Rural Federal University of Semi - Arid , Brazil

We would like to thank our family for the support they provided us and, in particular, we must acknowledge Luana (Milton’s wife) and Yaskara (Pedro’s wife) and our children João Pedro, Maria Eduarda and João Guilherme (Milton’s children) and Yasmin, Yngrid and Pedro Filho (Pedro’s children). We would like to thank too our parents Benedito and Maria José (Milton’s parents) and Paulo and Meyre Ester (Pedro’s parents) by their love and dedication. We would also like to thank our colaborators of the Technological Nucleus in Software Engineering, who have supported us with their comments for this book.