A context-driven geospatial web service approach towards the design of situational awareness maps
The recent development of internet-based map services has dramatically change how geospatial information is presented to users, novice or professional, for improving the quality and convenience of daily lives. Especially with the innovated internet and computer graphic technology, current map services are designed with comprehensive cartographic considerations and can be simultaneously accessed by multiple clients, with which users can metaphorically establish their understanding towards the phenomena in reality, regardless of where they are. Despite location-based services become increasingly popular, the serviced contents are nevertheless often “static” and the illustration seldom or even fail to adapt to the needs of presenting continuously or periodically changing situations in the real world. From the perspective of intuitive map reading, we argue it is necessary to include the needs of “situational awareness” into the design of map services, so as to improve the human computer interactions in the clients’ application environments. A context-driven approach for the design and mashup of map services are proposed. We first identify three types of map services, namely, reference map services, application-oriented map services and atomic map services. The context of each map services are analysed based on the considerations of theme, time, weather and transportation and described by a set of pre-defined “keywords.” These standardized keywords enable application developers to define rules to select map services with correct contexts and mashup them to meet particular situation needs, e.g., a rainy day map or an emergency medical map services. As the selected map services are already defined with context considerations, their mashup results would be automatically adjusted according to the situations acquired from the clients. By enriching the situational context and enhancing the transparent access of individual map services, a flexible and powerful bridging relationship can be built between the application developers and domain service providers. The proposed approach is hence not only an innovated thinking for designing map services, but should also be seen as a crucial strategy for facilitating interoperable application environments for the ecosystem of the National Spatial Data Infrastructure.