Many studies have been carried out to add more value to the available information in the Web with a view to improving the results of the users' interaction with the Web.Semantic Web is one line of research with focus on this issue and proposes the insertion of semantic information to the current Web through ontologies. Several patterns have been proposed by W3C, the international organization that defines patterns to the Web as an attempt to make the Semantic Web viable. However, besides patterns, it is also necessary to create or adapt tools to explore their potentialities. Application Server is a tool which gives significant support to the current Web and could be adapted to work with the Semantic Web. By adding semantic information, in the ontology form, we have an Ontology-Based Application Server (OBAS). This study develops a protoptype system which aims to offer the minimum characteristics of an OBAS. We have therefore investigated the semantic web which could provide a solution according to the patterns recommended by W3C. Properties and behaviors of software components of OBAS are semantically related by means of ontologies. Given that ontology is an explicit conceptual model, its component descriptions can be consulted and inferred, and hence improve the performance of the server. This is done by applying the most appropriate components to a given task and simplifying programming since components can be activated with no need to know all their details. vi vii Sumário 1 Introdução .