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Specifying OLAP Cubes On XML Data
(Journal Edition) (Abstract)
On-Line Analytical Processing (OLAP) enables analysts to gain insight
about data through fast and interactive access to a variety of
possible views on information, organized in a dimensional model. The
demand for data integration is rapidly becoming larger as more and
more information sources appear in modern enterprises. In the data
warehousing approach, selected information is extracted in advance and
stored in a repository, yielding good query performance. However, in
many situations a logical (rather than physical) integration of data
is preferable. Previous web-based data integration efforts have
focused almost exclusively on the logical level of data models,
creating a need for techniques focused on the conceptual level. Also,
previous integration techniques for web-based data have not addressed
the special needs of OLAP tools such as handling dimensions with
hierarchies. Extensible Markup Language (XML) is fast becoming the new
standard for data representation and exchange on the World Wide
Web. The rapid emergence of XML data on the web, e.g.,
business-to-business (B2B) e-commerce, is making it necessary for OLAP
and other data analysis tools to handle XML data as well as
traditional data formats.
Based on a real-world case study, this paper presents an approach to
specification of OLAP DBs based on web data. Unlike previous work,
this approach takes special OLAP issues such as dimension hierarchies
and correct aggregation of data into account. Also, the approach works
on the conceptual level, using Unified Modeling Language (UML) as a
basis for so-called UML snowflake diagrams that precisely capture the
multidimensional structure of the data. An integration architecture
that allows the logical integration of XML and relational data sources
for use by OLAP tools is also presented.
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