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ABSTRACT: There have been works considering protocols for accessing partitioned data. Most of these works assume the local cluster based environment and their designs target atomic semantics. However, when considering widely distributed cloud storage systems, these existing protocols may not scale well. In this paper, we analyze the requirements of access protocols for storage systems based on data partitioning schemes in widely distributed cloud environments. We consider the regular semantics instead of atomic semantics to improve access efficiency. Then, we develop an access protocol following the requirements to achieve correct and efficient data accesses. Various protocols are compared experimentally and the results show that our protocol yields much better performance than the existing ones.
Reliable Distributed Systems, 2010 29th IEEE Symposium on; 12/2010
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ABSTRACT: In cloud computing, data, software, and hardware are wrapped as services, which are made available on demand. Given a demand, the associated services need to interact with each other to fulfill the task. As a result, service reuse and composition are inevitable. The current prevailing Web service composition paradigms follow the bottom-up manner, i.e., the concrete services are physically constructed first. Then, some mechanisms are applied to raise the level of abstraction so that the service composition process can be performed at a higher level. However, such paradigms are very fragile. In the event that some semantic contents are missing, the composition will fail even though the majority of services may be available. In this paper, we present a service composition approach that is a combination of the bottom-up and top-down strategies. In terms of bottom-up, our approach follows the current service composition methods and tries to use existing Web services to meet the given demand. If the composition process fails, virtual services are proposed by the composer to bridge the semantic gap so that the composition process will continue. Virtual services may not have physical counterparts and may exist only conceptually. However, it provides a high-level specification for a service that is missing. This is a typical top-down manner, i.e., by following the specification, developers and designers will have clear ideas regarding what to develop to meet the given demand. Therefore, our approach can further improve the level of service reuse.
Semantic Computing (ICSC), 2010 IEEE Fourth International Conference on; 10/2010
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ABSTRACT: Cyber-Physical Systems (CPSs) are combinations of physical entities controlled by software systems to accomplish specified tasks under stringent real-time and physical entity constraints. As more and more physical entities are equipped with embedded computers, they are becoming more and more intelligent. However, the problem of effectively composing the services provided by cyber and physical entities to achieve specific goals still remains a challenge. Traditional service-oriented models and composition techniques are insufficient for CPS. In this paper, we present a novel Physical-Entity (PE) service-oriented model to address the problem, including the concepts of PE-ontology and PE-SOA specifications. Based on the model, we develop a two-level compositional reasoning approach, which divides the process into abstract and physical levels to expedite the composition process. With the assistance of the PE-ontology and PE-SOA, abstract level reasoning is performed by hiding the physical level details. This separation greatly reduces the search space for both levels through a divide-and-conquer technique. The model and the composition approach are illustrated using a simplified emergency response case study system.
Service-Oriented Computing and Applications (SOCA), 2009 IEEE International Conference on; 02/2009
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ABSTRACT: We present a fast iterative planner (FIP) that aims to handle planning problems involving nondeterministic actions. In contrast to existing iterative planners, FIP is built upon Graphplan's intrinsic features, thus, enabling Graphplan variants, including SGP and FF, to be enhanced with the capability of iterative planning. In addition, FIP is able to produce program-like plans with conditional and loop constructs, and achieves efficient planning via novel algorithms for manipulating planning graphs. Experimental results on several nondeterministic planning problems show that FIP is more efficient than the well-known planner, MBP, especially as the size of the problems increases.
Tools with Artificial Intelligence, 2008. ICTAI '08. 20th IEEE International Conference on; 12/2008
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ABSTRACT: Space-division multiple access (SDMA) protocols provide a bounded delay communication medium that is collision free. In these protocols, there is one-to-one mapping between a specific location on the road to a bandwidth division (i.e. a specific timeslot). An implicit assumption is that there is no interference among vehicles traveling on different roads that could be within the sensing range of each other. Although this assumption is generally valid for highway scenarios, it does not always hold for urban road scenarios such as intersecting roads. Message losses due to packet collisions can take place near intersections when vehicles from different approaching roads attempt to transmit at the same time. Hence, in this paper, we address the extension of SDMA protocols for intersecting roads. We present and compare two algorithms for this problem based on a set of evaluation criteria for real-time car-to-car communication systems.
ITS Telecommunications, 2008. ITST 2008. 8th International Conference on; 11/2008
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ABSTRACT: Software architectures have emerged as a promising approach for managing, analyzing, building, integrating, reusing, and improving the quality of software systems. Specifically, early design decisions can be improved by the analysis of architectural models for different properties. This paper addresses the problem of estimating the reliability of data-flow architectures before the construction of the system. The proposed model uses an operational profile of the system and a set of component test profiles. A test profile is a set of test cases extended with information about the software intra-component execution. The analysis of the system is performed by composing the test points along the virtual execution among the components. This strategy overcomes the determination of intermediate operational profiles. In addition, metrics to select the best match in the execution trace and to evaluate the selection error in such kind of match are described.
