中文说明：Bubble-cast 是bubblestorm的P2P系统的主要搜索函数，bubble-cast采用了带有控制的分支搜索算法，本身保证一定的搜索量。与传统的flooding相比，bubble-cast的granularity更加优良
English Description：
Bubble cast is the main search function of the P2P system of bubblestorm. Bubble cast adopts a branch search algorithm with control, which can guarantee a certain amount of search. Compared with the traditional flooding, bubble cast has better granularity