Context Aware Service Oriented Computing in Mobile Ad Hoc Networks

These days we witness a major shift towards small, mobile devices, capable of wireless communication. Their communication capabilities enable them to form mobile ad hoc networks and share resources and capabilities. Service Oriented Computing (SOC) is a new emerging paradigm for distributed computing that has evolved from object-oriented and component-oriented computing to enable applications distributed within and across organizational boundaries. Services are autonomous computational elements that can be described, published, discovered, and orchestrated for the purpose of developing applications. The application of the SOC model to mobile devices provides a loosely coupled model for distributed processing in a resource-poor and highly dynamic environment. Cooperation in a mobile ad hoc environment depends on the fundamental capability of hosts to communicate with each other. Peer-to-peer interactions among hosts within communication range allow such interactions but limit the scope of interactions to a local region. Routing algorithms for mobile ad hoc networks extend the scope of interactions to cover all hosts transitively connected over multi-hop routes. Additional contextual information, e.g., knowledge about the movement of hosts in physical space, can help extend the boundaries of interactions beyond the limits of an island of connectivity. To help separate concerns specific to different layers, a coordination model between the routing layer and the SOC layer provides abstractions that mask the details characteristic to the network layer from the distributed computing semantics above. This thesis explores some of the opportunities and challenges raised by applying the SOC paradigm to mobile computing in ad hoc networks. It investigates the implications of disconnections on service advertising and discovery mechanisms. It addresses issues related to code migration in addition to physical host movement. It also investigates some of the security concerns in ad hoc networking service provision. It presents a novel routing algorithm for mobile ad hoc networks and a novel coordination model that addresses space and time explicitly

Enhancing Adaptivity via Standard Dynamic Scheduling Middleware

This paper makes three contributions to research on QoS-enabled middleware for open distributed real-time embedded (DRE) systems. First, it describes the design and implementation of a dynamic scheduling framework based on the OMG Real-Time CORBA 1.2 specification (RTC1.2) that provides capabilities for (1) propagating QoS parameters and a locus of execution across endsystems via a distributable thread abstraction and (2) enforcing the scheduling of multiple distributable threads dynamically using standard CORBA middleware. Second, it examines the results of empirical studies that show how adaptive dynamic scheduling and management of distributable threads can be enforced efficiently in standard middleware for open DRE systems. Third, it presents results from case studies of multiple adaptive middleware QoS management technologies to monitor and control the quality, timeliness, and criticality of key operations adaptively in a representative DRE avionics system