Infrastructural Layer. The architecture is composed by four main layers as seen in
Figure 1. AAL applications often use devices such as sensors, adapters, mobile devices,
desktop computers, among others. These kind of devices represent the Infrastructural
Layer. Given that devices may be added or removed from the system dynamically, we
impose that devices included in this layer must be made accessible via Web Services,
to be encapsulated and accessed from a service level layer. For this, devices should
be introduced via a “Device as a Service” paradigm [2], which allows devices to be
accessible via a well defined interface.
Common Services Layer. The Common Services Layer is responsible for providing
services such as access between nodes, monitoring, security and user management. We
intended for services in this layer to include third-party services which may be needed
by certain applications. In order to facilitate the location of certain business logics, we
established that any service within the architecture must advertise itself in the service
registry. Technologically, the registry, running at a central server accessible to all nodes,
functions like a WSDL [9] repository.
Living Lab Services Layer. The Living Lab Services layer aims to involve all pos-
sible services that may arise, either from the implementation of certain devices, (for
instances, a video capture service), either from the development of new services (like
a sensor service), or either from the inclusion of already existing exterior services (a
monitoring service) that may be needed in the development of certain applications. To
comply with the user-centric paradigm associated to the project, it is expected that built
applications follow user-friendly and user-adaptable paradigms. To help them, this layer
includes services like context and user modeling providing applications with means to
better know the end user and achieve user adaptation.
Applicational Layer. In the top layer, the architecture includes an Applicational layer
where developed applications should be “placed”. An important requirement that ex-
isting SOA proposals didn’t meet was the inclusion of multimodal capabilities. In our
view, to establish maximum usability, multimodality must be also included. The telere-
habilitation application which will be later explained is one such example.
3 Infrastructure
In the conceptual architecture, a layer of services was established exclusively focused
on integrating specialized services to be developed as part of the LUL project - Liv-
ing Lab Service Layer. These services require a physical location where they can be
deployed. In this sense, two options came up: to use a central server accessible by all
project nodes (scalable to a large increase in a more realistic AAL scenario) or to use
a smaller home based server. We selected a subset from both due to the differences in
the envisioned services. While some are generic and must be made available at a well
known address, others are more “house oriented”.
Our option for LUL is divided into two parts, to have a central server (named LUL
server) where generic services can be deployed and published being complemented by
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