Dynamic metadata query algorithm of high-speed railway basic data based on heterogeneous integration

The goal of sharing high-speed railway basic data is to integrate discrete data resources in order to establish service-oriented data sharing services architecture based on distribution and centralization and to support optimum design and operations management of high-speed railway transportation organization. In this paper a common metadata dictionary pattern is designed to meet the multiple requirements. It is composed by three main parts - representation of database network location, data schema and data content. This pattern supports upwards integrated access interface, and also provides the description for semantic-level common metadata retrieval. Based on the metadata dictionary, a dynamic query algorithm for multi-table changing of relevant databases with the changes of access requirements involved in a query is presented. The correctness of the algorithm has been proved in this paper.