Infomaster is an information integration system that pro-
vides integrated access tomultiple distributed heterogeneous
information sources on the Internet, thus giving the illu-
sion of a centralized, homogeneous information system. We
say that Infomaster creates a virtual data warehouse. The
core of Infomaster is a facilitator that dynamically deter-
mines an ecient way to answer the user's query using as
few sources as necessary and harmonizes the heterogeneities
among these sources. Infomaster handles both structural
and content translation to resolve dierences between mul-
tiple data sources and the multiple applications for the col-
lected data. Infomaster connects to a variety of databases
using wrappers, such as for Z39.50, SQL databases through
ODBC, EDI transactions, and other World Wide Web
(WWW) sources. There are several WWW user interfaces
to Infomaster, including forms based and textual. Infomas-
ter also includes a programmatic interface and it can down-
load results in structured form onto a client computer. In-
fomaster has been in production use for integrating rental
housing advertisements from several newspapers (since fall
1995), and for meeting room scheduling (since winter 1996).
Infomaster is also being used to integrate heterogeneous elec-
tronic product catalogs.