Systems and methods for implementing a bidirectional multicast protocol with two types of join messages are disclosed. If the item has not been previously requested, it may not be stored in the cache. The high frequency magnetic thin film of the present invention exhibits the properties such that the real part of the complex permeability is 400 or more at 1 GHz, a quality factor Q is 4 or more, and a saturation magnetization is 14 kG or more.