The invention relates to a wave power device 1 for the extraction of energy from waves in a liquid 3. A platform-independent application programming interface is disclosed, as well as an abstract database layer. The incidental content data is not the one that is produced by arranging directly the primary content data as an editing material but play control information for giving an instruction defining a play mode. The system administrator initiates the actions by manipulating the action icon such that it overlaps a computer icon, which embodies one or more computing devices within the network that will execute the selected actions. Secret information required to generate the authentication information for user authentication is held securely at low cost. The distal end guiding element is made of a thin-film resin member and expandable by fluid.