Computer Science, 2008. ENC '08. Mexican International Conference on; 11/2008
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ABSTRACT: High assurance systems have evolving requirements and, hence, the definition for assurance requirements should allow evolution. We recommend the use of ontology to capture such evolving requirements. In this paper, we introduce the concept of trustworthiness to include dependability and some additional high assurance attributes. We develop an ontology of trustworthiness aspects and an ontology of system entities. Based on these ontologies, a framework for trustworthiness assessment is constructed. This framework supports systematic and well guided trustworthy assessment from the individual system entities to the overall integrated system. It also offers the potential for automated trustworthiness assessment.
Semantic Computing, 2008 IEEE International Conference on; 09/2008
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ABSTRACT: Service oriented architecture (SOA) has become a popular paradigm for software development in many application domains, including real-time applications. Timing analysis is a critical issue which can guide service composition to best satisfy the real time requirements of the composed system. However, existing timing analysis works do not sufficiently address some important issues. For example, admission control is an important technique for real time assurance, but most of the timing analysis techniques do not take admission control into account and, hence, may result in unrealizable decisions. Also, communication time is an important factor in real-time assurance, but most of the works do not provide clear approaches in dealing with communication time analysis. In this paper, we propose a timing specification model and analysis techniques for real-time service-oriented systems. In the specification model, a thorough consideration of all information required for timing analysis is discussed. For timing analysis, we consider the service time softly guaranteed by the admission control policy as well as estimated communication cost to reach more accurate timing estimates. Also, to avoid the analysis overhead in large-scale SOA systems, we propose a three-phase approach. In this approach, we first use a highly efficient but moderately accurate algorithm to eliminate most of the candidate compositions. More accurate timing prediction is performed on a small number of selected compositions in the second phase. In the third phase, specific concrete services are selected and admissions are performed to finalize the composition and service grounding. The approach is scalable and can effectively achieve service composition for real time requirement satisfaction.
Computer Software and Applications, 2008. COMPSAC '08. 32nd Annual IEEE International; 09/2008
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ABSTRACT: In transportation systems, the existing infrastructure can potentially be used more efficiently by deploying intelligent net-centric solutions that coordinate vehicles and traffic signals in real-time. For capacity planning and assessing the cost/benefit tradeoffs of intelligent net-centric coordination infrastructures, it is essential to determine the performance of optimal solutions, i.e., the best possible traffic flow that can be achieved. Given the scale and complexity of transportation systems, it may not be feasible to actually achieve these optimal performances in practice. However, if the results show that substantial improvements are possible by simply using the current physical roadway infrastructures more effectively, then one can justify the cost of deploying intelligent vehicle/traffic-light coordination systems. In this paper, we demonstrate these concepts through a case study of scheduling vehicles on a grid of intersecting roads. We develop heuristic algorithms and an optimization model using the space-time network for this problem, and compare them. Moreover, we also compare the space-time network modeling technique with the integer programming optimization approach and show that the former is better for modeling traffic coordination systems.
Sensor Networks, Ubiquitous and Trustworthy Computing, 2008. SUTC '08. IEEE International Conference on; 07/2008
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ABSTRACT: Content adaptation is an important technique for mobile devices. Existing content adaptation systems have been developed with specific adaptation goals. In this paper, we present an extensible content adaptation system, Xadaptor. We take a rule-based approach to facilitate extensible, systematic, and adaptive content adaptation. It integrates adaptation mechanisms for various content types and organizes them into the rule base. Rules are invoked based on the individual client information. We classify HTML page objects into structure, content, and pointer objects. Existing content adaptation techniques mainly focus on content objects and do not consider adaptation for structure and pointer objects. In Xadaptor, novel adaptation techniques for the structure object HTML table have been developed. We use fuzzy logic to model the adaptation quality and guide the adaptation decision. To demonstrate the feasibility of our approach, we have implemented a prototype system. Experimental studies show that Xadaptor is capable of on-the-fly content adaptation and is easily extensible
IEEE Transactions on Knowledge and Data Engineering 02/2007; 19(1):127-140. · 1.66 Impact Factor
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ABSTRACT: Automated code synthesis is a constructive process that can be used to generate programs from specifications. It can, thus, greatly reduce the software development cost and time. The use of formal code synthesis approach for software generation further increases the dependability of the system. Though code synthesis has many potential benefits, the synthesis techniques are still limited. Meanwhile, components are widely used in embedded system development. Applying code synthesis to component based software development (CBSD) process can greatly enhance the capability of code synthesis while reducing the component composition efforts. In this paper, we discuss the issues and techniques for applying deductive code synthesis techniques to CBSD. For deductive synthesis in CBSD, a rule base is the key for inferring appropriate component composition. We use the code patterns to guide the development of rules. Code patterns have been proposed to capture the typical usages of the components. Several general composition operations have been identified to facilitate systematic composition. We present the technique for rule development and automated generation of new patterns from existing code patterns. A case study of using this method in building a real-time control system is also presented.
