A general characterization of integrating and querying heterogeneous fuzzy spatiotemporal XML data

With the continuous expansion of spatiotemporal applications, spatiotemporal data has been widely used in various fields. Because XML (eXtensible Markup Language) has been the de-facto standard for representing and exchanging data on the Web, and fuzziness is an inherent feature of most spatiotemporal applications, researches on fuzzy spatiotemporal XML data have received increasing attention. Although XML has been employed to represent and query fuzzy spatiotemporal data, relatively little work has been carried out to integrate heterogeneous fuzzy spatiotemporal data. More importantly, current efforts do not take global and local cases into account when representing and querying heterogeneous fuzzy spatiotemporal XML data. In this paper, after presenting fuzzy spatiotemporal data based on XML, we propose an integration model for fuzzy spatiotemporal XML data. Then, feature expression and field mapping table are used to decompose the query, and the local data sources that do not exist in the query results are excluded to improve the query efficiency. Then, using the information in the feature expression, the XQuery query language is transformed into the query language corresponding to the local data source. After getting the results of each local data source, the semantic heterogeneity is eliminated by using field mapping table, and the query results are uniformly described as data source views by using XML Schema. Finally, the query results are screened and combined by using the query conditions stored in the query decomposition process. This query process shields the semantic heterogeneity and structural heterogeneity of the underlying data source, and ensures the transparency of user query. Finally, the presented instance show that our approach is correct, and the experimental results show the performance advantages of our approach.