3 research outputs found
Supporting Management lnteraction and Composition of Self-Managed Cells
Management in ubiquitous systems cannot rely on human intervention or centralised
decision-making functions because systems are complex and devices
are inherently mobile and cannot refer to centralised management applications
for reconfiguration and adaptation directives. Management must be devolved,
based on local decision-making and feedback control-loops embedded in autonomous
components. Previous work has introduced a Self-Managed Cell (SMC)
as an infrastructure for building ubiquitous applications. An SMC consists
of a set of hardware and software components that implement a policy-driven
feedback control-loop. This allows SMCs to adapt continually to changes in
their environment or in their usage requirements. Typical applications include
body-area networks for healthcare monitoring, and communities of unmanned
autonomous vehicles (UAVs) for surveillance and reconnaissance operations.
Ubiquitous applications are typically formed from multiple interacting autonomous
components, which establish peer-to-peer collaborations, federate and
compose into larger structures. Components must interact to distribute management
tasks and to enforce communication strategies. This thesis presents
an integrated framework which supports the design and the rapid establishment
of policy-based SMC interactions by systematically composing simpler abstractions
as building elements of a more complex collaboration. Policy-based
interactions are realised – subject to an extensible set of security functions –
through the exchanges of interfaces, policies and events, and our framework
was designed to support the specification, instantiation and reuse of patterns of
interaction that prescribe the manner in which these exchanges are achieved.
We have defined a library of patterns that provide reusable abstractions for
the structure, task-allocation and communication aspects of an interaction,
which can be individually combined for building larger policy-based systems in
a methodical manner. We have specified a formal model to ensure the rigorous
verification of SMC interactions before policies are deployed in physical devices.
A prototype has been implemented that demonstrates the practical feasibility
of our framework in constrained resources
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Requirements-Driven Adaptation of Choreographed Interactions
Electronic services are emerging as the de-facto enabler of interaction interoperability across organization boundaries. Cross-organizational interactions are often “choreographed”, i.e. specified by a messaging protocol from a global point of view independent of the local view of each interacting organization. Local requirements motivating an interaction as well as the global contextual requirements governing the interaction inevitably evolve over time, requiring adaptation of the corresponding interaction protocol. Adaptation of an interaction protocol must ensure the satisfaction of both sets of interaction requirements while maintaining consistency between the global view and the local views of an interaction specification. Such adaptation is not possible with the current state-of-the-art representations of choreographed interactions, as they capture only operational messaging specifications detached from both local organizational requirements as well as global contextual requirements.
This thesis presents three novel contributions that tackle adaptation of choreographed interaction protocols: an automated technique for deriving an interaction protocol from requirements, a formalization of consistency between local and global views, and a framework for guiding the adaptation of a choreographed interaction. A choreographed interaction is specified using models of organizational requirements motivating the interaction. We employ the formal semantics embedded in requirements models to automatically derive an interaction protocol. We propose a framework for relating the global and local views of interaction specification and maintaining consistency between them. We develop a metamodel for interaction specification, from which we enumerate adaptation operations. We build a catalogue that provides guidance on performing each operation and propagating changes between the global and local views. These contributions are evaluated using examples from the literature as well as a real-world case study
A Compositional Approach to Connector Construction
We develop a notion of higher-order connector towards supporting the systematic construction of architectural connectors for software design. The idea i