Dazhi Huang

Toward Development of Adaptive Service-Based Software Systems

The rapid adoption of service-oriented architecture (SOA) in many large-scale distributed applications requires the development of adaptive service-based software systems (ASBS) with the capability of monitoring the changing system status, analyzing, and controlling tradeoffs among various quality-of-service (QoS) aspects, and adapting service configurations to satisfy multiple QoS requirements simultaneously. In this paper, our results toward the development of adaptive service-based software systems are presented. The formulation of activity-state-QoS (ASQ) models and how to use the data from controlled experiments to establish ASQ models for capturing the cause-effect dynamics among service activities, system resource states, and QoS in service-based systems are presented. Then, QoS monitoring modules based on ASQ models and SOA-compliant simulation models are developed to support the validation of the ASBS design. The main idea for developing QoS adaptation modules based on ASQ models is discussed. An experiment based on a voice communication service is used to illustrate our results.

Situation-aware personalized information retrieval for mobile Internet

Recent rapid advances in Internet-based information systems and handheld devices make it possible for users to retrieve information anytime and anywhere. Existing information retrieval (IR) techniques usually require the users to spend much effort to continuously refine their queries to obtain the results they want. Since each refinement is an interaction between a user and information systems, the larger the number of interactions, the more communication overhead and energy consumption are introduced. Due to the severe resource constraints of handheld devices, it is necessary to have an IR technique that can efficiently retrieve information for the user with only one or two interactions. In this paper, an efficient IR technique for mobile Internet by combining situation-based adaptation and profile-based personalization is presented.

Situation-aware contract specification language for middleware for ubiquitous computing

Ubicomp applications are characterized as situation-aware, frequently-and-ephemerally-communicated and QoS-properties-associated. Using middleware to provide multiple QoS support for these ubicomp applications will enhance the development of the ubicomp applications. To satisfy the different QoS requirements of various applications in ubicomp environments, which are heterogeneous and resource-variant, it is important for the underlining middleware to adapt to different QoS requirements and environments. Situation-Aware Contract Specification Language (SA-CSL) specifies the QoS requirements of the applications. The specification includes requirements in situation-awareness, real-time constraints and security properties. This specification is used to customize the middleware architecture to better satisfy these requirements. SA-CSL is based on the Separation of Concern (SoC) discipline used in the Aspect-Oriented Software Development (AOSD). It specifies the crosscutting aspects of situation-awareness, real-time constraints and security property separately. Because of the object-oriented design, SA-CSL is open for incorporating new QoS properties specification.

Support for situation awareness in trustworthy ubiquitous computing application software

Due 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. Copyright

Developing Service-Based Software Systems with QoS Monitoring and Adaptation

The rapid adoption of SOA in many large-scale distributed applications requires the development of adaptive service-based software systems (ASBS), which have the capability of monitoring the changing system status, analyzing and controlling tradeoffs among multiple QoS features, and adapting its service configuration to satisfy multiple QoS requirements simultaneously. In this paper, a performance-model-oriented approach to developing ASBS is presented. This approach consists of the establishment of performance models for SBS through controlled experiments, the development of QoS monitoring and adaptation (M/A) modules based on the performance models, and the validation of ASBS design through simulations. In our approach, four QoS features: timeliness, throughput, accuracy and security, which are important for many critical applications, are considered.

Adaptable situation-aware secure service-based (AS/sup 3/) systems

Service-oriented systems are distributed systems which have the major advantage of enabling rapid composition of distributed applications, regardless of the programming languages and platforms used in developing and running different components of the applications. In these systems, various capabilities are provided by different organizations as services interconnected by various types of networks. The services can be integrated following a specific workflow to achieve a mission goal for users. For large-scale service-based systems involving multiple organizations, high confidence and adaptability are of prime concern in order to ensure that users can use these systems anywhere, anytime with various devices, knowing that their confidentiality and privacy are well protected and the systems will adapt to satisfy their needs in various situations. Hence, these systems must be adaptable, situation-aware and secure. In this paper, an approach to rapid development of adaptable situation-aware secure service-based (AS/sup 3/) systems is presented. Our approach enables users to rapidly generate, discover, compose services into processes to achieve their goals based on the situation and adapt these processes when situation changes.

Situation-awareness for adaptive coordination in service-based systems

Service-based systems have many applications, including collaborative research and development, e-business, 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 situation-awareness (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.

Automated Situation-Aware Service Composition in Service-Oriented Computing

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.

Specification, decomposition and agent synthesis for situation-aware service-based systems

Service-based systems are distributed computing systems with the major advantage of enabling rapid composition of distributed applications, such as collaborative research and development, e-business, health care, military applications and homeland security, regardless of the programming languages and platforms used in developing and running various components of the applications. In dynamic service-oriented computing environment, situation awareness (SAW) is needed for system monitoring, adaptive service coordination and flexible security policy enforcement. To greatly reduce the development effort of SAW capability in service-based systems and effectively support runtime system adaptation, it is necessary to automate the development of reusable and autonomous software components, called SAW agents, for situation-aware service-based systems. In this paper, a logic-based approach to declaratively specifying SAW requirements, decomposing SAW specifications for efficient distributed situation analysis, and automated synthesis of SAW agents is presented. This approach is based on AS^3 calculus and logic, and our declarative model for SAW. Evaluation results of our approach are also presented.

A Software Cybernetics Approach to Deploying and Scheduling

Service-based systems (SBS) are being adopted by many distributed systems. Applications in SBS can often be viewed as the composition of various computing services following specific workflows. These workflows often need to satisfy various timing and resource constraints. In this paper, a software cybernetics approach to deploying and scheduling workflows with timing and resource constraints in SBS is presented. In our approach, a logic-based technique for modeling and solving timing and resource constraints for workflows in SBS is developed to generate the initial resource assignments, schedules and deployment plans of agents for workflows. The principles and concepts in software cybernetics are applied to guide the synthesis of software controllers for monitoring and adapting system behavior