## 5 Conclusions and Future Work  
This article describes how semantic technologies can be applied to the application field of production automation. It demonstrates the basic technical feasibility to execute technical processes in the domain of automation using internet technologies which were not initially developed for this domain. Furthermore, it shows that based on the modeling of information and knowledge the adaptability of technical processes can be increased significantly. The presented approach has the potential to offer benefits like seamless information integration, interoperability of factory and business IT systems and highly agile manufacturing equipment. Semantic technologies are very well suited to realize interoperable information exchange. The presented work demonstrates the realization of context-based orchestration of semantic services on a real world example. The knowledge about equipment, functional characteristics, function parameters, plants and devices has been modeled to some extend in several works, but mostly in an informal manner. Besides existing upper ontologies and domain ontologies knowledge about factory concepts is written down in standards and guidelines. In this work those existing knowledge sources are used to create a modular structure of ontologies, which can be extended and combined to a great extent. Following this approach interoperability and reusability are ensured. However, within the domain of industrial control the typical requirements to control systems are availability, reliability, determinism and real time behavior in terms of milliseconds. Amongst others, these are certainly reasons why programmable logic controllers with signal-based point of view and the need for extensive engineering still dominate this domain. Due to limited interoperability of those controllers the domains of automation, business IT and the internet are still strictly divided. On the technical level one promising approach to overcome this barrier is to rethink the system architecture of factory IT. While today this architecture has a strict hierarchical structure with centralized control structures, future architectures based on the paradigm of decentralization and openness can help to fulfill the classic demands to automated control systems while at the same time providing interoperability to open systems like the internet. Future work will have to focus on the reliability and predictability of dynamic context-based orchestration in manufacturing systems. Since in the presented approach open internet technologies are used, IT security and operational safety are further open issues. Realizing context-based orchestration of manufacturing processes the transparency of the equipment's behavior for humans is difficult to keep. Since the decision how to parameterize processes and which service to invoke is taken automatically based on context information, it is very hard to understand a machines behavior for a human. This leads to the question of the human's role in a future smart factory. Here we should look back to the first attempts to use computer technology in factories in the beginnings of the 1980's. Fully automated plants should solve cost and quality problems on the basis of state-of-the-art computer technology. This led to production systems that were extremely complex in planning as well as in construction, operation, and maintenance and in the end did not fulfill the hopes. The solution was to drastically decrease technical complexity and put the humans back into the center of factories [40]. In future factories the humans should be the conductor of dynamically allocated production resources. So in future work the use of information about processes, equipment, functions, _etc._, for assistance systems for human operators will have to be focused. Even work instructions for manual work could be generated dynamically on the basis of context-based dynamic orchestration placing the human worker into the center of the value creation process.