The development of new Web services through the composition of existing ones has gained a conside... more The development of new Web services through the composition of existing ones has gained a considerable momentum as a means to realise business-to-business collaborations. Unfortunately, given that services are often developed in an ad hoc fashion using manifold technologies and standards, connecting and coordinating them in order to build composite services is a delicate and time-consuming task. In this paper, we describe the design and implementation of a system in which services are composed using a model-driven approach, and the resulting composite services are orchestrated following a peer-to-peer paradigm. The system provides tools for specifying composite services through statecharts, data conversion rules, and multi-attribute provider selection policies. These specifications are interpreted by software components that interact in a peer-to-peer way to coordinate the execution of the composite service. We report results of an experimental evaluation showing the relative advantages of this peer-to-peer approach with respect to a centralised one.
The optimized distance-based access methods currently available for multidimensional indexing in ... more The optimized distance-based access methods currently available for multidimensional indexing in multimedia databases have been developed based on two major assumptions: a suitable distance function is known a priori and the dimensionality of the image features is low. It is not trivial to define a distance function that best mimics human visual perception regarding image similarity measurements. Reducing high-dimensional features in images using the popular principle component analysis (PCA) might not always be possible due to the non-linear correlations that may be present in the feature vectors. We propose in this paper a fast and robust hybrid method for non-linear dimensions reduction of composite image features for indexing in large image database. This method incorporates both the PCA and non-linear neural network techniques to reduce the dimensions of feature vectors so that an optimized access method can be applied. To incorporate human visual perception into our system, we also conducted experiments that involved a number of subjects classifying images into different classes for neural network training. We demonstrate that not only can our neural network system reduce the dimensions of the feature vectors, but that the reduced dimensional feature vectors can also be mapped to an optimized access method for fast and accurate indexing.
We present a framework for Web services provisioning in a hybrid environment of fixed and mobile ... more We present a framework for Web services provisioning in a hybrid environment of fixed and mobile computing resources. Several obstacles still hinder the seamless provisioning of Web services in mobile environments. Examples of such obstacles are: throughput and connectivity of wireless networks, limited computing resources of mobile devices, and risks of communication channel disconnections. In the proposed framework, software agents represent users, providers of services, and providers of resources. The business logic of composite services is expressed as a process model using statecharts formalism. Among other things, the use of agents provides an infrastructure that has the ability to handle disconnections during service preparation for execution. The framework also integrates a service execution planning approach to optimally select computing resources (fixed or mobile) on top of which services will be executed.
This paper discusses how communities of Web services sustain the high availability of Web service... more This paper discusses how communities of Web services sustain the high availability of Web services engaged in composition scenarios. Availability is the proportion of time that a system is in a functioning condition. Web services offering the same functionality like HotelBooking are gathered into a single community regardless of who developed them, where they are located, and how they function. The current practice to achieve Web services high-availability advocates the use of replicas, which are managed according to specific replication strategies and come into play when the original Web service to back-up fails. Replacing Web services replicas with similarly functional Web services offers solutions to some of the limitations that feature these strategies, but at the same time raises other issues that are examined in this paper.
The development of new services through the integration of existing ones has gained a considerabl... more The development of new services through the integration of existing ones has gained a considerable momentum as a means to create and streamline business-to-business collaborations. Unfortunately, as Web services are often autonomous and heterogeneous entities, connecting and coordinating them in order to build integrated services is a delicate and time-consuming task. In this paper, we describe the design and implementation of a system through which existing Web services can be declaratively composed, and the resulting composite services can be executed following a peer-to-peer paradigm, within a dynamic environment. This system provides tools for specifying composite services through. statecharts, data conversion rules, and provider selection, policies. These specifications are then translated into XML documents that can be interpreted by peer-to-peer inter-connected software components, in order to provision the composite service without requiring a central authority
The development of new Web services through the composition of existing ones has gained a conside... more The development of new Web services through the composition of existing ones has gained a considerable momentum as a means to realise business-to-business collaborations. Unfortunately, given that services are often developed in an ad hoc fashion using manifold technologies and standards, connecting and coordinating them in order to build composite services is a delicate and time-consuming task. In this paper, we describe the design and implementation of a system in which services are composed using a model-driven approach, and the resulting composite services are orchestrated following a peer-to-peer paradigm. The system provides tools for specifying composite services through statecharts, data conversion rules, and multi-attribute provider selection policies. These specifications are interpreted by software components that interact in a peer-to-peer way to coordinate the execution of the composite service. We report results of an experimental evaluation showing the relative advantages of this peer-to-peer approach with respect to a centralised one.
The optimized distance-based access methods currently available for multidimensional indexing in ... more The optimized distance-based access methods currently available for multidimensional indexing in multimedia databases have been developed based on two major assumptions: a suitable distance function is known a priori and the dimensionality of the image features is low. It is not trivial to define a distance function that best mimics human visual perception regarding image similarity measurements. Reducing high-dimensional features in images using the popular principle component analysis (PCA) might not always be possible due to the non-linear correlations that may be present in the feature vectors. We propose in this paper a fast and robust hybrid method for non-linear dimensions reduction of composite image features for indexing in large image database. This method incorporates both the PCA and non-linear neural network techniques to reduce the dimensions of feature vectors so that an optimized access method can be applied. To incorporate human visual perception into our system, we also conducted experiments that involved a number of subjects classifying images into different classes for neural network training. We demonstrate that not only can our neural network system reduce the dimensions of the feature vectors, but that the reduced dimensional feature vectors can also be mapped to an optimized access method for fast and accurate indexing.
We present a framework for Web services provisioning in a hybrid environment of fixed and mobile ... more We present a framework for Web services provisioning in a hybrid environment of fixed and mobile computing resources. Several obstacles still hinder the seamless provisioning of Web services in mobile environments. Examples of such obstacles are: throughput and connectivity of wireless networks, limited computing resources of mobile devices, and risks of communication channel disconnections. In the proposed framework, software agents represent users, providers of services, and providers of resources. The business logic of composite services is expressed as a process model using statecharts formalism. Among other things, the use of agents provides an infrastructure that has the ability to handle disconnections during service preparation for execution. The framework also integrates a service execution planning approach to optimally select computing resources (fixed or mobile) on top of which services will be executed.
This paper discusses how communities of Web services sustain the high availability of Web service... more This paper discusses how communities of Web services sustain the high availability of Web services engaged in composition scenarios. Availability is the proportion of time that a system is in a functioning condition. Web services offering the same functionality like HotelBooking are gathered into a single community regardless of who developed them, where they are located, and how they function. The current practice to achieve Web services high-availability advocates the use of replicas, which are managed according to specific replication strategies and come into play when the original Web service to back-up fails. Replacing Web services replicas with similarly functional Web services offers solutions to some of the limitations that feature these strategies, but at the same time raises other issues that are examined in this paper.
The development of new services through the integration of existing ones has gained a considerabl... more The development of new services through the integration of existing ones has gained a considerable momentum as a means to create and streamline business-to-business collaborations. Unfortunately, as Web services are often autonomous and heterogeneous entities, connecting and coordinating them in order to build integrated services is a delicate and time-consuming task. In this paper, we describe the design and implementation of a system through which existing Web services can be declaratively composed, and the resulting composite services can be executed following a peer-to-peer paradigm, within a dynamic environment. This system provides tools for specifying composite services through. statecharts, data conversion rules, and provider selection, policies. These specifications are then translated into XML documents that can be interpreted by peer-to-peer inter-connected software components, in order to provision the composite service without requiring a central authority
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Papers by Michael Sheng