High-level Analysis of the
Architecture
1.1
Basic Three-Tier Architecture
Three-Tier Architecture has three layers User
Interface layer, business logic layer and the persistence layer.
The three-tier software architecture emerged in the 1990s to
overcome the limitations of the two-tier architecture the third tier (middle
tier server) is between the user interface (client) and the data management
(server) components. This middle tier provides process management where business
logic and rules are executed and can accommodate hundreds of users (as compared
to only 100 users with the two tier architecture) by providing functions
such as queuing, application execution, and database staging. The three tier
architecture is used
when an effective distributed client/server design is needed that provides (when
compared to the two tier) increased performance, flexibility, maintainability,
reusability, and scalability, while hiding the complexity of distributed
processing from the user.
1.1.1
3-Tier
Architecture
The 3-tier architecture overcomes the weaknesses
of the 2-tier and
client/server architectures. It contains a client workstation, a component
server, and a database server. The user interface is on the client side while
business logic and data management are in dedicated tiers. Business logic resides
on one machine where it can be easily managed. Successful implementation of a
3-tier architecture requires considerable
applied experience.
n-Tier
Architecture
The n-tier architecture is the same as the
3-tier architecture, but it has multiple (n)
component and data management servers. It can distribute components across
multiple servers and can access data in multiple databases. However, it requires
careful planning of component interfaces to enable re-use and sharing.
1.1.2
Tier-to-Tier Communication
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Communication between the
user interface and business tiers can be achieved by
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Communication between the business and
persistence tier can be achieved by
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JDBC
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