Fangyan Rao

An efficient spatial publish/subscribe system for intelligent location-based services

The advance in wireless Internet and mobile computing brought the booming of intelligent Location-Based Services(LBS), which can actively push location-dependent information to mobile users according to their predefined interest. The successful development of push-based LBS applications relies on the existence of a publish/subscribe middleware that can handle spatial relationship. This paper presents an efficient spatial publish/subscribe system that can serve as the middleware for intelligent LBS applications. The basic models, including spatial event model, spatial subscription model and notification model, are introduced and the over-all architecture is presented. Two kinds of spatial predicate that can meet most common requirement of intelligent location aware applications are also discussed. Furthermore, we propose a novel spatial event processing approach that dispatches the spatial subscriptions to self-positioning mobile devices. By leveraging client-side computing resource and decreasing the communication times, the server-side workload is relieved and the communication cost is reduced. Experimental results clearly demonstrate the efficiency of our approach.

Spatial hierarchy and OLAP-favored search in spatial data warehouse

Data warehouse and Online Analytical Processing(OLAP) play a key role in business intelligent systems. With the increasing amount of spatial data stored in business database, how to utilize these spatial information to get insight into business data from the geo-spatial point of view is becoming an important issue of data warehouse and OLAP. However, traditional data warehouse and OLAP tools can not fully exploit spatial data in coordinates because multi-dimensional spatial data does not have implicit or explicit concept hierarchy to compute pre-aggregation and materialization in data warehouse. In this paper we extend the traditional set-grouping hierarchy into multi-dimensional data space and propose to use spatial index tree as the hierarchy on spatial dimension. With spatial hierarchy, spatial data warehouse can be built accordingly. Our approach preserve the star schema in data warehouse while building the hierarchy on spatial dimension, and can be easily integrated into existing data warehouse and OLAP systems. To process spatial OLAP query in spatial data warehouse, we propose an OLAP-favored search method which can utilize the pre-aggregation result in spatial data warehouse to improve the performance of spatial OLAP queries. For generality, the algorithm is developed based on Generalized Index Searching Tree(GiST). To improve the performance of OLAP-favored search, we further introduce a heuristic search method which can provide an approximate answer to spatial OLAP query. Experiment result shows the efficiency of our method.

LORE: an infrastructure to support location-aware services

With the advance in wireless Internet and mobile computing, location-based services (LBS)--the capability to deliver location-aware content to subscribers on the basis of the positioning capability of the wireless infrastructure--are emerging as key value-added services that telecom operators can offer. To support efficient and effective development and deployment of innovative location-aware applications, a flexible and resilient middleware should be built as the enabling infrastructure. This paper presents the research and efforts made in the IBM China Research Laboratory toward developing an infrastructure that supports location-aware services. This infrastructure is based on a proposed location operating reference model (LORE), which addresses many major aspects of building location-aware services, including positioning, location modeling, location-dependent query processiug, tracking, and intelligent location-aware message notification. Three key components of the infrastructure--the location server, a moving object database, and a spatial publish/subscribe engine--are introduced in detail. The location server has a common location adapter framework that supports heterogeneous positioning techniques and industry-standard location application program interfaces (APIs). The moving object database manages the location stream and processes the location-based queries. The spatial publish/subscribe engine enables intelligent location-aware message notification. We also present some location-aware application demonstrations that leverage the LORE infrastructure. Part of our work has been tested in pilot projects with leading carriers in China and has been integrated into the IBM WebSphere® Everyplace® Suite.

An Approach to Enabling Spatial OLAP by Aggregating on Spatial Hierarchy

Investigation shows that a huge number of spatial data exists in current business databases. Traditional data warehousing and OLAP, however, could not exploit the spatial information to get deep insight into the business data in decision making. In this paper, we propose a novel approach to enabling spatial OLAP by aggregating on the spatial hierarchy. A spatial index mechanism is employed to derive the spatial hierarchy for pre-aggregation and materialization, which in turn are leveraged by the OLAP system to efficiently answer spatial OLAP queries. Our prototype system shows that the proposed approach could be integrated easily into the existing data warehouse and OLAP systems to support spatial analysis. Preliminary experiment results are also presented.

