* This monograph will be also published in Spanish (full version printed; summary, abstracts, and some
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Informática) at <http://www.ati.es/novatica/>.
UPGRADE is the European Journal for the
Informatics Professional, published bimonthly
at <http://www.upgrade-cepis.org/>
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UPGRADE monographs are also published in Spanish (full version
printed; summary, abstracts and some articles online) by Novática
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published by Novática and INFORMATIK/INFORMATIQUE, bi-
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Editorial TeamEditorial Team
Chief Editor: Llorenç Pagés-Casas
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ISSN 1684-5285
Monograph of next issue (June 2008)
"Next Generation
Technology-Enhanced Learning"
(The full schedule of UPGRADE is available at our website)
Vol. IX, issue No. 2, April 2008
2 Editorial
New UPENET Partners — Niko Schlamberger (President of CEPIS)
2 From the Chief Editor’s Desk
Welcome to our Deputy Chief Editor — Llorenç Pagés-Casas
(Chief Editor of UPGRADE)
4 Presentation. MDA® at the Age of Seven: Past, Present and Future
— Jean Bézivin, Antonio Vallecillo-Moreno, Jesús García-Molina,
and Gustavo Rossi
7 A Brief History of MDA — Andrew Watson
12 MDA Manifestations — Bran Selic
17 The Domain-Specific IDE — Steve Cook and Stuart Kent
22 Model Intelligence: an Approach to Modeling Guidance — Jules
White, Douglas C. Schmidt, Andrey Nechypurenko, and Egon Wuchner
29 Model Differences in the Eclipse Modelling Framework — Cédric
Brun and Alfonso Pierantonio
35 Model-Driven Architecture® at Eclipse — Richard C. Gronback
and Ed Merks
40 Model-Driven Web Engineering — Nora Koch, Santiago Meliá-
Beigbeder, Nathalie Moreno-Vergara, Vicente Pelechano-Ferragud,
Fernando Sánchez-Figueroa, and Juan-Manuel Vara-Mesa
46 From Informatik Spektrum (GI, Germany, and SI, Switzerland)
High Performance Computing
The TOP500 Project: Looking Back over 15 Years of Supercomputing
— Hans Werner Meuer
62 From Mondo Digitale (AICA, Italy)
Project Management
Critical Factors in IT Projects — Marco Sampietro
68 CEPIS Projects
Selected CEPIS News — Fiona Fanning
CEPIS NEWS
UPENET (UPGRADE European NETwork)
Monograph: Model-Driven Software Development
(published jointly with Novática*)
Guest Editors: Jean Bézivin, Antonio Vallecillo-Moreno, Jesús García-Molina,
and Gustavo Rossi

40 UPGRADE Vol. IX, No. 2, April 2008 © Novática
Model-Driven Software Development
Keywords: CASE Tools, Interoperability, Metamodels,
Model Driven Architecture (MDA), Model Driven Devel-
opment (MDD), Model Transformations, Web Engineering.
1 Introduction
Since 2001 the Model-Driven Architecture (MDA) ini-
tiative has been applied to many application domains show-
ing that, in general, it works better in those domains domi-
nated by functional requirements, with well structured mod-
els, precise separation of concerns and standard platforms.
Web Engineering, specifically, has proved to be an applica-
tion domain where MDA has brought significant benefits.
In particular, MDA allows successfully addressing
interoperability, model evolution and adaptation problems
of Web systems, as emerging new platforms and changes in
technologies constantly happen in this area.
In this sense, we have seen how many Web Engineering
approaches are shifting to becoming "MDA compliant",
which has resulted in some major changes in their nota-
tions, processes and tools. In particular, some of these ap-
proaches have had to: (a) redesign their Web modelling lan-
guages using meta-modelling techniques, rather focusing
on notational aspects of the languages being used; (b) reor-
ganize their original set of models in a modular and plat-
form independent manner; (c) reformulate their develop-
ment processes in terms of model transformations and model
merges; and (d) incorporate and adopt standards that sup-
port the realization of the MDA initiative such as UML®
(Unified Modelling Language), MOF (Meta-Object Facil-
ity), XMI (XML Metadata Interchange), or QVT (Query/
View/Transformations)1 .
