Project Service Extension - how works?

Project Service Extension - how works?

Hi All!

I created my first Project service and i do not understand how it works because code which i added execute only one time. I added it here:

public class ProjectServiceExtension : IProjectServiceExtension
    {
        #region IProjectServiceExtension implementation

        public void Start(IProject context, IBehavior behavior)).
{
             here is my code
}

i thought that service is working over and over with some period time.

Maybe i can add something code which cause that code starts executed over and over not only one time after start service?

Thanks
Patryk