  In this study, a novel metacrawling method is proposed for discovering and
monitoring linked data sources on the Web. We implemented the method in a
prototype system, named SPARQL Endpoints Discovery (SpEnD). SpEnD starts with a
"search keyword" discovery process for finding relevant keywords for the linked
data domain and specifically SPARQL endpoints. Then, these search keywords are
utilized to find linked data sources via popular search engines (Google, Bing,
Yahoo, Yandex). By using this method, most of the currently listed SPARQL
endpoints in existing endpoint repositories, as well as a significant number of
new SPARQL endpoints, have been discovered. Finally, we have developed a new
SPARQL endpoint crawler (SpEC) for crawling and link analysis.