However, despite all these challenges, the benefits of
the adoption of Model-Driven Development (MDD) and
MDA ideas and techniques, to Web Engineering has far
outweighed its costs. MDA has provided the opportunity to
inject good software engineering practices into the Web
applications domain; and has allowed successful bridging
Model-Driven Web Engineering
Nora Koch, Santiago Meliá-Beigbeder, Nathalie Moreno-Vergara, Vicente Pelechano-Ferragud,
Fernando Sánchez-Figueroa, and Juan-Manuel Vara-Mesa
The continuing emergence of new platforms and technologies make Web applications resemble more and more complex
desktop applications. Therefore, the tasks of designing, implementing and adapting the Web applications are becoming a
more time-consuming and error-prone issue. In the Web Engineering context, Model-Driven Development (MDD) and
Model-Driven Architecture (MDA) principles are being used to successfully address the construction, evolution and adap-
tation of Web applications. In this article we show how the Model-Driven Web Engineering (MDWE) discipline has arisen
and how MDD/MDA principles are applied in the Web Domain to define models and metamodels, to specify model trans-
formations, to manage interoperability issues and to build tools that support the development process.
Authors
Nora Koch has been a research assistant at the Ludwig-
Maximilians-Universität (LMU) of Munich (Germany) since
1995 and has worked at F.A.S.T. Applied Software Technology
GmbH as consultant and project manager since 1998. She
received her Ph.D. in Computer Science from the LMU in 2000.
Nora is leader of the Web Engineering Group at the LMU,
responsible for the development of the UWE methodology. Her
main research interests focus on methods for the development
of Web applications, personalised Web systems and model-driven
engineering. Nora organised the 4th International Conference
on Web Engineering (ICWE 2004) in Munich, two editions of
the Model-Driven Web Engineering Workshop (MDWE 2005
and MDWE 2007) and is a founder of the network MDWEnet.
She is a member of the IEEE and the German Society of
Informatics. Nora has published more than 70 publications.
<kochn@pst.ifi.lmu.de>.
Santiago Meliá-Beigbeder is Assistant Professor at the
Department of Languages and Information Systems at the
University of Alicante (Spain), where he is the director of a
postgraduate Master in Software Engineering. Also, he is a
member of the IWAD research group in the same University.
His research interest includes Model-Driven Development, Web
Engineering Methodologies, Automatic Code Generation
Techniques and Web Software Architecture, all of which were
part of his Ph.D. received at the University of Alicante in 2007.
He has published in prestigious journals such as the European
Journal of Information Systems, Journal of Web Engineering,
Revue d’Interaction Homme-Machine and Lecture Notes in
Computer Science, and at conferences (OOPSLA, EC-MDA,
ER, EC-Web, ICWE, CADUI, etc.). He regularly serves on the
Program Committees of several international conferences and
workshops. <santi@dlsi.ua.es>.
Nathalie Moreno-Vergara is Assistant Professor in the
Department of Computer Science of the University of Málaga
(Spain) where she received her MSc. and is completing a Ph.D.
in Computer Science. Her research interest is mainly oriented
towards model-driven development and, in particular, she is
interested in investigating conceptual modeling methodologies,
business process modeling, model transformation languages and
code-generation techniques in the Web applications context. Her1 OMG. <http://www.omg.org>

UPGRADE Vol. IX, No. 2, April 2008 41© Novática
Model-Driven Software Development
most significant publications can be found in relevant journals
(the European Journal of Information Systems, the Journal of
the American Society for Information Science and Technology
or the ET Software), book chapters in Springer Verlag and well-
known international conferences such as ICWE, DEXA,
MODELs, ICSE, etc. She usually participates as part of program
committees and reviewer of conferences and workshops in her
research area. <vergara@lcc.uma.es>.
