Webbases are database systems that enable creation of Web applications that
allow end users to shop around for products and services at various Web
sites without having to manually browse and fill out forms at each of these
sites.  In this paper we describe XRover which is an implementation
of the physical layer of the webbase architecture. This layer is primarily
responsible for automatically locating and extracting dynamic data from Web
sites, i.e data that can only be obtained by form fill-outs.  We discuss
our experience in building XRover using FLORA, a deductive object-oriented
system.