A distributed, scalable and provenance-enabled data access protocol for spatial data infrastructure

This paper proposes a new model for data access and sharing within a spatial data infrastructure. Spatial data infrastructure, often proposed at national level, refers to the enabling of wider access to geographical data so that better knowledge can be generated to promote social, environmental and economic benefits. A good spatial data infrastructure includes people, policies, tools, methods and data. Many national spatial data infrastructure projects have included a clearing house, where meta-data can be searched in order to discover digital resources. While this approach can have certain advantages, there are also problems. Particularly the centralised clearing house has been shown to be hard to realise. In this paper, instead of a centralised top-down approach, we advocate a scalable, bottom-up distributed approach as the core of a spatial data infrastructure and demonstrate its feasibility. The advantage of this approach is that the spatial data infrastructure can grow organically without the need of a centralised entity and thus access to spatial data can be achieved sooner bringing with it environmental and economic benefits. We show how quality and security can be maintained within the approach. The National Geospatial Data Infrastructure (NGDI) project of Nigeria, together with the application area of environmental impact analysis, is used as a case study.