Open Sahara Server, the open source semantic web server, includes a pluggable API for adding smart search, query and analysis functionality. Open Sahara can be used to analyse and annotate documents from the Internet or intranets. The resulting knowledge can be queried, and Open Sahara can present the query results as feeds, charts, or even overlays on a map. This article will show how to create map overlays.
We will use the OpenLayers javascript library to display a map, and use the Open Sahara REST-based query API to show matching documents as a cluster layer on top of that map. Such a cluster layer is a nice way to show which areas of a region have many matches and which areas have few matches. Knowledge of the OpenLayers javascript library is assumed. The article demonstrates to Open Sahara REST API to represent search results as a map cluster-layer.