The development of highly dynamic distributed environments modifies the runtime behavior of applications. Applications tend to use services available everywhere in the environment and would like to, whenever it is possible and/or needed, integrate services offered by the local environment. In particular, if no single service can satisfy the functionality required by the application, combining existing services together should be a possibility in order to fulfill the request. In this article, we propose ANIS: A Negotiated Integration System. Our system provides a framework including a set of integration management interfaces - Integrable, Negotiable, IntegrationLifeCycle - and the tools implementing these interfaces. These tools offer different techniques of integration (local/remote composition, local/remote weaving, deployment by downloading/uploading), negotiation by contracts and the capability to manage the life cycle of the integration. A prototype based on Java platform and OSGi technology is implemented as a proof-of-concept to demonstrate the potential of ANIS