Vicente Pelechado-Ferragud is Associate Professor in the
Department of Information Systems and Computation (DISC)
at the Valencia University of Technology (Spain). His research
interests are web engineering, conceptual modelling,
requirements engineering, software patterns, web services,
ambient intelligence, business process modeling and model
driven development. He received his Ph.D. from the Valencia
University of Technology in 2001. He is currently teaching soft-
ware engineering, design and implementation of web services,
design patterns, and model driven development and code
generation in the Valencia University of Technology. He is a
member of the OO-Method Research Group at the DISC. He
has published in several well-known scientific journals
(Information Systems, Data & Knowledge Engineering,
Information and Software Technology, Internacional Journal of
Web Engineering and Technology, etc.), book chapters in
Springer, IDEA, M. Sharpe and international conferences (ER,
CAiSE, WWW, ICWE, EC-WEB, WISE, AH, ICSOC, DEXA,
etc.). He has been a member of Scientific and Organizing
Committees of well-known International Conferences and
Workshops (CAiSE, ER, ICWE, ICEIS, ACM MT and IADIS).
<pele@dsic.upv.es>.
Fernando Sánchez-Figueroa is a professor in the Department
of Computer Science at University of Extremadura (Spain),
where he teaches Concurrent Programming and Design Patterns.
Sánchez has a MSc. in computer science from the University of
Sevilla (Spain) and a Ph.D. in computer science from the
University of Extremadura. His research focuses on Web
Engineering, specifically on Rich Internet Applications, Web
Acessibility and Model Driven Web Engineering. He has been
Vice-rector of ICT at the University of Extremadura for four
years. Currently he holds a “Software Engineering” chair
sponsored by INSA-IBM. < fernando@unex.es>.
Juan-Manuel Vara-Mesa obtained his BSc. and MSc. in
Computer Science Engineering at the Universidad Rey Juan
Carlos (Madrid, Spain), where he did the Doctoral Courses on
the Computer Science and Mathematical Modeling Program.
Currently he works as assistant professor in the department of
Informatics Languages and Systems II of the Universidad Rey
Juan Carlos and he is a member of the Kybele Research Group
where he is doing his Ph.D. thesis focused on Model-Driven
Engineering for the development of Web Information Systems.
He is co-author of several books and book chapters, as well as
several publications at national and international events and
journals, and he has participated on several regional, national
and European research projects. <juanmanuel.vara@urjc.es>.
of the previously existing gap between the high level de-
sign models and concepts and the low-level Web imple-
mentation code (Preciado et al [1]). This has led to a disci-
pline within the Web Engineering called Model-Driven Web-
Engineering (MDWE) that focuses, among others, on the
interoperability of the currently existing methodologies for
the development of Web applications. Worthy of mention is
the MDWEnet2 initiative started by a group of European
researchers working on MDWE, with the objective of im-
proving the interoperability of MDWE approaches and tools
in order to widen their scope and provide better tools and
methods to the industry.
The adoption of MDD/MDA by the Web Engineering
community is not free from problems and limitations. In
this article, we shall give a critical overview of the state of
the art in MDA-based Web Engineering as currently per-
ceived by some of the groups that actively work on it. Not
only the efforts and results already achieved will be de-
scribed, but also the challenges, threats and weaknesses of
this approach will be identified based on our experiences
and developed systems, with the aim of helping MDA to
evolve towards a more mature and successful development
approach for Web systems.
The paper is structured as follows. Section 2 describes
the role achieved by models and meta-models in the ab-
straction and design process of current Web applications as
a consequence of the MDA goal of automatically generat-
ing implementations from models. In this context, Section
3 illustrates the way in which model transformations are
used within the development process. A brief report on tools
that support MDD/MDA principles in the Web domain is
given in Section 4. Section 5 shows how the Web Engineer-
ing community has addressed the difficult problems of
interoperability using the MDA concepts and mechanisms.
