Model-driven Web Services Development
Roy Grønmo, David Skogan, Ida Solheim, Jon Oldevik
SINTEF Telecom and Informatics, Forskningsveien 1, N-0314, Oslo, Norway
{ roy.gronmo | david.skogan | ida.solheim | jon.oldevik }@sintef.no
Abstract
Web service technologies are becoming increasingly
important for integrating systems and services. There is
much activity and interest around standardization and
usage of web service technologies. The Unified Modeling
Language (UML) and the Model Driven Architecture
(MDA)™ provide a framework that can be applied to
web service development. This paper describes a model-
driven web service development process, where web
service descriptions are imported into UML models;
integrated into composite web services; and the new web
service descriptions are exported. The main contributions
of this paper are conversion rules between UML and web
services described by Web Service Description Language
(WSDL) documents and XML Schema.
1. Introduction
Web services are functional components, available
over the Internet, and described in the Web Service
Definition Language (WDSL) [4]. This paper1
investigates the use of UML to express the contents and
behavior of web services in a more understandable way
than WSDL.
UML modeling for automatic generation of CORBA
IDL, Java code, EJB etc. has been successfully tried out
(e.g. [10]). Model-driven approaches are also
recommended by the MDA initiative of the OMG [2].
When it comes to web services, several UML enthusiasts
have experimented with UML diagrams for automatic
generation of WDSL service descriptions [5, 7]. This

1 This work has been funded by the European Union
project IST-2001-37724, Adaptable and Composable E-
commerce and Geographic Information Services (ACE-
GIS)
paper questions the WSDL-dependency of current service
modeling approaches and investigates the usefulness of
WSDL-independent UML models for web service
specification. It raises the following two questions:
(a) Are WSDL-specific UML constructs necessary to
understand what the web service does? Or does pure
UML provide even better understanding?
(b) Are WSDL-specific UML constructs necessary for
forward and/or reverse engineering of web services? Or
can pure UML be used successfully for the same
conversions?
The first question is discussed in Section 2, and the
second in Section 3. The experiences with the conversion
rules developed and the conclusions of the paper are
given in Sections 4 and 5.
2. Modeling Web Services in UML
Before starting the argumentation, we need an
overview of the context in which UML models of web
services seem to be useful. In model-driven development
we use models to describe business concerns, user
requirements, activities, information structures,
components and component interactions of a system.
These models govern the system development in that they
can be transformed to program code. In the case of web
service development the models are transformed into the
Web Service Description Language. A number of web
services are now available and it therefore seems natural
to reuse existing web services and thus aim at creating
composite web services.
Figure 1 shows a UML activity diagram indicating the
steps of model-driven web services development of
composite web services. In the first step (Discover Web
Services) the developer uses a web-browser, a registry
client to search and discover candidate web services that
may be used in the composite service. The output of this
activity is a list of web service descriptions, represented
as WSDL documents. To follow the model-driven
philosophy the developer needs to import the necessary
web service descriptions into UML by a reverse
engineering transformation (Import Web Service
Proceedings of the 2004 IEEE International Conference on e-Technology, e-Commerce and e-Service (EEE’04)
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