Kwiatkowska, M.

Sassone, V.

English

Southampton (e-Prints Soton)

GC2 Science for global ubiquitouscomputingMarta Kwiatkowska and Vladimiro SassoneHow many computers will you be using, wearing, or have installed in your body in 2020? How manyother computers will they be talking to? What will they be saying about you, doing for you or to you? Bythat time computers will be ubiquitous and globally connected. It is better not to count them individually,but to regard them collectively as a single Global Ubiquitous Computer (GUC). Who will then programthe GUC and how? Shall we be in control of it or even understand it?Let us imagine what life will be like in 2020. Smart homes will be equipped with autonomous, self-aware sensors, which will be capable of gathering information about their physical and digitalenvironment in order to recognize events, identify threats and take appropriate actions. Intelligent spaceswill be created by positioning sensors in the environment, all wirelessly connected and capable ofmonitoring working conditions and access to restricted parts of the buildings by automatically sensingradio tags worn on clothing. Medical treatment will be personalized, based on our genetic make-up andfactors such as age, and even delivered directly to our bodies by wearable devices.Does this seem too futuristic? Not so, if one considers the degree to which our lives are todaydependent on the internet, with access to grid and web services, and involve electronic devices that areever smaller, wireless and mobile. Already there are hundreds of embedded processors in modern cars,wireless ‘motes’ are deployed in environmental monitoring and industrial control, intelligent buildingsare a commercial reality and first successes have been reported with ‘medibots’ (nanoscale DNAcomputers capable of fighting cancer cells in a test tube).What are the essential features of an infrastructure to support such a scenario? Firstly, the internetalready enables global connectivity, by means of wired, radio and satellite communications; this impliesthe huge scale and complexity of the system, its highly distributed nature, mobility and continuedevolution. Secondly, each node on the network, either sensor or device, is capable of computation,communication and information processing, as it shrinks in size to the microscale, possibly nanoscale.Thirdly, the devices are increasingly self-aware, space and location conscious, able to interact with thesurrounding environment and exhibiting introspective behaviour. The size of the network, and thecomplexity of the interactions within it, demand that they be capable of cooperation, self-organization,self-diagnosis and self-repair. Finally, trust, privacy, security and dependability must be assured, as thecost of malfunction or breach of contract can be very high.The challenges this raises for both computer engineers and software designers are enormous. Therisks in the GUC are great: confidential medical records must never be leaked out to unauthorizedparties, drive-by-wire sensors must respond timely, and ‘medibots’ must be dispatched only if it can beguaranteed they work correctly. This is in sharp contrast with the frequent failures of current computersystems, which are orders of magnitude simpler than those we envisage for the GUC.So, how can we engineer a better GUC? Just as engineers rely on sciences of the physical world whenbuilding bridges, and use toolkits and theories from Physics and Mathematics to model and evaluatetheir designs, we need to develop a Science for Global Ubiquitous Computing, a fundamental theorydescribing ubiquitous computational phenomena. This will involve conceptual, mathematical andsoftware tools to inform and support the design process for ubiquitous systems, via models,programming languages, protocols, analysis techniques, verification tools and simulation. For example,the ‘medibots’ have been modelled using automata theory, temporal logic has been used to specify thesecurity of communication protocols and verification tools to detect their flaws, the pi-calculus modelsad hoc networks, and simulation is often used to analyse system performance. But we shall need manymore new concepts and tools. For instance, the theory must provide logics for trust and resource, andtools for the analysis of crypto-protocols and routing algorithms. It must also span several abstractionlevels to provide a flexible framework to harness complexity.9How can science make a difference?Is there a challenge for science at all? The scenarios we envision are, as illustrated above, typical futuristic,technological scenarios. Why cannot they be conquered as purely engineering, ‘hands-on’ tasks? Thedifficulty is that, without rigorous analysis of all the possible interactions between system components inthe design phase, it is all too easy to build systems that exhibit erroneous behaviour. The recent discoveryof security flaws in the 802.11 and Bluetooth® protocols can serve as a pertinent example.Of course, new technologies are bound to be experimental and, therefore, they run an intrinsic risk ofbeing flawed. There