A spark plug includes: a rod-shaped center electrode extending in an axial direction; an insulator including a shaft hole that holds the center electrode inside of the shaft hole; a metal shell surrounding and holding a part of the insulator; and a ground electrode including a base end welded to the metal shell. The ratchet shaft includes, at its base end with a flange collar, a first stepped portion that supports a ratchet lever to be rotatable, and a second stepped portion that receives the thickness of a base plate at the front end of the first stepped portion. The first Java module includes a first entity bean and a first state object in communication with the first entity bean.