Abstract: A client computer, a first server computer, and a second server computer are connected via a network. The client computer executes a transaction process with the first server computer at the normal time. When a fault occurring in the first server computer is detected, first, the client computer requests a connection to the first server computer. When the connection to the first server computer is failed, the client computer requests a connection to the second server computer. When the connection is established, a transaction process is started by the client computer and the second server computer.

Abstract: A crystal substrate, with an adhesive uniformly applied to its entire rear surface, is fixed to the inner wall of an element housing. By adjusting the thickness of a wall of the element housing, forming grooves in the wall, or fixedly attaching a deadweight to the wall, the resonant frequency of the element housing is adjusted so as to restrain the optical waveguide element from resonating. Further, by mounting the optical waveguide device on a printed board via an elastic member or the like, propagation of the vibration to it is suppressed.