[AI] Tech dose of the day: WebML

vishnu ramchandani vishnuhappy at yahoo.com
Mon Feb 25 04:08:41 EST 2008


WebML
contributor : Baskar P (from MphasiS Software
Services)
What is WebML?
WebML (Web Modeling Language) is a visual notation for
designing complex data-intensive Web applications. It
provides graphical, yet formal, specifications,
embodied in a complete design process, which can be
assisted by visual design tools, like WebRatio.
WebML in a nutshell:
WebML provides graphical, yet formal, specifications,
embodied in a complete design process, which can be
assisted by visual design tools. The main objectives
of the WebML design process are:
(a) expressing the structure of a Web application with
a high-level description, which can be used for
querying, evolution, and maintenance
(b) providing multiple views of the same content
(c) separating the information content from its
composition into pages, navigation, and presentation,
which can be defined and evolved independently
(d) storing the meta-information collected during the
design process within a repository, which can be used
during the lifetime of the application for dynamically
generating Web pages
(e) modelling users and communities explicitly in the
repository, to permit the specification of
personalization policies and one-to-one applications;

(f) enabling the specification of data manipulation
operations for updating the site content or
interacting with arbitrary external services.
WebML models:
Designing a data-intensive Web site amounts to
specifying its characteristics in terms of various
orthogonal abstractions, each captured by a distinct
model.
The structure, composition, navigation, and
presentation models enable the description of
read-only web sites. They can be extended to cope with
the specification of content management and
integration with external services, through the
addition of operations, which can be defined and added
to the hypertext model. They are invoked as a side
effect of navigation and permit one to specify
commonly found interaction patterns as data entry,
personal data management, and shopping carts.
WebML concepts:
Models:-
•        Structure: data organization

•        Derivation: redundant data definition

•        Composition: definition of site pages as set
of subpages and elementary publishing units 

•        Navigation: definition of links between pages
and between units

•        Presentation: positioning of the units in the
page and definition of graphical appearance.
Site = Structure + Composition + Navigation +
Presentation   
Designing and maintaining Web applications is one of
the major challenges for the software industry of the
year 2000. Web Modeling Language (WebML), a notation
for specifying complex Web sites at the conceptual
level. WebML enables the high-level description of a
Web site under distinct orthogonal dimensions:
its data content (structural model), the pages that
compose it (composition model), the topology of links
between pages (navigation model), the layout and
graphic requirements for page rendering (presentation
model), and the customization features for one-to-one
content delivery (personalization model). All the
concepts of WebML are associated with a graphic
notation and a textual XML syntax. WebML
specifications are independent of both the client-side
language used for delivering the application to users,
and of the server-side platform used to bind data to
pages, but they can be effectively used to produce a
site implementation in a specific technological
setting. WebML guarantees a model-driven approach to
Web site development, which is a key factor for
defining a novel generation of CASE tools for the
construction of complex sites, supporting advanced
features like multi-device access, personalization,
and evolution management.
Further References 
Webml.org: 
http://www.webml.org/webml/page1.do


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