PoK

Authors: Gian Pietro Picco, Amy L. Murphy, Gruia-Catalin Roman

Description:
Mobility poses peculiar challenges that must be addressed by novel programming constructs. LIME (Linda in a Mobile Environment) tackles the problem by adopting a coordination perspective inspired by work on the Linda model. The context for computation, represented in Linda by a single, globally accessible, persistent tuple space, is reinterpreted in LIME as the transient sharing of the tuple spaces carried by individual mobile units. Additional constructs provide increased expressiveness, by enabling programs to deal with the location of tuples and to react to specied states. The resulting model provides a minimalist set of abstractions that promise to facilitate rapid and dependable development of mobile applications. In this paper, we illustrate the model underlying LIME, present the programming interface of the companion middleware, and discuss how applications and higher-level middleware services can be built using it.

Authors: Qingfeng Huang, Chenyang Lu, Gruia-Catalin Roman

Description:
This paper is concerned with coordinated delivery of messages in sensor networks. The notion of multicast is re-examined in light of a new set of requirements that are speci?c to such networks. The result of this investigation is a new concept called mobicast. It entails the delivery of messages to large sets of nodes in a manner that satis ?es a potentially dynamic set of spatiotemporal constraints. In order to demonstrate the feasibility of mobicast, we present a novel topologyaware protocol for sensor networks. Worst-case analysis shows that the protocol provides strong spatial and temporal delivery guarantees under a set of reasonable assumptions about the network. The design of the protocol relies on new notions of compactness for spatially distributed networks. By explicitly addressing the temporal domain associated with message delivery, mobicast is more general than geocast and makes it possible to save precious resources in sensor networks by exploiting its inherent just-in-time delivery semantics.

Authors: Gruia-Catalin Roman, Christine Julien, Jamie Payton

Description:
Context-aware computing refers to a computing paradigm in which the behavior of individual components is determined by the circumstances in which they find themselves to an extent that greatly exceeds the typical system/environment interaction pattern common to most modern computing. The environment has an exceedingly powerful impact on a particular application component either because the latter needs to adapt in response to changing external conditions or because it relies on resources whose availability is subject to continuous change. In this paper we seek to develop a systematic understanding of the quintessential nature of context-aware computing by constructing a formal model and notation for expressing context-aware computations. We start with the basic premise that, in its most extreme form, context should be made manifest in a manner that is highly local in appearance and decoupled in fact. Furthermore, we assume a notion of context that is relative to the needs of each individual component, and we xpect context-awareness to be maintained in a totally transparent manner with minimal programming eort. We construct the model from first principles, seek to root our decisions in these formative assumptions, and make every effort to preserve minimality of concepts and elegance of notation.

Authors: Rohan Sen, Radu Handorean, Gruia-Catalin Roman, Christopher Gill

Description:
We began this chapter by introducing the notion of service oriented computing and its applicability in ad hoc wireless networks. We discussed existing service oriented computing models and highlighted the Semantic Web as an example of service oriented computing at work. We then discussed issues of service oriented computing in ad hoc wireless networks as they pertain to each of the salient elements of a service oriented computing framework, viz. description, advertisement, discovery, invocation and composition. For each of these elements, we distilled a set of imperatives for the ad hoc wireless setting. Finally, we highlighted some key research issues and enhancements which we see as defining the next steps for research in this area. We hope this chapter has given a perspective on the issues, challenges and imperatives of designing and implementing a service oriented computing framework for ad hoc wireless settings, one that will serve as a guide for future research.

Authors: Radu Handorean, Christopher Gill, Gruia-Catalin Roman

Description:
Much of the work on networking and communications is based on the premise that components interact in one of two ways: either they are connected via a stable wired or wireless network, or they make use of persistent storage repositories accessible to the communicating parties. A new generation of networks raises serious questions about the validity of these fundamental assumptions. In mobile ad hoc wireless networks connections are transient and availability of persistent storage is rare. This paper is concerned with achieving communication among mobile devices that may never find themselves in direct or indirect contact with each other at any point in time. A unique feature of our contribution is the idea of exploiting information associated with the motion and availability profiles of the devices making up the ad hoc network. This is the starting point for an investigation into a range of possible solutions whose essential features are controlled by the manner in which motion profiles are acquired and the extent to which such knowledge is available across an ad hoc network.