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work, evaluation, and conclusions about the current
state of this research and future directions.
methodologies have not changed drastically. Even
the introduction of Web service standards (Ferris
& Farrel, 2003) has earned much of its furor from
the political buy-in of major vendors, rather than
from conceptual innovations.
Microsoft has introduced the first WPC plat-
form with their Digital Dashboard initiative (Har-
mon et al., 2000). WPC components are called
Web parts in this architecture. More recently,
the WebPart model has been integrated with the
.Net component framework and is now supported
by Microsoft's product Sharepoint Portal Server.
Similar WPC platforms have been developed by
the .Net open source community, for example,
DNN and Rainbow. Vendors involved in Java
technology have released comparable platforms
for Java WPCs called Portlets, for example, IBM's
Websphere Portal Server and Sun's Java System
Portal Server. Recently, the Java Community
Process (JCP) has generated the final release of
the Java Specification Request “JSR 168” for
standardising the WCP model for Java (Introduc-
tion to JSR, 2003). While there are individual
differences and variations among these WPC
platforms, they share the objective of creating a
market for user-composable visual components
in Web applications.
Component models For the
web: wpC teChnology in
perspeCtive
The emergence of Web portal component models
can be considered the most recent milestone in
a timeline of standards introduced over the last
decade for the purpose of constructing component-
based software for Web-centric applications (cf.
Figure 1). However, WPC components are signifi-
cantly different from earlier component models with
respect to the fact that they cross-cut layers of the
classical three-tier architecture for Web-centric
information systems (presentation, application,
and data layer) (Vidgen, Avison, Wood, & Wood-
Harper, 2002). Component models introduced
earlier target specific layers, for example, the
middle-tier (EJB, COM+, etc.) and the presenta-
tion layer (ActiveX, JavaBeans, etc.). Another
remarkable feature of WPC technology is that it
enables end-user-based component composition.
The potential impact of this technology is immense
and might revolutionise the way Web applications
will be developed and used in the future.
Prior to the introduction of WPC platforms, there
have been little fundamental changes to the way
Web applications are engineered and used during
the last decade. While languages and component
frameworks have evolved over time, underlying
a Composition model for
web portal Components
We now present a conceptual model for the event-
based composition of WPCs, which serves as a
Figure 1. Component models for Web-based software
ActiveX
JavaBeans
000
MS WebParts
00
DNN Modules
00
Rainbow Modules
000
00
00
00
00
CORBA /w IIOP
DCOM
COM+
EJB
000
SOAP
SunOne, .NET
00
IBM Portlet API
00
JSR
(JCP)
 
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