is nothing wrong with that, and it would be naive for us to advocate a future inwhich progress and market forces wait for scientists to give the green light. On the other hand, thescientific analysis of technological innovations allows us to understand solutions and their limitations,and is irreplaceable in a field like the GUC, which aims at applications with the potential to radicallychange the way we live. Enormous wealth, both in moral and physical terms, is currently entrusted tothe internet, and this can hardly be expected to change in the GUC future.Such analysis is the purpose of our challenge. It will underpin the design and engineering that is thefocus of our sister challenge Scalable Ubiquitous Computing Systems. Science is not design itself; thetwo are distinct, but sisters. They proceed with different timescales, tools, principles and milestones. Butthey only make sense as Grand Challenges when coupled together. We describe below two groups ofrelevant issues where the scientific, foundational approach will make a difference. The first group isconcerned with models.System and software architectures: We need models that inform the design of large software-intensive systems formed by ad hoc networks of heterogeneous components. The models mustsupport evolution, adaptive behaviour, loose coupling, autonomy, context-awareness, learning,security and more.Mobility, self- and context-awareness: We need calculuses and logics to formalize these notions.For example, how will systems attach a semantic meaning to information received from thecontexts met while roaming the global network, and how will they validate such information?Discrete/continuous models: We need to extend the current limited logics and formalisms toprovide predictive theories for hybrid systems (e.g. sensor networks) that feature continuousinputs, for example position and temperature, as well as discrete ones, for example roomnumber.Stochastic models: We need to adapt the current stochastic models (increasingly important fornetwork protocols) to provide compositional probabilistic analysis of the systems andsubsystems that make up the GUC.Cognition and interaction models: We need to model the cognitive aspects of the GUC, wherebysoftware devices learn during their lifetime, and learn how best to interact with humans inside asmart home.Knowledge, trust, security and privacy: Migrating devices will acquire information on which theywill base action, including interaction with potentially dangerous environments. We need to buildmodels for the acquisition, distribution, management and sharing of such knowledge, and inparticular how trust may be based upon it.The second group of issues is concerned with languages and tools.Programming language design: We need to isolate language features appropriate to the GUC,especially for complex disciplines of interaction. New data structures, for example based on XML,are of equal importance.Ubiquitous data: We need to understand how best to embed semi-structured data in programminglanguages and applications. This entails new type systems (for safety) and theories to underpinthe notions of ‘certified origin’ and ‘relevance’ of data items.Protocol design: We need to develop decentralized protocols for information exchange in ad hoc wirelessand sensor networks. These will likely contain elements of randomization to break the symmetrybetween the nodes, achieve scalability and improve performance under changing conditions.Algorithms for coordination, cooperation and autonomy: Interactions in the GUC invite a vision ofautonomous, mistrustful, selfish components, with no notion of common purpose and a ratherGrand Challenges in Computing – Research10faint notion of common welfare, running in some sort of equilibrium. We need to discover thealgorithms to underpin all this.Software technology and design support tools: We need to upgrade and advance the modelswhich underlie our current design technologies. They will involve new type systems, new formsof static analysis (including topographical analysis) and new validation/testing suites equippedfor the GUC.Verification techniques and technology: A marked success of computation theory has been theacceptance in industry of verification software tools, chiefly model checkers and automatedtheorem provers. We need to further advance research in this field so that every safety orbusiness critical system can be fully verified before deployment.Related activitiesThere are already a number of international and UK activities and projects that can provide support for theresearch outlined above. The EPSRC Network UK-UbiNet provides a forum for a broad spectrum ofactivities, from appliance design, through user experiences, to middleware and theory. It has already heldtwo workshops and plans a summer school in the near future. The EU-FET Global Computing initiative isa Framework Sixth programme focusing on the foundations of the GUC. In the UK, the Next Waveinitiative of the DTI focuses on products and technology transfer for ubiquitous computing; MobileBristol9 aims at developing user experiences with