Information Technology Reference
In-Depth Information
For demonstration purposes we present and
evaluate the WURFL-based solution we have
developed for a hospital environment. Our in-
formational web-like service provides to the
authorized medical users of the hospital intranet
updated information related to their patients.
The information is retrieved from an associated
repository of patients' clinical data and is presented
properly adapted to the wireless devices that the
medical personnel carry with in the premises of
the hospital. The system incorporates the required
intelligence to discriminate the access context
of each user, such as the hardware and software
capabilities of each requesting client and/or the
networking technology used, adapting appropri-
ately the presentation of the submitted content to
the respective profiles. It is underlined that only
one entry point to the application is provided.
That is, all clients, wired or wireless, access the
same Web page-like interface for interrogat-
ing the service. The module of our system that
implements the user interface accommodates the
required intelligence to distinguish the capabilities
of each connected device and adapt accordingly
the presentation of the submitted response. Obvi-
ously, the challenge is how the request handling
server of the service can detect the effective level
of capabilities of the requesting device, so the cli-
ent receives the requested content in a form that
its terminal device can properly present. What
it includes is, at first, classification of the client
capabilities that are detected via WURFL, to one
of the capabilities' classes we have created for the
various wireless devices and then, adaptation of
the requested medical content retrieved from the
underlying repository to the terminal capabilities
of the requesting client device. Data and records
to/from the repository are encoded in XML for in-
teroperability issues. Furthermore, the appropriate
XSLT templates (one for each device capabilities
class) (Doug Tidwell, 2008; Eric M. Burke, 2001)
have been created for adapting and transforming
the patients' XML records from the repository
into web pages (e.g. in HTML, xHTML (Chuck
Musciano and Bill Kennedy, 2006)) presentable
to the execution context of the requesting device.
The chapter is organized as following: at first
we introduce to the standardized technologies
and mechanisms for terminal capabilities an-
nouncement and negotiation (CC/PP, UAProf,
MPEG-21) and to the technologies provided for
ubiquitous service creation and adaptation (e.g.
Java servlets, XML, XSLT). Then we discuss the
controversies and problems associated with the
adoption of standards in realistic implementations
and we introduce to the associated WURFL solu-
tion, justifying thus our decision to rely on it our
development. Following, we present some detail
from our service development emphasizing on
the issue of terminal devices' classification, the
patients' medical record in XML, the XSLTs for
each terminal class, the main Servlet engine and
the resulting web pages. Presentation is enriched
with appropriate screenshots. Finally, we conclude
the chapter with the open issues for future research
and a short synopsis of the whole effort.
BACKGROUND
The client-server model is the dominant com-
puting model in Internet. Most popular Internet
services, including WWW (World Wide Web),
obey its rules. In particular, it is a distributed appli-
cation structure that partitions tasks or workloads
between the providers of a resource or service,
called servers, and service requesters, called cli-
ents (Client-Server model wikipedia). Although
not required, normally clients and servers run
on separate hardware and communicate over a
computer network. Hence, a server machine is a
host that shares its resources with clients. A client
does not share any of its resources, but requests
a server's content or service function. Clients
therefore initiate communication sessions with
servers which await (listen for) incoming requests.
Communication between clients and servers is
implemented via the exchange of messages of
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