Swoogle
A Search Engine for Semantic Web Documents
Swoogle is a crawler based search an retrieval system for semantic web documents. It first started as a research project and now it is developed with a goal to providing a search engine for semantic web. Semantic web is a web of Semantic Web Documents (SWDs) which is an online document written using RDF or OWL, so we can say that semantic web is a distributed online repository of SWDs.
The Swoogle extracts meta data from the document and indexes into system for later searches and queries. Apart from that, the Swoogle crawler can be viewed as a focused crawler which can crawls and find relevant documents. This also provides services to human users through a browser interface and to software agents via RESTful web services while collecting these documents in a more systematic way. We can retrieve both ontologies and instances that are physically distributed on web.
The above diagram displays the architecture of the Swoogle search engine. It includes processes like analysis, indexing, discovering, servicing etc. This architecture is build upon several components. Those are meta data creation component, indexation and retrieval component, data analysis component, SWD discovery component and the user interface.
We need to make sure that newly added ontologies will not be just distributed randomly over the Web but will be collected and used to facilitate intelligent decisions. We need to focus more on reusing existing ontologies if it meets are need otherwise there will be no common understanding resulting zero interoperability and there would be no global processing. The Swoogle supports this objective by collecting all the relevant ontologies as per your need. This is the main use of the Swoogle search engine. Apart from searching ontologies, instances we can search by terms as well as with constraints in classes or properties if we want.
The navigation property is another important aspect of the Swoogle which is provided by the namespaces of the documents. This ability gives the support to understand the structure of semantic web and internal links. The Swoogle does several types of crawling such as meta crawling, bounded html crawling, RDF crawling etc. In Swoogle, the semantic web archive is there to help user to check if a URI has been indexed and to track the previous versions of Semantic Web Documents.
