Current CSCW models give no preferential treatment to the processing of collaborative applications. However, to ensure effective collaboration among large number of diverse and distributed applications, it becomes imperative that some applications should be treated differently than others. This paper proposes a new Web services-based model that enables differentiated treatment of collaborative applications. The proposed model is based on three-layered architecture such that it processes various and diverse in nature collaborative applications. It assigns different grades of services to different collaborative applications. This model provides collaborative applications with better quality of service such as improved performance and prioritised service.