“…For instance, the Semantic Web Search Engine (SWSE) (Hogan, et al, 2011) adapts the architecture of the common Web search engines for the case of structured RDF data (it offers crawling, data enhancing, indexing and a user interface for search, browsing and retrieval of RDF data). Swoogle (Ding, et al, 2004) is a crawler-based indexing and retrieval system for the Semantic Web that uses multiple crawlers to discover Semantic Web Documents (SWDs) through meta-search and link-following, analyzes SWDs and produces metadata, computes ranks of SWDs using a rational random surfing model, and indexes SWDs using an information retrieval system. Sindice (Oren, et al, 2008) is an indexing infrastructure with a Web front-end and a public API to locate Semantic Web data sources such as RDF files and SPARQL endpoints.…”