A back sheet for a solar battery module that is less likely to cause a rise in temperature by irradiation with rays of the sun even though displaying a black color in appearance, and is less likely to discolor even after a long-term use thereof while suppressing a rise in cost. The method includes ascertaining at the sending node if the media to be transmitted is either time-sensitive or not time-sensitive. Prior to downloading an application, the communication terminal determines an amount of memory capacity required by an application client to be downloaded from the server device.