Plug-and-Produce technologies real-time aspects

Plug-and-Produce (with the meaning that devices can be plugged in without any manual configurations needed) is an attractive paradigm for manufacturing systems, and in particular for Small and Medium Enterprises (SMEs) that do not have the expertise of system integrators but do need to be able to reconfigure their systems by themselves. One approach for loosely (in terms of timing) coupled devices is that of Service-Oriented Architectures (SOA). As can be understood from developments with multiple robot arm and online operator interactions, future applications will in some cases need real-time guarantees for performing services. That includes both real-time communication and the need to perform services with a predictable timing. A review of available technologies and inherent limitations of distributed computing leads to the conclusion that the standard SOA approach based on process oriented (like for RPCs and web services) calls similar to distributed object will not be practically usefu. Instead, a data or state centric approach should be adapted together with one-way message-based communication.