Finally, Section 6 points out current strengths, weaknesses
and major challenges that could considerably improve the
efficiency of using MDA in the Web context.
2 Models and Metamodels in the Web Domain
MDA is based on the construction and transformation
of models which represent a computational independent
viewpoint (CIM), a platform independent viewpoint (PIM)
or a platform specific viewpoint (PSM). During recent years,
the Web engineering community has proposed several meth-
ods for modelling Web applications that mainly focus on
the construction of PIMs. Web Engineering methods, Rossi
et al. [2] like Hera, OOHDM, OOWS, UWE, WebML,
WSDM, and methods such as MIDAS [3], OO-H and
WebSA (for both see Meliá et al [4]) propose building simi-
lar types of models but using different graphical notation
for the representation of these models. Most of them use a
proprietary notation; some combine the use of the Unified
Modeling Language (UML) with their own notation, and
only UWE and WebSA use UML 2.0 for all its models. UWE
uses plain UML as far as possible and defines for the Web
domain features a UML profile following the extension
mechanisms provided by UML. As a result, UWE is a UML2 MDWEnet. <http://www.pst.ifi.lmu.de/projekte/mdwenet/>.

42 UPGRADE Vol. IX, No. 2, April 2008 © Novática
Model-Driven Software Development
compliant Web domain specific language. There is a clear
tendency to the use of UML by other methods as well, mainly
due to the advantages provided in the use of CASE tools
and meta-modelling for model-driven approaches.
A main characteristic shared by all these Web engineer-
ing approaches is the separation of concerns. This charac-
teristic allows building different models to address a vari-
ety of concerns relevant in the Web domain like content of
the Web application, hypertext structure, presentation as-
pects, adaptivity (in particular personalisation and context-
awareness) and Web architectural issues. Models are merged
based on integration mechanisms either implemented in
proprietary tools or by the application of general rules de-
fined in model transformation languages. In addition,
MDWE approaches follow the MDA principles creating
CIMs such as the requirements models built by WebRE [5]
and OOWS; building PIMs for navigation, presentation and
business process specification (almost all methods); build-
ing PIMs for architectural models (WEI and WebSA); and
obtaining PSMs or transforming into code for specific plat-
forms such as Java EE, Struts, Spring and .NET. The gen-
eral objective is that in the development process the crea-
tion of models that take into account technological aspects
is postponed as long as possible. The main advantage is to
be able to react efficiently and with low costs to technology
changes.
The entities used in all these Web specific models, and
the relationships between entities can be also represented
as a model, a so-called metamodel, which is needed for the
specification of the model transformations. The first
metamodel in the Web domain was presented for the UWE
approach at the 3rd International Conference on Web Engi-
neering (ICWE 2003) [6]; other methods defined then their
metamodel; recently Moreno and Vallecillo [7] proposed a
common reference metamodel called Web Engineering
Interoperability (WEI), which is described as a MOF
metamodel. WEI also defines lightweight extensions of
UML, i.e., UML profiles, for representing the specific syn-
tax for each of its metamodels.
3 Model Transformations for Generating Web Ap-
plications
As the MDA framework suggests, the transformations
could be applied to establish a traceable development proc-
ess from abstract models (CIM or PIM) to the platform de-
pendent models (PSM) or directly to the implementation.
Thus, many Web engineering approaches have defined trans-
formations to obtain some parts or the entire implementa-
tion of a Web application. As it is well known, a domain-
specific strategy such as the Web domain, allows signifi-
cant parts of the implementation to be generated automati-
cally and to reduce the development effort [8]. Several Web
methods have taken advantage of this aspect by developing
commercial CASE tools as presented in the next section.
