), Foundations of Global Computing (FGC 2003, FGUC 2004), and Trusted Global Computing
(TGC 2005–2007). Notably, global computing has been the topic of EU funding initiatives (FET Global Computing
2001–2005 and FET Global Computing II 2005–2009), and formed the basis of one of the UK Grand Challenges in
Computing, Global Ubiquitous Computing (http://www-dse.doc.ic.ac.uk/Projects/UbiNet/GC). This volume collects
a representative selection of the best papers from the first EU-FET initiative, as illustrated below.
FET Global Computing (2001–2005) consisted of 13 projects clustered together in three main, essentially disjoint
groups (cf. Fig. 1).
Foundations of Networks and Large Distributed Systems. This cluster focused on global computing infrastructures,
dealing with issues such as scheduling algorithms and mechanism design for resource sharing between interacting
agents, specification, verification and reasoning about such systems. The cluster’s projects were: CRESSCO, Critical
Resource Sharing for Cooperation in Complex Systems; DBGLOBE, A Data-Centric Approach to Global Computing;
FLAGS, Foundational Aspects of Global Computing Systems; and SOCS, Societies of Computees.
CRESSCO researched foundational aspects of managing critical resources (such as bandwidth, frequency, energy,
processor time) in GC infrastructures connecting very large numbers of independent, possibly mobile and selfish agent
entities. FLAGS aimed at a general set of design principles and mechanisms for global computing systems of such
agents competing for resources. CRESSCO and FLAGS pioneered the application of economic game and auction
theories to resource sharing in distributed computing systems. DBGLOBE focused on extending current database
technology to address data management requirements in large-scale networks of mobile entities. Their approach is
data-centric, and developed a new language for integrating documents and queries, called Active XML. Finally, SOCS
investigated computational and logical models for analysis and verification of societies of agents, with emphasis on
techniques and models adapted from logic programming.
Analysis of Systems and Security. The focus here is on formal techniques such as type theory, proof-carrying code, and
formal models for trust management for validating system properties of safety and security. The cluster was composed
of: DART, Dynamic Assembly, Reconfiguration and Type Theory; MRG, Mobile Resource Guarantees; MYTHS,
Models and Types for Security in Mobile Distributed Systems; PROFUNDIS, Proofs of Functionality for Mobile
Distributed Systems; and SECURE, Secure Environment for Collaboration among Ubiquitous Roaming Entities.
0304-3975/$ - see front matter c© 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.tcs.2007.09.017
338 Editorial / Theoretical Computer Science 389 (2007) 337–340
Fig. 1. EU-FET Global Computing projects and their clustering.
DART developed formalisms and techniques for supporting arbitrary interleaving of type-checking, meta-
programming, and normal computational activities while retaining safety; a notable outcome is their work on “smart
recompilation.” MRG set out to extend the concept of proof-carrying code to include guarantees of resource usage,
both in programmer-level languages and in low-level assembly and byte code. MYTHS explored type-based theories
of security for mobile and distributed systems, for the analysis of security protocols, and for the type-oriented
manipulation of XML data. Both very small sized, MRG and MYTHS achieved significant breakthroughs in their
respective fields. PROFUNDIS exploited formal models and verification to explore key issues in mobile distributed
systems, such as security and authentication, access rights control and resource management, as well as automatic
support for the design and implementation of such features. The verification and testing tools produced by PROFUNDIS
are regarded as valuable assets for the community. Finally, SECURE proposed a novel formal model of security based
on the notion of trust and of algorithms for the dynamic management of trust, forming the so-called SECURE trust
engine.
Languages and Programming Environments. This third cluster has used and extended theoretical foundations such
as those developed in the previous two clusters for designing suitable software tools and frameworks. The cluster’s
projects were: AGILE, Architectures for Mobility; DEGAS, Design Environments for Global Applications; MIKADO,
Mobile Calculi Based on Domains; and PEPITO, Peer-to-Peer Implementation and Theory.
AGILE explored a UML-based architectural approach to software engineering for mobile systems, including
theoretical foundations as well as pragmatic techniques for deriving software architectural components corresponding
to UML models. DEGAS derived specific process-algebra-based performance models from annotated UML
application models both as a design principle and as an implementation technique. They delivered a set of tools for
mechanising the process, notably the environment “Choreographer”, which was very well received by the community.
MIKADO – which can also be seen as belonging to the ‘Analysis’ cluster – researched formal programming models
for global computing based on the notion of “domain”, and delivered new prototype programming languages and
runtime environments. Finally, PEPITO investigated the foundations of scalable distributed computing based on the
peer-to-peer computing paradigm, exploring algorithms and programming languages. They developed a generic,
language-independent distribution platform for P2P computing which provides a practical proof for server-less
systems.
