=Paper=
{{Paper
|id=None
|storemode=property
|title=From Business Services to Web Services: an MDA Approach
|pdfUrl=https://ceur-ws.org/Vol-586/iStar10-paper06.pdf
|volume=Vol-586
|dblpUrl=https://dblp.org/rec/conf/istar/EstradaMMP10
}}
==From Business Services to Web Services: an MDA Approach==
https://ceur-ws.org/Vol-586/iStar10-paper06.pdf
From Business Services to Web Services: an MDA
Approach
Hugo Estrada 1, Itzel Morales-Ramírez 2, Alicia Martínez 1, Oscar Pastor 3
1
CENIDET, Cuernavaca, Mor. México
{hestrada, amartinez}@cenidet.edu.mx
2
Universidad Veracruzana, Xalapa, Ver. México
itmorales@uv.mx
3
Technical University of Valencia, Spain
opastor@dsic.upv.es
Abstract. At present, enterprises need sophisticated software applications to
sell and promote their products or services in order to maintain their leadership
in the business world. One of the most promising trends is the Web services
technology as the appropriate mechanism to implement e-business, which uses
Internet to replicate services offered by an enterprise. However, despite the
clear advantages of Web services, there are problems in determining the initial
functionalities required by them. Currently, Web services functionalities are not
obtained in a systematic manner from the organizational environment.
Therefore, it is complicated to ensure that Web services fit the business user’s
needs. In this paper we face this problem by defining a methodological
approach to generate Web services from organizational descriptions. The
Model-Driven Architecture has been used in this work in order to ensure the
systematic translation of modeling primitives of the organizational model into
their corresponding WSDL services descriptions.
Keywords: business service, Web service, Model-Driven Architecture.
1 Introduction
Internet has become an essential tool in current enterprises’ activities [1], where it has
been used as a successful strategy to guarantee their competitiveness in order to
maintain their leadership. In this context, e-business has been implemented as a
mechanism that allows the enterprises to offer their products and services remotely, so
they can expand their scope previously limited by the location. E-business approach
focuses on determining the processes needed by a company to offer their services
through the Web. In this context, the Web services are a key technology for an
effective operation of e-business systems.
Web services are very useful in the enterprise context because they allow
interoperability between software applications. The Web services can afford the
evolution of processes that use the same data while merely changing the
implementation. This flexibility feature allows diversity in “how” something is done.
31
Proceedings of the 4th International i* Workshop - iStar10
However, not all problems involved in developing Web services have been
properly solved. One of the main issues in defining Web services is the difficulty to
determine what should be the expected functionality of such services. This problem
arises from the following factors: 1) the current technology in Web service modeling
focuses on defining its functionality without considering, in a systematic manner, the
main needs of the organizational context; 2) the lack of reliable sources that allow the
designers to implement a Web service reflecting the business tasks as well as the
user’s requirements; 3) the need of some mechanisms to establish the correspondence
between the business functionalities and those which have been implemented in Web
services.
We consider the most important of the current difficulties to specify the correct
functionality of Web services to be the following: a) business models are not properly
adapted to support service-oriented specifications and the result is the incompatibility
between these models and those that implement the Web services; and b) there is a
lack of methodological approaches to automatically generate services from the
business’s features which results in this process often needing to be accomplished
manually. Therefore, we can conclude that Web services require the establishment of
a good specification of the processes that are involved in the enterprise context.
In this research work, a methodological approach is proposed to generate WSDL
(Web Services Description Language) descriptions, which are obtained from service-
oriented business models. The source model [3] is at a high level and deploys the
services offered by an enterprise to customers. It is important to point out that service-
oriented approach has been developed over the i* Framework by adding new rules
and properties to get an organizational vision of services. This is the reason why its
notation uses the concept of dependency to indicate that a service helps to satisfy the
goals of a user. Also the more detailed view of services is represented using an
extension of i* primitives.
As a contribution, this work established an approach of generation of services
where the business model is correctly adapted to the service technology, and the Web
services are obtained in a systematic way using the MDA (Model Driven
Architecture) approach [6].
2 Objectives of the research
The main objective of this work is to obtain the WSDL specifications of Web services
from service-oriented organizational models [3]. It is important to point out that
several research works exist which discuss the creation of Web services from
organizational models [4] [5] [8], however, the research work presented in this paper
represents the first approach that proposes the use of the MDA standards to translate
service-oriented business models into Web Service descriptions. It is also important to
comment that in most of the related works [4] [5] [8] [9] we found the following
issues: 1) the Web service modeling is not considered within the organizational
environment; 2) some of them have not applied the MDA approach; or 3) the works
have not carried out a generation of the WSDL specification.
32
From Business Services to Web Services: an MDA Approach
The proposed methodological approach consists of three phases which are
summarized below and depicted in Figure 1:
a) The MDA approach imposes a restriction to transform models; it consists in
achieving the transformation using models based on MOF (Meta-Object Facility)
specifications [7], and using well-defined models to ensure a systematic generation
when applying the transformation rules from a PIM (Platform Independent Model)
source model to a PSM (Platform Specific Model) destination model. In this phase we
have defined a metamodel for the business service model proposed in [3], the MOF-
Ecore specifications were applied in order to create this metamodel.
b) Once the metamodel was defined, the standard of the Object Management Group
(OMG), MOFScript, is used to establish the transformation rules M2T (Model to
Text), to allow the definition of transformations between a business environment and
the implementation of Web services.
c) Finally a software tool, called MOS Tool, uses the rules in MOFScript to generate
the WSDL documents (PSM). First, the business service model (PIM) is created and
used as a guide for designing the Web services functionalities. The service model is
designed with the structure of business service metamodel (a), and then the rules (b)
are applied to create the WSDL documents.