These CASE tools use code generation techniques to ob-
tain Web applications from a reduced set of conceptual or
design models. Within the model transformations scope we
can distinguish between model-to-model transformations
and model-to-code transformations. Currently, most Web
methods are starting to use model transformations to ex-
tend or to implement CASE tools in order to take advan-
tage of the opportunities which transformation languages
can provide.
Next, we present how the different Web methods have
applied model-to-model and model-to-text transformations
to produce Web applications.
3.1 Model-to-Model Transformations
There are two types of model-to-model transformations:
(1) vertical transformations that convert models from higher
into lower level of abstraction and (2) horizontal transfor-
mations which describe mappings between models of the
same level of abstraction.
Historically, in the Web domain, most cases of vertical
transformations have been developed using using tool-spe-
cific proprietary languages. More recently though, Web
approaches such as UWE [9], OOWS [10], WebSA [4] and
MIDAS [3] have formalized all or part of their develop-
ment process using model-to-model transformations lan-
guages such as QVT, ATL or AGG. In some cases, these
model-to-model transformations are defined as merge
mechanisms to introduce new concepts like architectural
styles (WebSA), user requirements (WebRE [5] and OOWS
Requirements Analysis [10]) and quality measures [11]. In
other cases, they have been established to formalize the
mappings from the original process (UWE [12]).
The horizontal transformations have been applied in the
Web domain to maintain the consistency of the model speci-
fications, checking that the different models do not impose
contradictory requirements on the elements they share [7].
However, due to the novelty of these models, there is a lack
of maturity in their current standards and tools. Therefore,
some of the properties of these transformations (reusabil-
ity, easy of use and a reduced maintainability) have not been
tackled yet. Furthermore, there is no Web Engineering com-
mercial CASE tool available that is completely based on
model-to-model transformations.
3.2 Model-to-Code Transformations
The Web engineering community has extensive experi-
ence in model-to-text transformations or code generation.
Approaches such as WebML, OOH, OO-Method/OOWS
have been generating Web applications for almost ten years
now. In some cases, code generation is realized using gen-
eral-purpose languages (C++, XSLT, Java or Python) which
do not cover some desirable requirements for the model-to-
text transformations. Recently, an OMG standard Model-
to-Text Request-For-Proposal has established the proper
characteristics of the model-to-text languages (e.g. Round-
Trip engineering) and some proposals such as Xpand and
MOFScript have been adapted to it with mixed success.
Recently, OOWS and WebSA have used MOFScript and
Xpand in the implementation of their code generators in
order to benefit from its properties.

UPGRADE Vol. IX, No. 2, April 2008 43© Novática
Model-Driven Software Development
4 CASE Tools supporting MDWE
In this section we give a brief overview of the existing
CASE tools supporting MDWE proposals and we make a
short review of the main problems and challenges to be tack-
led in this field. First of all, it should be noticed that we
make a distinction between UML based and non-UML based
tools.
On the one hand, we consider those CASE tools devel-
oped to work with domain specific languages that extend
the UML standard (UML profiles). The most relevant CASE
tool that falls in this category is ArgoUWE [13]. Initially,
ArgoUWE was developed to extend the open-source tool
ArgoUML by adding features for modelling content, navi-
gation, and presentation structures. Later on, features were
added to model the business logic and the behaviour of
workflow-driven Web applications and to detect inconsist-
encies in UWE models based on the UWE metamodel and
its OCL well-formed rules [13]. Currently the main prob-
lem of this approach is that ArgoUML and therefore
ArgoUWE does not support UML 2.0. WebTE [14] is a UML
tool that supports XMI and allows introduction of the OO-
H and WebSA models and transformations into a transfor-
mation engine which executes them and produces a Java
EE Web application. Currently there exists other solutions
based on the use of UML, like the AriadneTool [15], the
DaVinci framework [16], MIDAS-CASE [17] or
VisualWade [18], but they either offer just some limited
functionalities or have been closed.
On the other hand, we consider those tools developed to
work with languages for Web applications modelling and
deployment defined by means of MOF-based metamodels.
