In recent years, the rapid growth of distributed embedded systems have been vigorously pushing middleware systems and technologies in different areas like: telecommunications, health care, automotive, defense, avionics, etc. The aim of this master thesis is to develop a new optimized version of the middleware MAREA 1, a software specifically designed to fulfill Unmanned Aircraft Systems (UAS) communications and their application to the design of complex distributed UAS avionics. This document presents the software architecture of MAREA 2 and discusses design decisions, as well as some of the techniques employed to develop the middleware. MAREA 2 provides a more modular, flexible and reusable architecture and implements some new functionalities and features proposed in Service Oriented Architecture for Embedded (Avionics) Applications (López J., 2009). Another of the main contributions of this master thesis is the performance evaluation and opti mization of the middleware through the analysis of some key performance parameters. The present document provides a comparison between the new and previous version of the middleware both in terms of design and performance