Semantic Composition of Web Portal Components - End User Computing Challenges and Technologies: Emerging Tools and Applications - page 169

Early Web portals were little more than frequently
updated or database-driven Web pages and users
had only very limited options for personalising the
information content provided. Since then, portals
have become increasingly customisable. Many cur-
rent portal sites provide the means to personalise
information content and to customise the way in
which this content is rendered on the screen.
Recently, there has been an increasing trend of
employing Web portals within organisations to pro-
vide a unified and personalised user interface for
all relevant information content, and to facilitate
collaboration in virtual enterprises. The metaphor
of a digital “dashboard” has been coined to describe
such intranet portals, which enable users to choose
from a gallery of information components in order
to customise their individual information delivery
(Harmon, Conroy, Emory, & Macfarlane, 2000). A
number of dedicated portal server technologies have
been developed by software vendors such as Sun
Microsystems, Microsoft, IBM, Bea, and the open
source community. Such portal servers implement
extensible frameworks for a new kind of software
component. We will refer to these components as
Web portal components (WPCs) in order to avoid
vendor specific terminology such as Web parts
(Baron, 2003), portlets (Buckner, Hesmer, Fischer,
& Schuster, 2003), or modules (DNN, Rainbow)
(Schultes, 2003).
AninnovativefeatureofWPCtechnology is based
on end-user composition of Web sites. Moreover, in
some WPC models, users not only visually compose
pages of WPCs with their Web browsers but they
can also create connections between the interfaces
of these components in order to let them exchange
data. This feature carries great promise because it
empowers users, in principle, to construct inte-
grated forms based on WPCs.
While current WPC technology is satisfactory
for simple applications and relatively static portal
pages (i.e., pages that are largely predefined and
modified infrequently), a number of problems arise
with complex, more frequently modified portal
applications. As an example for such an application,

we have been studying the Web based delivery of
electronic medical record (EMR) services to health
care professionals. The challenge in developing EMR
applications consists of the large variety of poten-
tially important information dialogues and forms.
Moreover, physicians have different specialisations
and preferences about their interaction with EMR
information content. At first glance, WPC technol-
ogy appears to be an ideal platform for building
EMR applications, because it enables caregivers
to compose personalised medical patient records.
However, “on-the-fly” composition of WPC-based
pages turns out to be difficult and error-prone in
practice.
The main cause for this limitation is that
WPC event interfaces are not semantically typed.
This may result in a confusingly large number of
technically possible event connections offered to
the user during WPC composition. In this chapter,
we present an approach to overcoming this limita-
tion by associating semantic concepts with WPC
event interfaces. This approach allows us to shift the
WPC composition paradigm from the technology
domain (which is unfamiliar to most end users) to the
actual application domain of the portal user. Rather
than creating event connections among WPCs, the
user can simply specify a domain-specific context
information model, which serves as input for creat-
ing the connections among WPCs.
The next section will discuss how the new WPC
paradigm relates to other component technologies for
the Web. In the third section, we conceptualise the
event composition model in current WPC platforms
and discuss its limitations for dynamic applications,
in which end users frequently need to compose
new portal pages on-the-fly. The fourth section
represents the technical core of this chapter: we
present an approach to facilitating end-user-driven
composition of portal pages by moving the WPC
composition paradigm from a technological level to
a domain-oriented level. A case study for applying
this approach is discussed in the fifth section. The
final two sections close with a comparison of related