The tools in this group may be considered not fully "MDA
conformant", in the sense that they are not UML-based tools.
Currently the most representative of these is WebRatio [19].
WebRatio is a commercial tool developed for giving sup-
port to the WebML method that is focused on the develop-
ment of data-intensive applications. With WebRatio, the
business objects are modelled using the UML or E/R stand-
ards while the front-end is modelled using WebML. Then,
the entire application for the Java EE architectures and SQL/
XML data sources is automatically generated from those
models. There are also more recent non-UML CASE tools,
like M2DAT [3] or the OOWS Suite [20], but they are still
under development.
When talking about CASE tool support it should be noted
that the proliferation of technologies and tools for develop-
ing "your own" MDD tools is facilitating the adoption and
implementation of MDA principles and techniques. Many
software companies and research groups are considering
the development of their own CASE tool for supporting
their own MDWE method (following the MDA, Software
Factories, Product Lines, Generative Programming of what-
ever other more specific model driven proposal). This way,
technology is playing a key role in the distinction between
UML based and non-UML based tools: the facilities pro-
vided in the context of the Eclipse Modelling Project (EMP)
and other DSL frameworks, like the Generic Modelling
Environment (GME) or the DSL Tools, have shifted the fo-
cus from UML-based approaches to MOF-based ones.
Special attention has to be paid to the EMP. The quan-
tity and quality of the MDD facilities provided in the con-
text of this project (a common modelling framework like
EMF, meta-editors like GMF, transformation engines like
ATL or VIATRA, code generators like MOFScript) has given
rise to a new generation of Eclipse tools. As a consequence,
more and more MDWE proposals are developing their tools
as Eclipse plug-ins, like the OOWS suite and M2DAT, or at
least, upgrading or re-defining them to be "Eclipse compli-
ant", like WebRatio [21].
However, there is still a lot of work to do. A very com-
mon problem, clearly stated by Moreno and Vallecillo [2],
is that the mapping rules are typically hard-coded in the
CASE tool (e.g. this is the case of ArgoUWE and WebRatio).
This fact results in a gap between the design of the Web
application and the final implementation. According to MDA
principles, these rules should be defined at a more abstract
level, using the QVT standard. Although some proposals
have already tackled this task (see [13] for UWE, [4] for
WebSA and [7] for WEI), these improvements have still to
be integrated in the corresponding CASE tools. The lack of
a reference implementation for QVT (which has led to non-
complete QVT parsers for a subset of this language [7])
complicates this integration. Another problem is
interoperability, in this sense, the use of weaving models to
automate model migration is becoming widely accepted.
Vara et al [22] shows how to apply this approach in a real
industrial environment. Such an approach is being studied
as a way to automate tools interoperability. Finally, the reader
should notice that even though MDD is a widely accepted
approach, MDWE is still relatively new: all the tools listed
in this section are academic proposals. So, we can conclude
that the most outstanding challenge for the developers of
MDWE CASE tools is to take their tools from academic to
industrial environments.
5 Interoperability Issues in MDWE
As stated in previous sections, current model MDWE
approaches provide a set of methods and supporting tools
for a systematic design and development of Web applica-
tions. However, these proposals have some limitations, es-
pecially for exchanging models or representing further
modelling concerns, such as architectural styles, technol-
ogy independence, or distribution. A possible solution to
these issues is providing interoperability among MDWE
proposals, enabling them to complement each other.
Interoperability is at the heart of MDA at different levels:
models and metamodels, transformations and tools.
Regarding models and metamodels, there exist three
possibilities for achieving this interoperability: a) obtain-
ing a unified method based on the strengths of the different
methods; b) obtaining bridges for interoperability between
the individual models and tools and c) obtaining a common
metamodel. All these possibilities have their own benefits
and disadvantages. Currently there are two projects in

44 UPGRADE Vol. IX, No. 2, April 2008 © Novática
Model-Driven Software Development
progress regarding options b) and c). In [23] Wimmer et al.,
presented a methodology based on MDA for making
interoperable three Web modelling approaches (WebML,
OO-H and UWE). They used the Ecore implementation of
the MOF standard for the definition of the three metamodels.