Fig. 1. Overview of the proposed approach
3 Scientific contributions
A service-oriented metamodel: One of the main contributions was the creation of an
e-business metamodel (see Fig.1) which was obtained by applying the MOF-Ecore
specifications [2] on the primitives of the service-oriented business model [3]. Table 1
shows the relationship among the modeling primitives, their attributes and the
attributes description. It was not simple to establish the same level of correspondence
between Web service and the service element of the business service model, due to
the high level of abstraction in the business model. To match the Web service with the
business elements, we analyzed the similar functionalities of them, and we found that
a Web service corresponds to the process element; it represents correctly the Web
33
Proceedings of the 4th International i* Workshop - iStar10
service while the service element represents the orchestration. The metamodel, called
MOS Ecore, being based on MOF, ensures the compatibility required to be stored in
MOF repositories and handled through the MOF tools. Using the model, the Web
services are created inside the organizational context, and *.mos files are generated.
Table 1. Description of e-business primitives.
Business Service e-business Attributes Attribute description
models [3] primitives
Global model, Aggregated Execution Participation order in business
composite service service order model
model Description Details of the Service’s
offered
Basic Execution Participation order in
service order orchestration
Description Service’s details offered
Process model Process Transaction Indicates if it will be deployed
as a Web service
Execution Participation order in
order orchestration
Description Process’s details about what is
done
Protocol model Task Transaction Indicates if it will be deployed
as an operation
Execution Participation order in
order orchestration
Type Resource’s type generated
Description Task’s details about the atom
activity
Resource Type Resource’s type to be used by
a task
Description Resource’s details about how
is used by a task
Business models to Web services transformation rules: Another contribution is the
definition of the transformation rules in MOFScript which are necessary in order to
obtain the mapping from a MOS model to the WSDL description of Web. The rules
take the *.mos files as input models to generate WSDL specifications as output.
Service modeling tool. MOS tool was developed using NetBeans IDE 6.5 as a
mechanism to validate the proposed approach. It has the following features: 1) it
allows for creating and opening service models; 2) it serializes the MOS model to
XML; 3) it stores the models as files with extension *.mos and; 4) it executes Eclipse
V3.3.2 to apply the transformation rules using the MOFScript plug-in. Once the
WSDL document is created, it just needs to be checked in well-formed XML syntax.
34
From Business Services to Web Services: an MDA Approach
The only property that needs to be changed is the address where the implementation is
located.
4 Conclusions
In this paper, a methodological approach is proposed to generate Web services from a
business service model. We propose that by using a service-oriented model at an
organizational level, it is possible to facilitate the work of defining Web services
under a methodological approach such as MDA.
5 Ongoing an future work
In future work, we will be dealing with the generation of complete functionality of the
Web service. We are currently working on methods to use the organizational
descriptions (business service models) to generate precisely the choreography and
orchestration of services, using the BPEL language. Another proposal for future work
is the extension of the MOS Ecore metamodel to integrate all the modeling stages
proposed by the business service architecture [3].
References
1. Bieberstein Norbert, Bose Sanjay, Walker Lance, Lynch Angela: Impact of service-oriented
architecture on enterprise systems, organizational structures, and individuals. IBM System
Journal, 691-708 (2005)
2. Budinsky Frank, Steinberg David, Merks Ed, Ellersick Raymond, Grose Timothy J.: Eclipse
Modeling Framework. Addison-Wesley (2003)
3. Estrada Esquivel Hugo: A service-oriented approach for the i* framework. PhD Thesis,
Valencia University of Technology, Valencia, Spain (2008)
4. Grønmo Roy, Skogan David, Solheim Ida, Oldevik Jon: Model-driven Web Service
Development. Idea Group Inc. International Journal of Web Services Research, Vol.1, No.
4, 1-13 (2004)
5. Lau Diana, Mylopoulos John: Designing Web Services with Tropos. In: Proceedings of the
IEEE International Conference on Web Services (ICSWS'04). San Diego, California, USA
(2004)
6. OMG: MDA Guide Version 1.0.1. Specification, Needham, MA, OMG (2003)
7. OMG: Meta-Object Facility (MOF) Specification Version 1.4. Needham, MA, OMG (2002)
8. Papazoglou Mike P., Yang Jian: Design Methodology for Web Services and Business
Processes. In: A. Buchmann et al. (eds.) TES 2002. LNCS, vol. 2444, pp. 54-64, 2002.
Springer, Heidelberg (2002)
9. Vara Juan M., De Castro Valeria, Marcos Esperanza: WSDL Automatic Generation from
UML Models in a MDA Framework. International Journal of Web Services Practices, Vol.
1, No. 1-2, pp. 1-12 (2005)
35