Research On Key Technologies Of A Distributed Web Map Service Platform

In recent years, with the rapid development of geographic information industry, the problem of platform diversity and data heterogeneity between Web GIS(Web Geographic Information System) has become increasingly prominent, the demand for collaboration between various Web GIS platforms has also increased. To solve these problems,we need to achieve a standard mode to share and interoperate map data, and to choose a technology which is independent of platform and data storage structure.After learning and understanding OGC-GIS standards, we designed and implemented a distributed web map service platform based on the Spring Framework and ICE distributed framework, which includes the map service subsystem, the map service organization and management subsystem and the cluster monitoring and management subsystem. The main contributions of this thesis are as follows:1. We proposed a scheme for the map service platform based on the analysis of the overall demand and design goals of the distributed system. The platform consists of three main subsystems including the map service subsystem, the map service organization subsystem and the management subsystem. Then, we introduced the architecture(including logical architecture and physical architecture) of the service platform and the features of each subsystem.2. We designed and implemented a web services layer dedicated to the map service subsystem. Implemented three modules including the access control module, the buffer module and the load balancing module, which ensuring the efficient routing of map service requests, based on Nginx HTTP filtering and the third-party modules. Implemented a map service discovery module and several web map service components on the basis of Spring MVC framework, OGC-GIS standards and ICE development framework, which ensured that the service request after routing to get a fast and accurate response.3. We proposed three abstractions which are data source, service instance, service space for the map service organization and management subsystem. Designed and implemented a scheme to organize and manage data source, service instance and service space effectively based on Spring MVC.4. We divided the monitoring of all kinds of servers into two modules, i.e. service module and client module for the cluster monitoring and management subsystem respectively. Service module is a background process deployed on the monitored machine, waiting for the instructions of connection and monitoring from Client module. All Client modules are integrated into the cluster web application, which provides unified HTTP service interfaces.The platform has been tested in the following aspects, including OGC-GIS map services, the map service organization and management subsystem, and the cluster monitoring and management subsystem. The test result suggests that the distributed web map service platform has achieved the function of standard map data sharing and interoperability as expected.