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Tiers are defined as any number of levels, arranged one
above another such that each level performs a distinct
task. Each layer can be built and/or maintained without
regard for the implementation of the other layers.
Entire tier implementations can be changed without
affecting the rest of the application.
The Presentation Layer was developed using a
web application framework — providing a configurable
browser-based user interface that ties into the business
layer. Our presentation layer consists of pages, forms,
and information panels that offer an intuitive and easy
to navigate user experience. The data elements and look
and feel of any given page are externally configured
through .xml configuration files. The pages are then
‘painted’ dynamically based on the user role. Our user
interface enables granular configurability with field
level access management. Because the presentation layer
is easily configurable (non-programmatically), clients
have tremendous flexibility to control the look and
feel, flow of windows, and many other attributes of the
system based on the user’s tasks to be performed.
The Business Logic Layer is a configurable
middle tier that provides a robust set of standard
services or business rules that can be configured to
support the business process of a regulatory agency. Our
Business Logic Layer is composed of component services
embedded with decision logic, providing the flexibility
to emulate various rules. We utilize a custom .xml-
based rules engine to allow clients to configure the
business logic non-programmatically. This includes
validation, data translation, and formulas.
The Data Layer implements an Object Relational
Mapping (ORM) framework to allow for Transparent
Persistence. Transparent Persistence is the ability to
directly manipulate data stored in a relational database
in an Object Oriented language (in our case, Java). This
reduces the amount of code as compared to a traditional
JDBC/ ODBC solution, hence reducing time for
development, delivery, implementation, and maintenance.
Our solution also falls in line with the overall
strategy of creating a “platform independent”
application, as the Data Access Layer (DAL) is the point
of access to any backend RDBMS implementation. Changing
the database does not change the DAL; therefore, our
code does not change.
Our DAL uses the Data Access Object (DAO) pattern to
abstract and encapsulate all access to the data source.
DAO hides the details of the persistence solution and
provides a common API to the rest of the application.
This allows us to be very flexible in our transparent
persistence implementation. We can easily convert to EJB,
another ORM vendor, or even JDBC solution with minimal
cost and effort.
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