Context information is one of the most important data coming from mobile devices to add a value for the application execution. This paper introduces a context dissemination middleware based on a mobile Web Services framework. In a P2P environment, each context source/provider offers services to other devices. A monitor service is proposed which reduces the communication amount between devices and decreases the reaction time according to context changes. Moreover, to provide monitoring service of arbitrary context information, a rule description (policy) language has been designed. The paper presents an exemplary application in the health care domain to demonstrate the use of the middleware. Additionally, the application development process is described to point out the strength of the middleware for application developers.