Object and Component-Oriented Real-Time Distributed Computing, 2006. ISORC 2006. Ninth IEEE International Symposium on; 02/2006
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Wei Hao,
Jicheng Fu,
Jiang He,
I-Ling Yen,
Farokh Bastani,
Ing-Ray Chen,
J Fu,
J He,
I Yen, F Bastani,
I.-R Chen
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ABSTRACT: Proxy caching is an effective approach to reduce the response latency to client requests, web server load, and network traffic. Recently there has been a major shift in the usage of the Web. Emerging web applications require increasing amount of server-side processing. Current proxy protocols do not support caching and execution of web processing units. In this paper, we present a weblet environment, in which, processing units on web servers are implemented as weblets. These weblets can migrate from web servers to proxy servers to perform required computation and provide faster responses. Weblet engine is developed to provide the execution environment on proxy servers as well as web servers to facilitate uniform weblet execution. We have conducted thorough experimental studies to investigate the performance of the weblet approach. We modify the industrial standard e-commerce benchmark TPC-W to fit the weblet model and use its workload model for performance comparisons. The experimental results show that the weblet environment significantly improves system performance in terms of client response latency, web server throughput, and workload. Our prototype weblet system also demonstrates the feasibility of integrating weblet environment with current web/proxy infrastructure.
World Wide Web. 01/2006; 9:253-275.
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ABSTRACT: To better protect information systems, computation time data protection needs to be considered such that even when the system is partially compromised, the security of the system is still assured. Secure multiparty computation approaches provides a possible solution for computation time data protection, but are too costly (in communication) to be practical. In this paper, we design an adaptive multi-level secure computation algorithm with the goals of reducing the average communication overheads. The adaptive algorithm runs a less secure protocol to reduce the communication overhead when there is no threat. The system adapts to a more secure but less efficient protocol when security threat is detected. Thus, the system yields better performance at normal execution time while still assures security protection at the presence of security threats.
Parallel and Distributed Systems, 2005. Proceedings. 11th International Conference on; 08/2005
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ABSTRACT: Web services have gained high popularity in the development of distributed application systems. Some critical applications also consider using web services paradigm due to the benefits of interoperability, reusability, and adaptability. To support critical applications, existing web service model needs to be extended to assure survivability. In this paper, we introduce the design of a novel survivable Web service (SWS) framework that supports continuous operation even in the presence of failures and security attacks. The replication scheme and N-Modular Redundancy (NMR) concept are used as the basis for achieving survivability. Due to replication, communication among multiple web services becomes costly. We develop protocols, including the Inter-Group Communication (SWS-IGC) and Message Ordering (SWS-MO) protocols, to guarantee efficient and correct communication. Preliminary performance studies show that the SWS framework only incurs a moderate overhead due to the incorporation of survivability assurance.
Parallel and Distributed Processing Symposium, 2005. Proceedings. 19th IEEE International; 05/2005
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ABSTRACT: Component-based development (CBD) techniques have been widely used to enhance the productivity and reduce the cost for software systems development. However, applying CBD techniques to embedded software development faces additional challenges. For embedded systems, it is crucial to consider the quality of service (QoS) attributes, such as timeliness, memory limitations, output precision, battery constraints. Frequently, multiple components implementing the same functionality with different QoS properties can be used to compose a system. Also, software components may have parameters that can be configured to satisfy different QoS requirements. Composition analysis, which is used to determine the most suitable component selections and parameter settings to best satisfy the system QoS requirement, is very important in embedded software development process. In this paper, we present a model and the methodologies to facilitate composition analysis. We define QoS requirements as constraints and objectives. Composition analysis is performed based on the QoS properties and requirements to find solutions (component selections and parameter settings) that can optimize the QoS objectives while satisfying the QoS constraints. We use a multiobjective concept to model the composition analysis problem and use an evolutionary algorithm to determine the Pareto-optimal solutions efficiently.
