The first stage on your way to the Smart Factory is the "transparent factory". That means, that the responsible production employees know at all times what is happening in the shop floor. That is where the "reactive factory" (stage 2) sets in: collected data is compressed and properly visualized in order to quickly recognize the impact if changes are introduced to the shop floor. This is essential in order to react quickly with targeted measures to interruptions in the shop floor. Then, we arrive at the third stage, the "self-regulating factory", where you can develop local standards for production processes based on achieved reactivity. And finally, you arrive at the fourth stage the “functionally linked factory". This final step considers associated processes and systems like PLM, energy and site management. 

The third and fourth stage partly exceed the performance scope of today's MES systems.  State-of-the-art Manufacturing Execution Systems such as HYDRA already offer valuable support though, e. g. to design decentralized loops like eKanban or connecting PLM systems to production.