Within the past years the web service technology emerged into more and more fields of application. In some cases the classical approach of using HTTP as a transport binding for SOAP seems no longer adequate. As a full scale application protocol HTTP causes a high amount of protocol overhead and is too inflexible for many web service scenarios. In this paper we will initially give an in-depth review of existing transport bindings with a strong focus on data rate efficiency. Then we will introduce an advanced UDP binding called PURE that significantly reduces the protocol overhead and enables interesting additional features such as point-to-multipoint communication via IP multicast and broadcast.