Paralleling with the expansion of robot technology to social activities such as home use, community work, and entertainment, robot communication technology must expand from closed networks to the Internet. Unlike closed networks, robot communication over the Internet must be based on loose process coupling between robots. Web Services technology fits this requirement, but requires middleware supporting Web Services for robot communication to implement robot application software in this environment. Most existing middleware does not fully conform to this requirement because it mainly targets enterprise systems rather than robot applications. We propose a middleware framework for loose robot communication over Web Services based on OpenSOAP, an open-source middleware for Web Services. The framework realizes several essential features for loose robot communication, including bidirectional communication, a new concept called task service, asynchronous messaging, and task forwarding. The results of this study, while based on OpenSOAP, are applicable to other middleware technologies.