Database Reference
In-Depth Information
All the aforementioned features make possible rapid development of complex, distributed appli-
cations by enabling developers to focus on developing business logic, implementing the system
without being impacted by prior knowledge of the target execution environment(s), and on creat-
ing systems that can be ported more easily between different hardware platforms and operating
systems (OS).
11.2.3.1 Reference Architecture
The objective of the flexibility and reusability can be achieved primarily at two levels: applica-
tion architecture level and the application component design level. The reference architecture
is the vision of the application architecture that integrates the common elements into a compo-
nent structure modeling the current business and also positioning it to meet the challenges of
the future. From a technical point of view, the architecture positions the development organi-
zation to automatically meet the benchmark requirements on time-to-market, flexibility, and
performance.
A set of key elements drive the definition of the reference architecture that comprises of three
layers, namely, business objects, process-oriented or service-based objects, and user interface
layer.
The defining elements of enterprise applications are as follows:
◾
Business Entities
are the foci of the enterprise applications. These range from top-level enti-
ties such as a customer or a supplier down to bottom-level entities such as purchase orders,
sales orders, or even individual level line items of these orders. Entities participate in the
business processes, have attributes or properties, have methods for responding to requests
for information, and have different sets of enforceable policies or rules applicable to them.
The latter include the requirement for persistence of the state of the entities as reflected in
the snapshot of all attributes.
◾
Business Processes
carry out the tasks of the enterprise. They have some kind of specified
workflow and essentially involve one or more business entities. They must be executed in a
secure manner and also be accessible via a host of user interfaces or devices or clients.
◾
User Interactions
carry out the access and display of information related to business entities as
an outcome of some business processes for scrutiny by the users of the enterprise application.
This essentially involves some kind of screen flow or page navigation, attributes for presenta-
tion, user requests, or generated responses, that is, static or dynamic content, form-oriented
processing, and error handling. The user interaction could be via a host of user interfaces or
devices or clients.
Each of these elements gives rise to the three primary architecture layers of the reference architec-
ture. These layers could reside on the same physical layer or be distributed across a network. Figure
11.2 presents the three architecture layers constituting the reference architecture.
11.2.3.1.1 User Interaction Architecture
User interactions are modeled by user interface components that comprise the User Interaction
Architecture. In J2EE platform, this is typically implemented as a combination of servlets and
Java Server Pages (JSP). In a Web-based application, this layer would process HTML form
