Information Technology Reference
In-Depth Information
Figure 1.Life cycle of a servlet
In our implementation, we have created an XML
schema with medical information representing the
patient's record, and we dynamically translate it to
an xHTML (Chuck Musciano and Bill Kennedy,
2006) page applying the XSLT template that cor-
responds to the capabilities class of the request-
ing terminal device (Eric M. Burke, 2001). With
respect to the standardised technologies above,
the xHTML standard is currently supported by
all modern browsers. The XML is a declarative
language that enables the exchange of data across
domains enhancing the interoperability. In particu-
lar, it gives the user the freedom to organise and
store data with tags and forms in a free-will manner.
(Elliotte Rusty Harold, W. Scott Means, 2004).
With XML it is very easy to produce a web page
in HTML or xHTML, which will be easily read
by anyone aware of the associated XML schema.
This is where the XSLT templates come into play.
With the XSLT code, which is close enough to
the XML structure, we can translate the XML
schema into a web page, filtering at will the data
in the XML file and organizing its presentation
with xHTML commands. The content of a XSLT
can look like Exhibit 3.
To achieve this conversion it is required the
mediation of a XSL (Extensible Stylesheet Lan-
guage) processor to undertake the translation of
XML into xHTML with the use of XSLT. This
task is automatically performed by various tech-
nologies including Java (Eric M. Burke, 2001).
Figure 2 illustrates the operation of a XSL proces-
sor.
Comparing to other CGI technologies, the
Servlets provide faster processing of requests due
to the fact they apply multi-threading techniques
(multithreading wikipedia); hence, at the same
time other technologies process a single GET or
POST request, servlets can serve many. In addi-
tion, servlets work on the existing thread of a
process, saving the system resources for creating
their own ones. Furthermore, the servlets' persis-
tence in the system memory between requests
processing, facilitates the host machine to just
send a pending request to the same instance of a
servlet, saving, thus, the time needed to create a
new one. As far as security is concerned, the
servlets are executed at their own private space
using their own resources. Hence, a servlet's
failure or a roque-like program (e.g. a virus), af-
fects only the dedicated system resources, without
jeopardizing the stability of the whole system.
Another advantage towards ubiquitous service
provision is that Java servlets also enable the
dynamic creation of customised web pages with
the use of XSLT (Extensible Stylesheet Language
Transformations) templates (Doug Tidwell, 2008).
FRAMEWORK FOR DYNAMIC
CONTENT ADAPTATION TO
TERMINAL CAPABILITIES
Issues and Controversies
with the Standards
Retrieving a UAProf attribute value is not as simple
as retrieving the value of an HTTP header like
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