Much research has been performed to represent music information on computers. However, one problem of the previous approaches is that music information cannot be hared with other music systems since they have used their own representation schemes. In order to resolve this problem, we have developed a new scheme for representing, editing, and playing rhythms among music information based on XML which is a web standard language. We present a RDML (Rhythm Description Markup Language) to exactly describe rhythm information such as beats, musical instruments, and performance information, which is much simpler thant previous representation schemes. Moreover, the RDML representation can be played by converting it into SMIL representation. Because our approach is based on the web standard, the music information can be shared on the web.