The industrial systems found in factories often have nothing to do with the systems that are known in IT. No REST API, no database (or few), and obviously no default message bus. However, it is necessary to be able to connect this small world together in order to collect data that will be used for analysis on Big Data or to do machine learning. However, this dream of solutions such as Microsoft Azure's IoT suites and AWS GreenGrass to connect your plant is totally unrealistic if you don't simply connect to industrial systems to recover data.
What are these industrial systems?
Forget about REST API, JDBC, BAPI, File, and all the other known means of exchange in a classic IT. Our new friends are called: