A Platform for the Study of Reliable Multicasting Extensions to CORBA Event Service João Orvalho 1 , Luis Figueiredo 2 , Tiago Andrade 2 and Fernando Boavida 2 CISUC – Center for Informatics and Systems of the University of Coimbra Communications and Telematic Services Group - Pólo II, 3030 COIMBRA - PORTUGAL Tel.: +351-39-790000, Fax: +351-39-701266, E-mail: {orvalho, boavida}@dei.uc.pt Abstract. Conference applications play a key role in workgroup tools, and provide an excellent environment for the development and evaluation of proposals concerning multicasting and reliable communications. A nuclear aspect of conference applications is their ability to use multipoint communication in heterogeneous environments. In the scope this work, a platform that uses several extensions to the CORBA Event Service was developed. This platform is based on ITU T.120 recommendations, and supports reliable multicasting communication for both data and control information. The control information is managed by a service implemented in Java TM , according to the CORBA Event Service model. The present paper introduces and discusses the main features of the proposed platform. Also, provides a general description of the conference framework architecture that was built on the platform, with some emphasis on reliable multicasting communication and on system synchronism. In the final part of the paper, the specification and the implementation of the proposed extensions to the CORBA Event Service are presented. 1 Conference Framework Architecture The development of the extensions to the CORBA Event Service [1] and the evaluation of their usefulness were performed using a conference prototype developed for this purpose. This conference framework will be described in this section. 1.1. General Description of the Architecture The conference system is based on the tightly coupled conference paradigm, and has the aim to achieve a high scalability degree. To reach such objectives we have conceived two nuclear services, one for conference control - Conference Controller (CC) - and another one for multipoint communication between collaborative applications (Figure 1). The CC service - as responsible for the administration of the 1 College of Education, Polytechnic Institute of Coimbra 2 Informatics Engineering Department of the University of Coimbra