A Interoperability Approach Based on Asynchronous Replication in Distributed Internet Database Douglas D. J. de Macedo 1 , Hilton W. G. Perantunes 2 , Luiz F. J. Maia 1 , Aldo von Wangenheim 1,2 and M.A.R. Dantas 1,2 Federal University of Santa Catarina (UFSC) Department of Informatics and Statistics (INE) 2 Post-Graduate Program in Knowledge Engineering and Management (PPGEGC) 1 Florianopolis, Brazil 88040-900 {macedo,maia,william,awangenh,mario}@inf.ufsc.br Abstract Nowadays, there is a growing interesting in telemedicine in Brazil, because the country is the fifth largest country in the world and there is a huge gap between the population size and the number of available doctors. Institutions and government are studying solutions for the data integration and availability to be produced by several different systems. In this paper we present a contribution that is characterized by a model oriented to an asynchronous replication strategy between distributed medical databases The contribution, called as PGR, is an enhancement to the Postgres software environment, considering a more lightweight asynchronous operations. In addition, we have implemented a multi-master tool engine with partial replication and hybrid fragmentation targeting to allow interoperability between different telemedicine systems. Our early results indicate that the model and its implementation have reached a successfully level in terms of performance and interoperability. 1. Introduction The eight million, five hundred and eleven thousand, nine hundred and sixty-five square kilometers of Brazil is completed covered by wired and wireless telecommunication facilities. Therefore, an individual in the middle of the Amazon region or in the middle of the Swamp region of the country can get help as a diagnosis assessment from a specialist doctor. This scenario has clearly advantages in terms of territorial cover and usage of hospitals and clinics equipment. This strategy is broadly presented in some researches (e.g. [6]), but different efforts are necessary to attempt local conditions. Because of this, in the south of Brazil, in state of Santa Catarina an effort was established in a project, this was called as Rede Catarinense de Telemedicina (RCTM)[5]. This telemedicine effort, in terms of design and implementation, is executed by the Cyclops Project [16] in the Federal University of Santa Catarina (UFSC). The project offers a telemedicine portal where services such as a second doctor assessment, collaborative diagnosis, hospital available procedures. The RCTM project concept considers a model in which hospitals from all cities of the state realize patient exams, e.g. electrocardiogram, computed tomography, magnetic resonances, X-Ray angiography and nuclear medicine These exams are sent in real time to a centralized database located in the University Hospital. This centralized database is accessed by doctors that execute the necessary diagnosis. This project has proved to be a success and many other states are interesting to implement a similar approach. In addition, as a national plan the idea is to interconnect all databases, avoiding that a patient to have many entrances and similar exams done in different places across the country. Interesting grand challenge problems arise from this national plan, examples that are representative are: scalability issues and telemedicine database replication. This fact leads directly to the motivation of the presented research work, which can be translated as a design and implementation of an asynchronous replication strategy between distributed medical databases. In addition, an important fact is that the final proposal solution would be based upon open source paradigm aiming to provide to all peers of the national project. The paper is organized as follows. Section 2 shows some related work. A brief overview related to theoretical aspects and issues of data replication on distributed systems configurations is shown in section 3. In section 4, it is presented the PGR (Postgres Replication) proposal contribution where there is a widely discussion of the