How automatically DAO methods get called upon

[PavanPL KalyanK]

I am new to Java J2EE development , so please help me even my doubt is a prank

Here is my query :

I have a DAO to perform operations on database :

public interface MyDAO
{
public void insert(Employee employee );
public List getData(Employee employee);
}

and i have a sessionbean that implements this MyDAO

public class MyClass implements MyDAO
{
public void insert(Employee employee )
{
//some coding here
}
public List getData(Employee employee)
{
//some coding here
}

}

I want to know upon calling a DAO interface from the servlets (Correct me if i am wrong) how the DAO implementation class would be get called upon ?