Bridging existing Web Modeling Languages to Model Complex Web- Applications

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Bridging existing Web Modeling
Languages to Model Complex Web
-

Applications

Mukesh Gupta, Deepika Sainani, Mahesh
Kumar Joshi

Reader, M.Tech Scholar

Swami Keshvanand Institute of Technology,
Management & Gramothan

, Jaipur

mukeshgupta@skit.ac.in ,

deepikasainani@gmail.com
,
mjoshi
293@gmail.com

ABSTRACT

The development of the World Wide
Web over the past years has sparked
innovation and challenged technicians all
over the world. We face a new, wide
spectrum of Web applications that go further
than th
e specification of the navigation map,
including aspects such as continuous website
evolution together with the existence of a
heterogeneous audience that implies that the
website design should cope with different
user’s needs, goals, preferences, and
capa
bilities. Moreover websites typically
serve large audience what can lead to
maintenance and usability problems.

Web Engineering, an emerging new
discipline, advocates a process and a
systematic approach to development of high
quality Web
-
based systems called Web
Modeling Languages. In this context Web
Design Methodologies appeared [ WebML
(Web Modelling Language),
WSDM
(Website Design Method), UWE(UML
-
Based Web Engineering), Hera, OO
-
H
(Object Oriented
-

Hypermedia), OO HDM
(Object Oriented
-

Hyper Media Design
Model), OO WS (Object Oriented Web
Services), WSML (Web Service Modelling
Language), W2000 (Web 2000), WAE

(Web Application Extension)], giving
solutions both for designers (e.g. design
support, help in determining consistent
structuring, easier maintenance) and for users
(e.g. better tailored content, easier
navigation).

Although we briefly survey the all
exi
sting approaches proposed to model Web
applications, these Web methods have some
limitations and drawback for complex Web
modelling. In this paper, we think a powerful
but yet simple mechanism to solve the
limitations of existing languages in this
environm
ent.

Dimensions of Web Modeling

In the last decade, the number and
complexity of websites and the amount of
information they offer is rapidly growing.
We face a new, wide spectrum of Web
applications that leads to new challenging
and demanding requirements

that go further
than the specification of the navigation map,
including aspects such as continuous website
evolution together with the existence of a
heterogeneous audience that implies that the
website design should cope with different
user’s needs, goal
s, preferences, and
capabilities. Moreover websites typically
serve large audience what can lead to
maintenance and usability problems.


S
urvey of Web modeling Languages

In this section we briefly survey the many
structured approaches proposed to model
c
omplex Web applications. Although they
share the same high
-
level goals, the different
proposals have some significant differences.

2.1 WebML

WebML

(Web Modeling Language) [Ceri et
al, 2002; Ceri

et al., 2000] is a visual
language for specifying the content structure
of a Web application and the organization
and presentation of contents in one or more
hypertexts. In WebML the following models
are defined:


Data Model:

The design process starts with the
specification of a data schema, expressing
the organization of the Web application
contents. The WebML Data Model adopts
the Entity
-
Relationship (E
-
R) primitives or
the UML class diagram.


Hypertext Model
:

The WebML
Hype
rtext Model
allows
describing how contents, previously
specified in the data schema, are published
into the application hypertext. The overall
structure of the hypertext is defined in terms
of pages, units and links, organized into
modularization construct
s called site views
and areas.

2.2 WSDM

WSDM

was initiated in 1998 by De
Troyer and Leune [De Troyer and Leune,
1998] and is one of the first Web site
design methods. It facilitates the
development of Web sites and Web
applications in a systematic way.
WSDM
has several important pillars, which
distinguishes it from other Web design
methods:


Audience Driven
:

WSDM takes as a
starting point the different users with
their different requirements and goals.
The audience of the site is categorized
into a hier
archy according these
requirements, and the navigation
structure of the site is based upon this
hierarchy.


Methodology
:

more than other design
methods, WSDM is a methodology. Next
to the necessary models and primitives to
model, at different levels of ab
straction,
the different concerns of a Web
application, WSDM also provides the
designer with a clear method on how to
construct these design models.


Conceptual design
:

WSDM makes a
distinction between the conceptual design
(task analysis, modeling data a
nd
functionality, and the conceptual navigation
schema) and the implementation design
(grouping information onto pages, layout and
presentation).


Implementation design
:

WSDM
makes a distinction between the
implementation design (grouping into pages,
layo
ut and presentation) and the actual
implementation (e.g. java servlets, php code,
html, XML, )


2.3 UWE

The UWE approach is an object oriented
approach which has as a distinguishing
feature its Unified Modeling
Language
compliance since UWE is defined in
the
form of a

UML profile an extension of the UML meta
-
model. UWE follows the principles of the
Unified Software Development Process
[Jacobson et al, 1999] and supports the
systematic development of Web applications
focusing on the specification of adaptiv
e
(personalized) applications. An extension of
ArgoUML known as ArgoUWE gives
support to the approach. The fundamentals of
this approach are a standard notation (UML
through all the models), the precise definition
of the method and the specification of
con
straints (with the OCL language) to
increase the precision of the models. The
separate modelling of Web application
concerns is a main feature of this approach.
Thus, different models are built for each
point of view: the content,the navigation
structure,
the business processes and the
presentation.

2.4 Hera

The Hera methodology [Houben et al, 2004]
is a model
-
driven methodology for designing
and developing Web Information Systems
(WISs). From the gathering of requirements
to the maintenance of the operatio
nal
application, most information system design
methodologies distinguish several phases in
the design process. The development of a
WIS is different in several aspects, and these
aspects are the central focus of the Hera
project. Like other WIS methodolog
ies, Hera
includes a phase in which the hypermedia
(Web) navigation is specified. Hera
considers navigation in connection to the
data intensivenature of the modern WIS in its
presentation generation
phase.

Before, Hera’s
integration and data retrieval
phas
e considers how to select and obtain the
data from the storage part of the application.
This includes transforming the data from
these sources into the format (syntax and
semantics) used in the application. Also, the
handling of the interaction from users
is
specified: querying, navigation, or
application
-
specific user interaction.

2.5 OO
-
H


The OO
-
H (Object
-
Oriented Hypermedia)
method is a generic model, based on the
object
-
oriented paradigm, that

provides the
designer with the semantics and notation
necessary for the development of Web
-
based
interfaces and its connection with previously
existing application logic modules.

OO
-
H defines a set of diagrams, techniques
and tools that shape a sound appr
oach to the
modeling of Web interfaces. The OO
-
H
proposal includes:

• Design process

• Pattern catalog

• Navigation access diagram (NAD)

• Two
-
fold presentation layer (abstract
presentation diagram and composite layout
diagram)

• CASE tool that supports an
d automates
to a certain extent the development process

2.6 OO
-
HDM


The Object
-
Oriented Hypermedia Design
Method (
OOHDM
) [Schwabe and Rossi,
1995; Schwabe and Rossi, 1998] and its
successor, the Semantic Hypermedia Design
Method (
SHDM
) [Schwabe and Moura,
2003; Schwabe et al. 2004]) allows the
concise specification and implementation of
hypermedia (Web) applications. This is
achieved based on various models describing
information (conceptual), navigation and
interface aspects of these applications, and
the
mapping of these models into running
applications, in various environments.

In OOHDM, a hypermedia application is
built in a five
-
step process (
Requirements
Gathering
,
Conceptual Design, Navigational
Design, Abstract Interface Design &
implementation phase
) supporting an
incremental or prototype process model.
Each step focuses on a particular design
concern, and an object
-
oriented model is
built.

2.7 OOWS


Some Web Engineering methods (OOHDM
and WebML
) are trying to introduce web
services into their web
conceptual modelling
approaches. However these approaches do
not give support to the design and develop of
Web service

The OOWS approach introduces a model
driven approach to develop web application.

