Due to the dynamic and ephemeral nature of ubiquitous computing (ubicomp) environments, it is necessary that application software in ubicomp environments is situationaware (SA) and should be adaptable to both users' situation changes and the requirement changes. Reconfigurable Context-Sensitive Middleware (RCSM) has been developed to provide development and runtime support for SA software in ubicomp environments, but do not provide runtime support for on-demand context acquisition, action scheduling and dynamic reconfiguration of SA software, and development support that maximize the reusability. In this paper, the development and runtime support provided by RCSM have been substantially expanded to greatly simplify the development of situation-aware application software, and to achieve reusability and runtime reconfigurability simultaneously.

SUMMARYDue to the dynamic and ephemeral nature of ubiquitous computing (ubicomp) environments, it is especially important that the application software in ubicomp environments is trustworthy. In order to have trustworthy application software in ubicomp environments, situation-awareness (SAW) in the application software is needed to enforce flexible security policies and detect violations of security policies. In this paper, an approach is presented to provide development and runtime support to incorporate SAW in trustworthy ubicomp application software. The development support is to provide SAW requirement specification and automated code generation to achieve SAW in trustworthy ubicomp application software, and the runtime support is for context acquisition, situation analysis and situation-aware communication. To realize our approach, the improved Reconfigurable Context-Sensitive Middleware (RCSM) is developed to provide the above development and runtime support.

Service-based systems have many applications, including collaborative research and development, ebusiness, health care, environmental control, military applications, and homeland security. Service coordination is required for these systems to coordinate distributed activities. To achieve adaptive service coordination under changing environment and workload, situation-awareness is needed. In this paper, a model is presented for situationawareness (SAW) requirements in service-based systems. Based on this model, SAW agents are developed to incorporate situation-awareness and adaptive coordination in service-based systems.

Service-based systems have many applications, such as e-business, health care, and homeland security. In these systems, it is necessary to provide users the capability of composing services into workflows providing higher-level functionality. In dynamic service-oriented computing environments, it is desirable that service composition is automated and situation-aware to generate robust and adaptive workflows. In this paper, an automated situation-aware service composition approach is presented. This approach is based on the a-logic, a-calculus, and a declarative model for situation awareness (SAW). This approach consists of four major components: (1) analyzing SAW requirements using our SAW model, (2) translating our SAW model representation to a-logic specifications and specifying a control flow graph in a-logic as the service composition goal, (3) automated synthesis of a-calculus terms defining situation-aware workflow agents based on a-logic specifications for SAW requirements and the control flow graph, and (4) compilation of a-calculus terms to executable components.

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