Nowadays, Enterprise Application Integration (EAI) constitutes a real and growing need for most of enterprises, particularly for large and dynamic ones. Actually, the major problem of EAI is the heterogeneity problem, especially the semantic one. This latter is not correctly addressed by today's integration solutions, which focus mainly on syntactical integration. Dealing with the semantic aspect, which will certainly promote EAI by providing it more consistency and robustness, needs some appropriate principles such as ontology urbanization and mediation. These latter that constitute the main focus of this paper aim to favor the semantic application integration allowing to correctly capture, structure, master and reason upon the semantics, which currently constitutes a big challenge for several enterprises that are in quest of more flexibility and manageability.