ATL is used as model transformation language to imple-
ment the transformation rules and an ATL engine executes
the transformation. The next step for them is defining a com-
mon metamodel for Web Modeling. Another promising ap-
proach is WEI [7], a model-based framework for building
Web applications that, among other goals, tries to provide a
common framework (and metamodel) in which current pro-
posals could be integrated and formulated in terms of the
MDA principles. WEI can be instantiated both to build Web
applications from scratch, and to build Web applications
based on existing models (including those defined using
other methodologies, e.g., UWE, WebML or OO-H).
Regarding transformations, we find a problem due to
each approach using its own script language that is incom-
patible with other languages and tools that users often use.
In this sense, QVT is not being used as thought by the OMG
as stated in the previous section.
Regarding tools interoperability, despite the efforts of
the OMG, the XMI standard has proven to be unsuccessful,
especially when working with UML profiles. Until that hap-
pens it seems more convenient to take advantage of model-
to-model transformations to achieve CASE tools
interoperability, whether or not they are UML based tools.
6 Future Challenges
MDWE methods are evolving to be properly adapted to
the continuous evolution of Web system requirements and
technology. In the last few years a new type of Web appli-
cations, known as Web 2.0 has emerged. These applications
let people collaborate and share information online.
Murugesan [2] says the People-Centric Web and the Read/
Write Web, offers smart user interfaces and built-in facili-
ties for users to generate and edit content presented on the
Web and thereby enrich the content base.
Service Oriented applications and the Web 2.0 are pro-
viding a clear infrastructure to integrate multiple software
services under a rich user interface. AJAX-based (Asyn-
chronous Javascript and XML) Rich Client Applications or
RIAs, Service Mashups, REST or XML Web Services al-
low integrating current Web applications with third party
services, portals, and with legacy systems. RIAs are chang-
ing the browser from a static request-response interface to
a dynamic, asynchronous interface. RIAs promise a richer
user experience and a set of benefits that affect Web Engi-
neering methods [24].
The wide adoption of mobile devices allows users to
access the Web using handheld devices (pocket PCs, PDAs,
smartphones, etc). Mobile Web applications offer some ad-
ditional features compared to traditional desktop Web apps
such as location-aware services, context-aware capabilities
and personalization. We are not forgetting that Web appli-
cations development is a complex task that also needs to
take into account many different aspects and non functional
requirements such as scalability, reliability, availability,
evolution and maintainability, usability, security, accessi-
bility, mobility, localization, personalization, adaptivity, etc.
Web Usability is one of the most relevant quality fac-
tors that should be taken into account by current and future
model driven Web engineering methods. Usability should
be integrated in each step of the software development
method in a mandatory way, because generated Web apps
should meet the diverse expectations and needs of many
types of users, including able and disabled users, with dif-
ferent skills. The continuing appearance of new technolo-
gies like RIAs and the Mobile Devices does not guarantee
that current design guidelines and usability tests will work
for those new approaches to assure a better user experi-
ence.
However, MDA is still a relatively young approach and
there are some issues around the MDA-based software de-
velopment not yet sufficiently clarified. In particular, MDA
is originally intended for new developments and it is not
clear how MDA handles the production of releases, patches
or updates, an important part of the ongoing maintenance
of Web applications. Regarding non-functional require-
ments, MDA deals well with functional properties but it is
less capable of dealing with non-functional requirements.
In this sense, there is a debate about whether the specifica-
tion of non-functional requirements is within the scope of
MDA. In summary, while the principles underlying MDA
are sound, there remain issues that must be solved for MDA
to realize its full potential, particularly in the Web applica-
tions domain.
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