An electromagnetic wave generating device is provided which includes an optical waveguide including a plurality of waveguide segments such that the main lobe of a combined electromagnetic wave has a substantially single large directivity. The overfill prevention valve is equipped with first and second floats. The interceptor selects information useful in determining the cause of a failed usage of the service residing in the client server from each intercepted invocation and response messages, writes the selected information to a data store residing in the client server and then re-invokes the intercepted invocation and response messages. 8 with respect to contrast ratio when the voltage applied between the pixel electrode and the common electrode is zero.