Page 191 - DCAP312_WEB_TECHNOLOGIES_II

Unit 9: The Database Model

subclassResponsibility stating that subclasses have the responsibility to define the method. When Notes
such a method is executed an exception is raised.

Method
aMethodDeclaredAbstract
“This is the responsibility of my subclasses to define this method”

self subclassResponsibility
Note that nothing prevents you to create instance of the class having abstract methods. This
will work until an abstract method will be invoked.

9.7 Creating the User Interface

Traditional application development involves the propose of data model/ERD representation,
develop the database, implement the industry layer, and finally the presentation layer. Some
advanced methodologies like RAD, let developers to develop their applications faster by facilitate
advanced and special tools. Another standard shift in application development seems happening
based on developing smarter components at different layers of software. Consequently, we can
expect faster and easier application design/development. This process focuses on the higher
level of development or the user interface design. To accomplish the task, we need a set of tools
to support this methodology. In other words, smart components would develop the back end
of the applications from the GUI, by setting all necessary constraints, validation, business rules
and other components. We call the proposed method “User Interface Oriented Application
Development, UIOAD”. Previous related works based on similar concepts have been brain-
stormed and user interface driven system design has been proposed. But in this approach, since
the user interface (UI) forms are essential in capturing data requirements, UI prototype can be
used by the developer as a source for developing the classes and objects. The existence of a
field on a dialog, a web page, or a report means that the data must either be an attribute of an
object, the result of some operation on an object or series of objects, or be calculated from some
other object(s) attributes. When the same data exists within different objects on the same user
interface, it means that those objects are related to each other and results into an association
between classes in the class diagram. Initial repetitions for such associations might be detected
by the occurrences of the related objects.

Another recent attempt to create a UI centric development is XUL. XUL is designed specifically
for building portable user interfaces. The supporting software architecture to create a platform
independent information system from the GUI. In addition, a sample commercial application
based on this concept will be introduced.

The Database concept has evolved since the 1960s to ease increasing difficulties
in designing, building, and maintaining complex information systems (typically
with many concurrent end-users, and with a large amount of diverse data).

9.7.1 New System Design Process
In this methodology, we start the design of a new system by first designing the user interfaces
or forms of the desired application. To accomplish this, use cases are going to be determined
first followed by designing the interfaces based on the design of the user interfaces as shown
in Figure 9.8.

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