VO Paris Data Centre is a collaboration between Observatoire de Paris, IAP, and IPSL to promote the Virtual Observatory and develop data centre activities. Our mission is to share the data centre infrastructure as well as the knowledge in standards and software, and competence in technologies. Our implication in development of standards and participation to the IVOA (International Virtual Observatory Alliance) led us to develop a service validator. After this first step we decided to gather statistics on service compliance in the IVOA. We also tried to define metrics to characterize their evolution. Finally, we plan to contact providers to encourage them to modify their services so that they become VO compliant.