digital devices. The Equator project10 is anInterdisciplinary Research Collaboration which focuses on interleaving physical and digital interaction. Inthe USA, Berkeley’s Smart Dust originated the concept of ‘motes’, cubic millimetre miniature computingdevices, which are now being developed at Intel11 and Crossbow. In a recently founded UK–USpartnership, the Cambridge-MIT Institute (CMI), continues the research begun by project Oxygen.12Science for Global Ubiquitous Computing is related to several other Grand Challenges discussed at theConference in Newcastle (March 2004). The closest is Scalable Ubiquitous Computing Systems, a true sister challenge which shares our domain of interest. Indeed, the two held joint meetings inNewcastle and intend to collaborate in future, thus realizing what Christopher Strachey once famouslysaid:It has long been my personal view that the separation of practical andtheoretical work is artificial and injurious. Much of the practical work donein computing ... is unsound and clumsy because the people who do it havenot any clear understanding of the fundamental design principles of theirwork. Most of the abstract mathematical and theoretical work is sterilebecause it has no point of contact with real computing.There are also strong and useful relationships with at least three of the other challenges: DependableSystems Evolution, since the Global Ubiquitous Computer is highly dynamic and dependability is anessential requirement; In vivo–In silico, which shares with our challenge the aim of predictive modellingfor system dynamics and composition; and Memories for Life which aims to develop devices andrecordings to become part of the physical GUC. We also note that the new National Science Foundation’sScience of Design programme13 for internet and large-scale distributed systems, the infrastructure thatunderlies the GUC, addresses issues very similar to ours.First steps and ultimate goalsWe would like to begin by defining a ‘road map’: a conjectured path or group of paths leading to thegoals. The discussions at the Newcastle Conference led us to the conclusion that it is too early for this,Grand Challenges in Computing – Research119http://www.mobilebristol.co.uk/flash.html10http://machen.mrl.nott.ac.uk/home.html11http://www.intel.com/research/exploratory/motes.htm12http://oxygen.lcs.mit.edu13http://www.nsf.gov/pubs/2004/nsf04552/nsf04552.htmlargely because the GUC is an artefact that is still developing, and in unpredictable directions. Instead,we decided to focus on initial collaborative experiments, which may be called foothill projects, to help usestablish a case for such a road map. The projects arising from the panel discussions include:Assuring privacy, authentication and identity of medical records: An exemplar that enablesanytime/anywhere accessibility to medical records to doctors or patients in a provably securemanner will be developed. It will be based on sound models of trust- and privacy-ensuringtechnologies, and will consider human and digital communications of various kinds.Collaboration between security experts, researchers in human–computer interfaces, and themedical and legal professions will be needed.Rigorous process models for web services: We are increasingly dependent on web services forinformation, but are often frustrated with their unreliability and untimely responses. Acollaboration between researchers in process calculuses and middleware will address rigorousfoundations of web services, and will identify key coordination primitives for the GUC softwarearchitecture.Communications infrastructure protocols: As the GUC continues to evolve, we will see more andmore reliance on sensor and wireless networks in addition to the conventional internet (TCP/IP)protocols. New communication and routing protocols will have to be designed, implemented,verified and analysed. This project will involve networking experts, middleware developers andverification researchers.We aim to devise a science of the GUC: a set of concepts and theories that underpin and play a drivingrole in the design and engineering of the GUC and its components, which will assist in the modelling,analysis, diagnosis, evaluation and validation of the design. Our goals are:to develop a coherent informatic science whose concepts, calculuses,theories and automated tools allow descriptive and predictive analysis of theGUC at many levels of abstraction; and that every system and softwareconstruction, including languages, for the GUC shall employ only theseconcepts and calculuses, and be analysed and justified by these theoriesand tools.We envisage a 15-year time frame for this challenge to come to fruition, and much of the research willrequire global effort. It is, of course, possible that our challenge will never be entirely met. However,even partial successes will yield strong advantages. And it is ultimately the responsibility of computingresearch to place the GUC on as rigorous a basis as possible.Grand Challenges in Computing – Research12

GC2: Science for Global Ubiquitous Computing

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