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not able to explore resources that may be available in the physical environment.
Without the assistance of a local infrastructure, these applications do not have
the potential for reaching the same level of richness and context-awareness as the
ubiquitous computing applications created for a specific physical infrastructure.
This research aims to combine the two previous approaches, and is specifi-
cally targeted at the issues of interoperability and seamless integration between
a user home environment (e.g. a MNO portal) and the ubiquitous computing
environments corresponding to the physical locations visited by the user. Our
approach introduces the concept of Value ADded Environment (VADE) as an
administrative and physical domain, e.g. a shopping center or an airport, where
the locally available ubiquitous computing facilities can be combined with the
external home environment of visiting users. The overall scenario is that when
entering a VADE, mobile users are provided with functionality that corresponds
to the dynamic combination of predefined user preferences, currently active ap-
plications, current user context and locally available services and applications.
While this research copes with multiple challenges, this paper focuses only on
the integration of lo cal resources into an external environment. The paper de-
scribes the main issues implied in the integration between local and external
environments, namely interoperability and performance, using the VADE sys-
tem as a representative example of the integration challenges. The paper argues
for the need for an integration middleware dealing with the identified issues, and
describes the solution we developed for the VADE system. For a more complete
description of the VADE system and other aspects covered by this research,
please refer to [2].
The next section describes the VADE concept, its application models, and
the system architecture. Section 3 introduces the issues of dynamically integrat-
ing local applications and services into the user home environment. Section 4
explains how we dealt with those integration issues by the use of a VADE-aware
integration middleware.
2 Value Added Environment
The VADE concept is here presented as an example of integration between local
and external environments. The idea behind this concept is that when a user
enters a ubiquitous computing environment that also happens to be a VADE sys-
tem, the functionality available to that user should be the combination of global
and local functionality. In order to clarify these relationships, we have grouped
the overall system functionality into three separate domains, more specifically:
User, VADE, and External domains. The User domain corresponds to the physi-
cal and logical elements carried by a p er son that is within the physical b oundaries
of a VADE. The VADE domain corresponds to elements constituting the local
infrastructure and directly supporting the VADE functionality (e.g., services,
applications, and all sorts of devices – sensors, input/output, etc.). Finally, the
External domain corresponds to all the other elements that interact with the
VADE but are not part of the VADE, or user domains. Our main assump-
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