Continuous Query And Analysis Services For Vessel Trajectory Data

Streaming data is a new form of data,which has the characteristics of continuous,dynamic and high-speed arrival.In recent years,with the emergence of more and more TOT systems and data platforms based on mobile sensing devices,the scale of streaming data has increased dramatically,and more and more attentions have been paid to the query of streaming data.Vessel trajectory data is a kind of streaming data,utilizing this data to analyze the abnormal behaviors of vessels in real time is of great significance to guarantee the safety of navigation.However,such data platforms usually do not directly expose their own underlying data sources for users to query and analyze.How to access and analyze the vessel trajectory data quickly and efficiently based on such a premise has become an urgent problem to be solved.To solve this problem,this paper proposes an approach of encapsulating the underlying streaming data source through data service,and then answering the user query request with high complexity through data service composition.The work of this paper is detailed as follows:1)A continuous data service model considering the time-varying characteristics of streaming data is proposed,which continuously updates its output results with the continuous arrival of underlying streaming data.This model has the same characteristics as the output mode of materialized view in the database,so that it can be regarded as a materialized view built on the streaming data source.The difference is that the continuous data service can receive flexible instantiation parameters,thus becoming a view with variable definitions.2)Inspired by the issue of view-based query rewriting in the field of traditional data integration,this paper proposes two continuous data service composition algorithms,SBucket(Service Bucket)algorithm and SMiniCon(Service MiniCon)algorithm,they both can automatically,quickly and accurately generate the executable service composition plans from a large number of continuous data services.3)The feasibility and accuracy of the proposed method were verified based on real ocean trajectory data and cases,and sufficient experiments were conducted to prove the efficiency of the proposed method.4)Develop a set of continuous data query and analysis prototype system for vessel trajectory data,which has the functions of continuous data service registration,user query submission,automatic generation of service composition plan and result analysis,etc.