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Web services promise to become a key enabling technology for B2B e-commerce. One of the most-touted features of Web services is their capability to recursively construct a Web service as a workflow of other existing Web services. The quality of service (QoS) of Web-services-based workflows may be an essential determinant when selecting constituent Web(More)
Recent work on continuous queries has focused on processing queries in very large, mobile environments. In this paper, we propose a system leveraging the computing capacities of mobile devices for continuous range query processing. In our design, continuous range queries are mainly processed on the mobile device side, which is able to achieve real-time(More)
Location-based services are increasingly popular and it is a key challenge to efficiently support query processing. We present a novel design to process large numbers of location-based snapshot queries on MOVing objects in road Networks (MOVNet, for short). MOVNet's dual-index design utilizes an on-disk R-tree to store the network connectivities and an(More)
Location-based services are increasingly popular. In this paper, we present our novel design of a system to process location-based queries on MOVing objects in road Networks (MOVNet, for short) that efficiently handles a large number of spatial queries over moving objects in a stationary road network. MOVNet utilizes an on-disk R-tree to store the network(More)
Nearest neighbor (NN) searches represent an important class of queries in geographic information systems (GIS). Most nearest neighbor algorithms rely on static distance information to compute NN queries (e.g., Euclidean distance or spatial network distance). However, the final goal of a user when performing an NN search is often to travel to one of the(More)
With the proliferation of mobile devices, an increasing number of urban users subscribe to location-based services. This trend has led to significant research interest in techniques that address two fundamental requirements: road network-based distance computation and the capability to process moving objects as points of interests. However, there exist few(More)
Web services promise to become a key enabling technology for B2B e-commerce. Several languages have been proposed to compose Web services into workflows. The QoS of the Web services-based workflows may play an essential role in choosing constituent Web services and determining service level agreement with their users. In this paper, we identify a set of QoS(More)
The distributed hash table (DHT) mechanisms have been proposed to manage data in very large, structured peer-to-peer (P2P) systems. DHT algorithms provide efficient exact-match object search capabilities without requiring global indexing and are hence extremely scalable. However, range queries - which are very common with spatial data - cannot be executed(More)
Nearest neighbor (NN) searches represent an important class of queries in geographic information systems (GIS). Most nearest neighbor algorithms rely on static distance information to compute NN queries (e.g., Euclidean distance or spatial network distance). However, the final goal of a user when performing an NN search is often to travel to one of the(More)