Context Aware Session Management for Services in Ad Hoc Networks

The increasing ubiquity of wireless mobile devices is promoting unprecedented levels of electronic collaboration among devices interoperating to achieve a common goal. Issues related to host interoperability are addressed partially by the service-oriented computing paradigm. However, certain technical concerns relating to reliable interactions among hosts in ad hoc networks have not yet received much attention. We introduce ”follow-me sessions”, where interaction occur between a client and a service, rather than a specific provider or server. We allow the client to switch service providers if needed. The redundancy offers scope for reliable communication in the presence of mobility induced disconnections. We exploit strategies involving the use of contextual information, strong process migration, context-sensitive binding, and location-agnostic communication protocols. We show how follow-me sessions mitigate issues related to proxy-based service-oriented architectures in ad hoc networks, making them more reliable

Flexible provisioning of Web service workflows

Web services promise to revolutionise the way computational resources and business processes are offered and invoked in open, distributed systems, such as the Internet. These services are described using machine-readable meta-data, which enables consumer applications to automatically discover and provision suitable services for their workflows at run-time. However, current approaches have typically assumed service descriptions are accurate and deterministic, and so have neglected to account for the fact that services in these open systems are inherently unreliable and uncertain. Specifically, network failures, software bugs and competition for services may regularly lead to execution delays or even service failures. To address this problem, the process of provisioning services needs to be performed in a more flexible manner than has so far been considered, in order to proactively deal with failures and to recover workflows that have partially failed. To this end, we devise and present a heuristic strategy that varies the provisioning of services according to their predicted performance. Using simulation, we then benchmark our algorithm and show that it leads to a 700% improvement in average utility, while successfully completing up to eight times as many workflows as approaches that do not consider service failures

Planning strategically, designing architecturally : a framework for digital library services

In an era of unprecedented technological innovation and evolving user expectations and information seeking behaviour, we are arguably now an online society, with digital services increasingly common and increasingly preferred. As a trusted information provider, libraries are in an advantageous position to respond, but this requires integrated strategic and enterprise architecture planning, for information technology (IT) has evolved from a support role to a strategic role, providing the core management systems, communication networks, and delivery channels of the modern library. Further, IT components do not function in isolation from one another, but are interdependent elements of distributed and multidimensional systems encompassing people, processes, and technologies, which must consider social, economic, legal, organisational, and ergonomic requirements and relationships, as well as being logically sound from a technical perspective. Strategic planning provides direction, while enterprise architecture strategically aligns and holistically integrates business and information system architectures. While challenging, such integrated planning should be regarded as an opportunity for the library to evolve as an enterprise in the digital age, or at minimum, to simply keep pace with societal change and alternative service providers. Without strategy, a library risks being directed by outside forces with independent motivations and inadequate understanding of its broader societal role. Without enterprise architecture, it risks technological disparity, redundancy, and obsolescence. Adopting an interdisciplinary approach, this conceptual paper provides an integrated framework for strategic and architectural planning of digital library services. The concept of the library as an enterprise is also introduced

Unattended network operations technology assessment study. Technical support for defining advanced satellite systems concepts

The results are summarized of an unattended network operations technology assessment study for the Space Exploration Initiative (SEI). The scope of the work included: (1) identified possible enhancements due to the proposed Mars communications network; (2) identified network operations on Mars; (3) performed a technology assessment of possible supporting technologies based on current and future approaches to network operations; and (4) developed a plan for the testing and development of these technologies. The most important results obtained are as follows: (1) addition of a third Mars Relay Satellite (MRS) and MRS cross link capabilities will enhance the network's fault tolerance capabilities through improved connectivity; (2) network functions can be divided into the six basic ISO network functional groups; (3) distributed artificial intelligence technologies will augment more traditional network management technologies to form the technological infrastructure of a virtually unattended network; and (4) a great effort is required to bring the current network technology levels for manned space communications up to the level needed for an automated fault tolerance Mars communications network