Real Time and Embedded Technology and Applications Symposium, 2005. RTAS 2005. 11th IEEE; 04/2005
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ABSTRACT: With the rapid growth in the development of modern and sophisticated software applications, such as multimodal distributed systems, the complexity of software development processes has increased enormously, posing an urgent need for automation of some of these processes. One of the key software development process is system testing. In This work, we evaluate the potential application of AI planning techniques in automating the testing process. We propose a framework for an automated planning system (APS) for applying AI planning techniques for automated testing of a software module. Using a comprehensive example, we demonstrate how the MEA-Graphplan (means-ends analysis graphplan) algorithm can be used to automatically generate test data (sequence of steps or actions) to transform the system from the current state to some desired goal state. MEA-Graph planning might prove to be computationally more efficient and effective than basic graph planning technique because here the planning graph is expanded in a goal-oriented manner using regression-matching graph constructed by regressing goals over actions that can overcome the problem of state-space explosion during graph expansion phase of the planning.
Tools with Artificial Intelligence, 2004. ICTAI 2004. 16th IEEE International Conference on; 12/2004
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ABSTRACT: The training time for SVMs to compute the maximal marginal hyper-plane is at least O(N<sup>2</sup>) with the data set size N, which makes it nonfavorable for large data sets. This work presents a study for enhancing the training time of SVMs, specifically when dealing with large data sets, using hierarchical clustering analysis. We use the dynamically growing self-organizing tree (DGSOT) algorithm for clustering because it has proved to overcome the drawbacks of traditional hierarchical clustering algorithms. Clustering analysis helps find the boundary points, which are the most qualified data points to train SVMs, between two classes. We present a new approach of combination of SVMs and DGSOT, which starts with an initial training set and expands it gradually using the clustering structure produced by the DGSOT algorithm. We compare our approach with the Rocchio Bundling technique in terms of accuracy loss and training time gain using two benchmark real data sets.
Tools with Artificial Intelligence, 2004. ICTAI 2004. 16th IEEE International Conference on; 12/2004
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ABSTRACT: Summary form only given. Due to the extensive use of computers and networks in critical systems, survivability is no longer a luxury but an essential requirement. We consider survivability assurance for critical applications where the system may incur accidental failures as well as intentional attacks. A successful attack can penetrate and compromise a pan of the system and, consequently, make the system behave like incurring a malicious failure. We model successful attacks as Byzantine failures and use the replication scheme to uniformly cope with failures and attacks. Instead of using conventional replication protocols that generally have a high overhead, we develop a novel coordination protocol, namely, adaptive NMR (ANMR) algorithm, to provide efficient coordination among replicated sites. Also, a special data partitioning technique is used with ANMR to assure confidentiality of the system even if it is partially compromised. Due to the adaptive nature, our ANMR algorithm reduces the communication overhead incurred in conventional NMR schemes. When there is no failure, the system operates at a very good performance. When failures occur, the system adapts to the NMR scheme gracefully.
Parallel and Distributed Processing Symposium, 2004. Proceedings. 18th International; 05/2004
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ABSTRACT: To better protect information systems, computation time data protection needs to be considered such that even when the system is partially compromised, the security of the system can still be assured. All existing approaches incur high overhead. Some do not support full computation power. In this paper, we propose a secure computation algorithm with the goals of reducing the communication overhead and providing full computation power. We reduce the communication overhead by aggregating multiple operations. Our algorithm has full computation power, and yields better performance than existing approaches. The proposed algorithm focuses on confidentiality assurance. Replication schemes can be combined with the algorithm to assure system integrity.
High Assurance Systems Engineering, 2004. Proceedings. Eighth IEEE International Symposium on; 04/2004
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ABSTRACT: The rapid growth in the demand of embedded systems and the
increased complexity of embedded software pose an urgent need for
advanced embedded software development techniques. Software technology
is shifting toward semi-automated code generation and integration of
systems from components. Component-based development (CBD) techniques
can significantly reduce the time and cost for developing software
systems. However, there are some difficult problems with the CBD
approach. Component identification and retrieval as well as component
composition require extensive knowledge of the components. Designers
need to go through a steep learning curve in order to effectively
compose a system out of available components. We discuss an integrated
mechanism for component-based development of embedded software. We
develop an On-line Repository for Embedded Software (ORES) to facilitate
component management and retrieval. ORES uses an ontology-based approach
to facilitate repository browsing and effective search. Based on ORES,
we develop the code template approach to facilitate semi-automated
component composition. A code template can be instantiated by different
sets of components and, thus, offers more flexibility and
configurability and better reuse. Another important aspect in embedded
software is the nonfunctional requirements and properties. In ORES, we
capture nonfunctional properties of components and provide facilities
for the analysis of overall system properties
Object-Oriented Real-Time Distributed Computing, 2002. (ISORC 2002). Proceedings. Fifth IEEE International Symposium on; 02/2002