The OOWS method integrates navigational
design with a cl
assical OO conceptual
modelling providing systematic code
generation (OO
-
Method). This work is an
initial effort to introduce SOA and the Web
services technology in theOOWS method.

Our proposal defines a methodological guide
that allows us to identify a s
et of functional
groups that define public and coarse grained
services in amulti
-
tier SOA. This is done by
taking the conceptual models that the OOWS
method provides and providing a model
driven strategy to systematically obtain the
functional groups (web
services) by
extracting all the useful knowledge that the
models include.


2.8 WSML


WSML distinguishes between conceptual and
logical modeling

in order to support users who are
not familiar with formal logic, while not restricting
the expressive power of the language for the expert
user. In this context, the Web Service Modeling
Ontology WSMO provides a conceptual model for
the description of va
rious aspects of Services
towards such Semantic Web Services (SWS). In
particular, WSMO distinguishes four top
-
level
elements:

Ontologies

Ontologies provide formal and
explicit specications of the vocabularies used by
the other modeling elements. Such for
mal
speci_cations enable automated processing of
WSMO descriptions and provide background
knowledge for Goal and Web Service
descriptions.

Goals

Goals describe the functionality and
interaction style from the requester perspective.

Web Service descriptions

Web Service
descriptions specify the functionality and the
means of interaction provided by the Web
Service.

Mediators
Mediators connect different WSMO
elements and resolve heterogeneity in data
representation, interaction style and business
processes.

2.9 W2000

W2000
is a complete notation for modeling
complex Web applications.

It borrows concepts
from different domains and integrates them in a
homogenous

solution. W2000 originates from
HDM (Hypertext Design Model
),

that is, from
hypermedia and data
-
cen
tric Web applications,
but also borrows

from UML

(Unified Modeling
Language
) to support the conception

of business
processes. W2000 allows the designer to model
all the aspects of

Web applications, from Web
pages to business transactions, in a coherent an
d

integrated way. It also
adopts a model
-
driven
approac

to allow designers

to refine their models
incrementally and move smoothly from
specification to

design.

This chapter introduces the main concepts of
W2000 through its metamodel.

According to the
OMG j
argon, the meta
-
model defines the
modeling

elements of a notation without
concentrating on their concrete syntax.



2.10 WAE

WAE

is an exception, because WAE itself is
not a web site design method. It’s added to this
overview because WAE provides an extension,
or profile to UML similar as in UWE.
Although WAE provides us a way to represent
Web pages and other architecturally signif
icant
elements in UML it does not provide a
separation between navigation and presentation
aspects. Neither does it provide a way to think
about the way web eng
ineering should be
done. On
a roadmap and some
recommendation are defined but these can’t be
see
n as a design method.

All the aforementioned approaches
emphasize the need for an incremental and
interactive development process, and all are
essentially based on the information
-
navigation paradigm. These approaches
mainly differ in the complexity and ac
curacy
of proposed modeling primitives, in their
support to business processes, and in their
support to the user context (e.g., role, device,
localization).

CONCLUSIONS

Although space limitations do not allow us to
deeply explain some key features for all
the
web modeling languages, like the support to
application families and transformation rules,
tools used. So we have presented the wide
introduction to modeling languages for Web
applications
.

It is commonly shown that current Web

Oriented languages are
too target
-
environment dependent and, therefore, lack
the flexibility needed for the development of
complex Web applications. Well
-
defined
software development processes are
necessary in order for the community of
software engineers to design Web
-
based
app
lications in a systematic way and thus
avoid the risks of failure involved in ad hoc
development processes. Our purpose has
been to address these problems from all the
web modeling languages.

As well all the
existing Web methods
discussed in this paper do

not intend to be yet
another method for Web modeling. Also, we
think a powerful but yet simple mechanism
to solve the limitations of existing languages
in this environment

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