The two-tier application programming model was developed to enhance the file server application programming model. As compared with the file server application programming model, the two-tier application programming model provides you with improved usability, scalability, and flexibility of applications.
In Two-Tier model, you will have two seperate layers namely Client & Server.
The applications developed using the two-tier application
programming model have a user-friendly interface.
These applications can support only a few users and
allow data to be shared within a homogeneous environment.
Example of the Model
|The various tiers in a two-tier architecture are separated from each other by physical boundaries.
These physical boundaries can be machine boundaries, process boundaries, or corporate boundaries.
|Two-tier application programming model is a combination of a client application and a server application.
In this application programming model, the client application directly interacts with the server application without the presence of any intermediate application.
Business Logic is coupled either with Client or the Server.
Business Logic In Server
If the Business Logic is coupled with the Client, its called Fat Server with Thin Client.
Business Login In Client
If the Business Logic is coupled with the Server, its called Fat Client with Thin Server.
The Client application communicates with the data layer through a database bridge Application Programming Interface (API).
An Example of a database bridge API is JDBC commonly known as Java Database Connectivity.
The Database driver is installed in each computer that runs the client application.
If the database changes, we need to reinstall Database driver in all the computer.
This increases Deployment cost
Fat Client is bound to a database bridge API, such as relational database API or object database API.
If you change the type of database used by your organization, you need to redeploy and reconfigure each client application
Each client establishes a separate database connection.
Database connections are limited in number and are expensive to establish.
Database Connection is retained even when the client is not accessing the database.
This makes the database connection unavailable to other users.
Therefore Only a limited number of clients can access the database at a time.
High network traffic because of an increase in the number of trips of data transfer across the physical boundaries of the network. Each time a database operation is performed, the data is transmitted across the physical boundary that separates the business logic and data layers
Suitable for environments where business rules do not change frequently and the number of users are limited.
For E.g.: This model can be used to run the localized accounting application of a company.