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...rallel and/or distributed system. A tuple is, however, a very point-wise abstraction, and applications often need to express relationships articulated across the physical environment through which the computational system is distributed. There is thus a need for coordination models and languages that raise the level of abstraction from the single tuple to a spatial structure of tuples, without forgetting the possibility that such a structure, as well as being distributed, may also be highly dynamic and mobile. Such spatial coordination models have been developed in a number of previous papers [29,17,18,24]. These span multiple application contexts, such as pervasive computing, where mobility, large system scale, and/or situatedness invite the coordination space to be interpreted as a distributed substrate for spatial data structures. These models enhance the standard tuple-space settings with primitives for spreading tuples from nodes to their neighbors, and letting them M. Sirjani (Ed.): COORDINATION 2012, LNCS 7274, pp. 212–229, 2012. c© IFIP International Federation for Information Processing 2012 Linda in Space-Time 213 affect (or be affected by) the context of neighbors. Iterative spreadin...

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...ome space, such that the difficulty of moving information between devices is strongly dependent on the distance separating them. Examples of spatial computers include sensor networks, mobile ad-hoc networks (MANETs), colonies of engineered bacteria, robotic swarms, and pervasive computing systems. Aggregate-level programming and control of such systems is an important and unresolved challenge. Many different approaches have been proposed, most of which are surveyed in [2]. They include, among the others, distributed logic programming [3, 4], viral tuple-passing [5, 6], chemical-like reactions [7, 8, 9], abstract graph algorithms [10], spatial data streaming [11], and topological surgery [12], none of which has yet proven successful enough to be adopted into widespread use. One promising approach to the programming and control of such systems is to view the network of devices as a discrete approximation of the space through which they are distributed. The Proto spatial computing language [1] embraces this approach: a program is specified in terms of geometric computations and information flow on a continuous manifold1. These aggregate-level programs are automatically transformed into a set o...

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...lexity and dynamics of ICT systems [13], SAPERE brings the adoption of natural metaphors down to the core of its approach, by exploiting natureinspired mechanisms (and in particular bio-chemical ones =-=[14]-=-) for actually ruling the overall system dynamics. A. The Grounding Model SAPERE models a pervasive service environment as a spatial substrate, laid above the actual pervasive network infrastructure (...

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...ubstrate, SAPERE relies on a distributed implementation made up of a number of distributed engines allocated on the nodes of the infrastructure (see Figure 1), each realized as a reactive tuple space =-=[7]-=-, i.e., a tuple space with programmable pattern-marching mechanisms and supporting subscriptions to local events. Local application services on a node exploit such local engine for the support of thei...

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...over, these works focus on the construction of services using interacting agents, and the simulation is on a grid network, which does not map naturally (nor easily) to wireless networks. Mirko et al. =-=[17]-=- extends the tuple spaces by chemical-inspired (b) model to coordinate spatially pervasive services. Although the mechanism can effectively make services diffuse and interact in a spatial network, it ...

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...ervasive computing has already been studied and detailed in the series of works concerning the TOTA (Tuples On The Air) infrastructure [12], and recently in the context of chemical tuple spaces [17], =-=[18]-=- and pervasive service ecosystems [19], [21]. III. FRAMEWORK The framework presented here allows to model computational fields in pervasive and spatial systems via a specification language based on th...

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...plex challenges of these emerging environments. Recently, however, a unifying model based on computational fields has been identified as a generalization of a wide range of existing approaches (e.g., =-=[3, 19, 22, 25, 18, 21, 30, 22]-=-). Formalized as the computational field calculus [27], this universal language appears to provide a theoretical foundation on which effective general aggregate programming platforms can be built. Thi...

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...IMATE For this first exploration of predicting composition of distributed systems via stability theory, we choose to focus on one commonly used algorithm: distributed distance estimation. We have selected self-stabilizing distributed distance estimation algorithms as these are fairly well-studied building blocks used in many different applications—a few of the many examples include distance-vector routing (e.g., [8]), ad hoc networking (e.g., [9]), data collection in sensor networks (e.g., [10], biologically-inspired shape formation (e.g., [11], [12]), and chemical models of computation (e.g. [13]). More recently, it has been included in several efforts toward systematization of the design of resilient systems [1], [14], [15]. Surprisingly, however, even though there are known issues with convergence speed and instability that affect such algorithms, they do not appear to have previously been examined through the lens of stability theory. In this section, we thus present a simple implementation of self-stabilizing distances estimates and re-formalize it in terms of matrix algebra to facilitate the application of stability theory. A. Simple Distance Estimation Algorithm Here, we will co...

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... realised through the self-organising ecolaws that – by executing actions upon a small set of colocated LSAs – make global properties emerge. Eco-laws are structured as chemical-resembling rules [1], =-=[21]-=- of the kind “P+..+P --r--> Q+..+Q”. The semantics of an eco-law reaction is that of consuming reactant LSAs based on left-hand side patterns and producing a set of product LSAs based on the right-han...