Fig16. Layers of
three-tier logic architecture
3.2.2.1 Presentation
layer
The presentation is the most immediately visible
to the user; it provides interactive access to the application. (You
could argue that user interaction layer might be more appropriate.)
3.2.2.2 Business logic
layer
§ Services
Layer
This layer combines the technical
treatments; non-functional requirements are
supported by the Framework Development.
§ Business
objects
these objects are the essential
work related to the
field of application. They require
treatment techniques, non-functional service
layer to manage security, transaction, competition.
3.2.2.3. Persistence layer
It consists of the database. Most often we add a layer that
makes the correspondence between objects and the database (DAO). This
layer is often used to cache objects retrieved from the database and thus
improves performance and security.
3.2.2.4 Advantages of three tier
architecture
Three-tier implementation have several advantages
including:
§ The logic is moved at the application server but is
programmed using the same technologies related to relational databases.
§ The ease of deployment; the application itself is
deployed on the server side (application server and database server). The
client requires only a minimal installation and configuration. Indeed, client
must only install a web browser to access application. This ease of deployment
will not only reduce the cost of deployment but also enable a steady evolution
of the system.
§ This development will facilitate the updating of the
application on the application server.
§ Improved security; using three-tier architecture of
database access is made only by the application server. This server is the
only one to know how to connect to the database. He does not share any
information that allows access to data, particularly the login and password of
the database. It is then possible to manage security at the application
server, for example by maintaining the list of users with their passwords and
their access rights to system functions.
§ We can even further improve security by establishing a
network architecture completely prohibiting access to the server database for
end users.
| 
