them but also by trying to simplify the
process through better integration of
the tools themselves.
Information integration is currently a brittle process; changing the structure of just one data source can force
an integration redesign. This problem
of schema evolution32 has received
much attention from researchers; but
surprisingly few commercial tools that
might reduce the cost of integration
are available to address the problem.
Another cause of brittleness, and another topic of research, 9 arises from
the complex rules for handling the
inconsistencies and incompleteness
of different sources. One possible approach, for example, is to offer a tool
that suggests minimal changes to
source data, thereby eliminating many
of the unanticipated inconsistencies.
Most past work has focused on the
problems of information-technology
shops, where the goal of integration is
usually known at the outset of a project. But some recent work addresses
problems in other domains, notably
science, engineering, and personal-information management. In these
domains, information integration is
often an exploratory activity in which
a user integrates some information,
evaluates the result, and consequently identifies additional information
to integrate. In this scenario, called
“dataspaces,” 17 finding the right data
sources is important, as is automated
tracking of how the integrated data
was derived, called its “provenance.” 34
Semantic technologies such as ontologies and logic-based reasoning engines may also help with the integration task. 19
Information integration is a vibrant
field powered not only by engineering innovation but also by evolution
of the problem itself. Initially, information integration was stimulated by
the needs of enterprises; for the last
decade, it has also been driven by the
desire to integrate the vast collection
of data available on the Web. Recent
trends—the continual improvement
of Web-based search, the proliferation
of hosted applications, cloud storage,
Web-based integration services, and
open interfaces to Web applications
(such as social networks), among others—present even more challenges to
the field. Information integration will
keep large numbers of software engineers and computer-science researchers busy for a long time to come.
We are grateful to Denise Draper, Alon
Halevy, Mauricio Hernández, David
Maier, Sergey Melnik, Sriram Raghavan, and the anonymous referees for
many suggested improvements.
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Philip A. Bernstein ( email@example.com) is a principal
researcher in the database group of Microsoft Research in
Laura M. haas ( firstname.lastname@example.org) is an IBM
distinguished engineer and director of computer science at
the IBM Almaden Research Center in San Jose, CA.