## 5 Conclusions and Future Works  
This manuscript contains several contributions that, to the best of the authors' knowledge, have not been matched by the existing literature regarding interoperability for underwater vehicles. A study has been carried out where the software works and tools for interoperability solutions in constrained environments have been assessed, according to their advantages and weaknesses. After the open issues and challenges have been extracted from this study, a solution based on a middleware architecture specifically tailored for autonomous maritime vehicles has been put forward, describing its elements and the reasons to consider that improves the existing state of the art. This solution contains several software components that deal with the most representative functionalities to be expected from middleware (device registration, semantic enhancement of information, requests and responses under a Publish/Subscribe paradigm, etc.). The solution makes use of the capabilities that can be offered from DDS in order to guarantee several features that come in handy for middleware implementation, as well as guaranteeing the interoperability among the different vehicles that have been included in the SWARMs project. Lastly, the implementation works that have been developed have been tested in two different scenarios that prove the feasibility of the proposal described in this manuscript. The testing activities that have been undertaken prove that information can be transferred by means of the middleware solution proposed, which becomes distributed between a partially decentralized element (the Command and Control Station) and the autonomous vehicles that have all the other components of the middleware. When all these aspects are taken into account, it can be said from the middleware solution that has been depicted in this manuscript that it shows promise regarding the integration of the final set of autonomous maritime vehicles that are going to be included in SWARMs. What is more, performance confirms that it will be possible to transfer data through a system of distributed robots in underwater environments with all the features that have been developed for the system. There are several future works that are going to be made during the following stages of development of the middleware architecture. The middleware components expected to be installed in the robots will be done so in the ones provided by other partners. In case there is any challenge for the integration of the components in the architecture, a go-between solution will be developed in order to integrate the autonomous vehicles unable to have the solution installed by means of an interface that will provide connectivity with all the other parts of the system. Furthermore, the extension of the development activities to all the other software components of the middleware guarantees that all the other features will become fully functional by the end of the project without deviations in its schedule. **Acknowledgments:** The research leading to the presented results has been made within the SWARMs European project (Smart and Networking Underwater Robots in Cooperation Meshes), under Grant Agreement No. 662107-SWARMs-ECSEL-2014-1, partially supported by the ECSEL JU, the Spanish Ministry of Economy and Competitiveness (Ref: PCIN-2014-022-C02-02). The Swedish innovation agency (Vinnova) has also provided significant support during the research and implementation works carried out. We would also like to acknowledge the support provided by Twin Oaks Ltd. by offering their software products and technical assistance during the implementation activities done with CoreDX. The authors would also like to acknowledge the help received by other partners from the SWARMs project involved in deploying the network and hardware infrastructure required for the good performance of the presented solution during the Mangalia tests: ECA Robotics, Evologics GmbH, Leonardo Defence Systems and TTI Norte SL.