Proceedings of the 3rd ACM international workshop on Data warehousing and OLAP
pygrametl: a powerful programming framework for extract-transform-load programmers
Proceedings of the ACM twelfth international workshop on Data warehousing and OLAP
3XL: Supporting efficient operations on very large OWL Lite triple-stores
Information Systems
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As more and more information is available on the web, it is a problem that many web resources are not accessible, i.e., are not usable for users with special needs. For example, for a web page to be accessible, it should give text alternatives (i.e., explanatory texts) for images such that blind users that have the web pages read aloud automatically also can obtain information about the images. In the European Internet Accessibility Observatory (EIAO) project, a crawler that will evaluate the accessibility of thousands of European web sites is built. The crawler frequently performs many tests of the web sites and thus very large amounts of accessibility data are generated. Based on open-source software, a data warehouse (DW) called EIAO DW is built to make analysis of the complex accessibility data easy, reliable and fast. The EIAO DW is, thus, a data warehouse which measures properties of the web or, in other words, a web warehouse. It is believed that this work is the first to address the application of business intelligence (BI) techniques to the complex field of accessibility in a general and scalable way. This paper describes how the EIAO DW is designed and built. The paper introduces accessibility and the EIAO project to give a background for the design of EIAO DW. Then, the conceptual, logical and physical models are presented. The paper also gives descriptions of the complex Resource Description Framework (RDF) source data and complex accessibility aggregation functions supported by EIAO DW.