BlueLocator: enabling enterprise location-based services

BlueLocator, a framework enabling enterprise location-based services as well as an enterprise user locating and tracking system, is introduced in this paper. Privacy control in LBS is discussed and a report-to-chain based access control list assignment policy is shown as an example of how a privacy related rule can be used for applications.

CAMEL: A Moving Object Database Approach for Intelligent Location Aware Services

Advances in wireless Internet and mobile computing require a new service model for location aware services supporting push services and personalization services based on mobility patterns of mobile users. This paper presents a prototype of CAMEL (Continuous, Active Monitor Engine for Location-based Services), a high performance location management engine to support such intelligent location aware services. We introduce the location model employed by CAMEL, the component architecture and key components of CAMLE, including a Database component, Location Listener, Query Engine, Location Filter, Trigger Handler and Data Server. The component-based architecture facilitates easy deployment of CAMEL for meeting different service model, such as push service, moving object monitor and moving object data warehousing. Two spatial trigger processing mechanisms for Single Moving Object Trigger and Binary Moving Object Trigger, which play an important role in push-based location aware service, are presented in detail and their performance is analyzed.

Managing location stream using moving object database

Advances in wireless Internet and mobile computing require a new service model for location aware services to support push services and personalization services based on mobility patterns of mobile users. This paper presents a prototype of CAMEL (Continuous, Active Monitor Engine for Location-based Services), a high performance location stream engine to manage large numbers of moving objects in support of intelligent location aware services. We introduce the location model employed by CAMEL, the component architecture and key components of CAMEL, including a Database component, Location Listener, Query Engine, Location Filter, Trigger Handler and Data Server. Also we present an enhanced processing algorithm using Max-Velocity constraint for improving performance of Binary Moving Object Trigger.

Compatibility analysis and mediation-aided composition for BPEL services

In Service Oriented Architecture (SOA), the need for inter-service compatibility analysis has gone beyond what existing service composition/ verification approaches can handle. Given two services whose interface invocation constraints are described by Business Process Execution Language for Web Services (BPEL4WS, or BPEL), we analyze their compatibility and adopt mediation as a light weight approach, to make partial compatible services work together more adaptively, without changing their internal logic. We transform BPEL into service workflow net which is a kind of colored Petri net. Based on this formalism we first analyze the compatibility of two services, and then devise an approach to check whether there exists any message mediation so that their mediation-aided composition will not violate the constraints imposed by either side. Later the method for mediation generation is also introduced. Our approach is validated through a real life case and further research directions are pointed out.

Services ecosystem: towards a resilient infrastructure for on demand services provisioning in grid

The dynamic nature of the Grid environment brings challenges to the services provisioning technique. A major aspect of Grid is to match demands for services with resources. Since resources and demands are fluctuating, Grid services provisioning need to be adjusted accordingly in responding to changes. In this paper, we propose a novel approach, Grid services migration, to enabling services provisioning on demand. The major motivation is to achieve the desired Quality of Service (QoS) such as performance, reliability, and etc. of Grid services on resources assembled dynamically responding to dynamic demand. In this paper, the technical characteristics of Grid services migration and its taxonomy are introduced. The Grid service migration algorithms are also presented. The Grid services migration framework with MAPE (Monitor, Analyze, Plan, and Execute) loop is proposed based on Open Grid Services Architecture (OGSA) and the prototype named Services Ecosystem, a resilient infrastructure for services provisioning on demand in Grid is developed. Demonstrations and experiments are conducted and results are presented to illustrate the capabilities of Grid services migration.

Location aware messaging - integrating LBS middleware and converged services

With the advent of next generation communication infrastructure where Internet and telecommunication network could work together to provide converged services like (messaging, presence and call control), location-based services requires not only flexible and scalable middleware that supports three LBS service models: pull, poll and push, but also advanced converged service platform that supports LBS applications in future communication infrastructure. Motivated by a typical scenario that requires location aware converged services described in the paper, key techniques are identified for building such a system. Based on our ongoing research work on NextGen LBS middleware and converged service, we built a location-aware massaging system for coming visitors. By marrying LBS middleware and converged service platform, we experimented LBS running on converged service network, collected requirements of LBS applications to the converged service platform, and explored new features in LBS on the converged service platform. The overall architecture and key components of the LBS middleware and converged services are also presented