As can be observed in Fig. 1, a theme that cuts across clusters was security and resource management.
Editorial / Theoretical Computer Science 389 (2007) 337–340 339
An invitation to read
The following papers are included in this special issue. Some are extended versions of papers that were published
in the proceedings of TGC 2005, which was published by Springer as volume 3705 in the Lecture Notes in Computer
Science series, edited by Rocco de Nicola and Davide Sangiorgi, and other conferences. All have been refereed to
journal standard.
Formalising Java RMI with Explicit Code Mobility, by Alexander Ahern and Nobuko Yoshida. This paper
formalises the key components of Java Remote Method Invocation (RMI) as a distributed and object-oriented process
algebra, with primitives for distributed programming and explicit code mobility. The formalisation captures the crucial
processes of serialising and unserialising data, passing data, code and class definitions across the network, and the
semantics of synchronisation operations. The formalisation is shown to be type-safe, and it is used to prove the
correctness of several optimisations for distributed programs. This work contributes to the Analysis of Systems activity.
A Program Logic for Resources, by David Aspinall, Lennart Beringer, Martin Hofmann, Hans-Wolfgang Loidl,
and Alberto Momigliano. This paper defines a sound and complete logic for proving statements about resource
consumption in a subset of the Java Virtual Machine Language, designed to be used in a proof-carrying code scenario
in which mobile programs are equipped with formal evidence that they have good resource behaviour. A second logic,
used to express termination, is also shown to be sound and complete. Both logics and all meta-theoretical results have
been formalised in the Isabelle/HOL theorem prover as part of a prototype implementation of proof-carrying code
applied to resource bounds in the MRG project.
A Semantic Framework for Open Processes, by Paolo Baldan, Andrea Bracciali, and Roberto Bruni. Taking the lead
from the idea that Global Computing systems – and more generally open networks – can be formalised as coordinators,
i.e. terms with holes to be plugged in by components and further coordinators, the authors set out to develop a general
theory of such terms. They first use symbolic transition systems to describe coordinators operationally, and then
present a novel bisimulation semantics that preserves the coordinators’ openness, and fully accounts for it. This work
sits quite well with the research approaches of both the clusters Languages and Programming Environments and
Analysis of Systems and Security.
A Formal Semantics for Protocol Narrations, by Se´bastien Briais and Uwe Nestmann. Protocol narrations are
intuitive descriptions of crypto-protocols as sequences of encrypted exchanges among participants. The authors
propose a formal operational semantics for protocol narrations and – on the basis of such a semantics – explain and
justify a natural and precise translation of narrations into spi-calculus which led to the realisation of automated tools
and the analysis of case studies, also presented in the paper. This work exemplifies quite significantly the Languages
and Programming Environments cluster.
A Framework for Analyzing Probabilistic Protocols and its Application to the Partial Secrets Exchange, by
Konstantinos Chatzikokolakis and Catuscia Palamidessi. This paper presents a new probabilistic process algebra
which extends the pi-calculus with probabilistic constructs in order to specify randomised security protocols. Its
semantics is given in terms of Segala–Lynch probabilistic automata, and a may-testing pre-order between processes
is defined. This is used to specify and verify the correctness of the Partial Secrets Exchange protocol. This is another
contribution to the Analysis of Systems activity.
The Complexity of Fixed Point Models of Trust in Distributed Networks, by Karl Krukow and Andrew Twigg.
Global trust in the presence of delegation of authority can be modelled as a fixed point of local policies taken ideally
over the entire global network. This paper explores distributed algorithms for computing or approximating global trust
efficiently, and determines their lower bounds and computational complexity. The key notion adopted by the authors
is that of distributed proof-carrying request. This work was produced in the context of the SECURE project in the
Analysis of Systems and Security cluster.
Acknowledgements
We wish to thank the colleagues who acted as referees for this volume. They are: Chiara Bodei, Frank de Boer,
Roberto Bruni, Michele Bugliesi, Derek Dreyer, Sergio Maffeis, Alberto Momigliano, Uwe Nestmann, Joe¨l Ouaknine,
Paula Quaglia, Julian Rathke, Bernard Reus, Peter Sewell, Martin Steffen, David Walker, and Nobuko Yoshida. Our
description of the EU-FET GC clusters is inspired by the EU final report for FET GC (cf. http://cordis.europa.eu/ist/
fet/gc.htm).
340 Editorial / Theoretical Computer Science 389 (2007) 337–340
Donald Sannella∗
University of Edinburgh,
Edinburgh, United Kingdom
E-mail address: dts@inf.ed.ac.uk.
Vladimiro Sassone
University of Southampton,
Southampton, United Kingdom
E-mail address: vs@ecs.soton.ac.uk.
∗ Corresponding editor.


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