Department of Computer Systems;
Federal University of Paraba;
Jodo Pessoa 58051-900;
Brazil;
Department of Information Systems;
State University of Santa Catarina;
Sao Bento do Sul 89283-081;
Brazil;
Department of Informatics Engineering;
University of Coimbra;
Coimbra 3030-290;
Portugal;
Centre for Informatics and Systems;
University of Coimbra;
Coimbra 3030-290;
Portugal;