Swoogle

It is a semantic web search engine and also it is a research project in the Computer Science and Electrical Engineering Department at the University of Maryland. We can use it to find documents on semantic web. We can see a home page at http://swoogle.umbc.edu/, running since 2004. It use a system of crawlers to discover RDF documents and HTML documents with embedded RDF content. It provide a browser interface and to software agents via RESTfull web services. So, Swoogle is an attempt to mine and index this new set of web documents.

This Swoogle engine performs crawling of semantic documents like most web search engines and the search is available as web service too. So, It is primarily written in Java with the PHP used for the front-end and MySQL for database. We can search over 10,000 ontologies, indexes more that 1.3 million web documents and compute importance of semantic web documents. And It also also mining the documents for inter-relationships that are the basis for the semantic web.

It uses an adaptive crawler to discover documents with RDF content. Services are provided to both humans and programs.

It was designed with several use cases in mind. It is very useful for Semantic Web developers and researchers to discover useful ontologies or terms and to collect data on properties of the Semantic Web. It currently uses Google to find initial seed documents that are likely to be SWDs (Semantic Wed Documents). Other seeds come from user submissions. We know SWDs use .rdf, .owl as their file extensions, So, Swoogle queries for files with such extensions. We know Google return at most 1000 results for any query. Swoogle takes advantage of its feature that restricts a search to results from a specified domain or site. Swoogle uses two custom ranking algorithms There are OntoRank and TermRank, it help to order a collection of SWDs or terms, respectively.

It performs a very modest amount of reasoning using RDFS and OWL semantics due to the computational cost and potential for inconsistencies in
dealing. r, It does compute many useful properties and still more can be easily derived from the information in its database.