The JDBC API supports both two-tier and three-tier processing models for database access but in general JDBC Architecture consists of two layers:
This provides the application-to-JDBC Manager connection.
This supports the JDBC Manager-to-Driver Connection.
The JDBC API uses a driver manager and database-specific drivers to provide transparent connectivity to heterogeneous databases.
The JDBC driver manager ensures that the correct driver is used to access each data source. The driver manager is capable of supporting multiple concurrent drivers connected to multiple heterogeneous databases.
Following is the architectural diagram, which shows the location of the driver manager with respect to the JDBC drivers and the Java application: