  RESTful services on the Web expose information through retrievable resource
representations that represent self-describing descriptions of resources, and
through the way how these resources are interlinked through the hyperlinks that
can be found in those representations. This basic design of RESTful services
means that for extracting the most useful information from a service, it is
necessary to understand a service's representations, which means both the
semantics in terms of describing a resource, and also its semantics in terms of
describing its linkage with other resources. Based on the Resource Linking
Language (ReLL), this paper describes a framework for how RESTful services can
be described, and how these descriptions can then be used to harvest
information from these services. Building on this framework, a layered model of
RESTful service semantics allows to represent a service's information in
RDF/OWL. Because REST is based on the linkage between resources, the same model
can be used for aggregating and interlinking multiple services for extracting
RDF data from sets of RESTful services.
