The linked Tutorial gives a brief overview of all the steps that are necessary to integrate a RC522 RFID Reader via Raspberry PI into NodeRED environment using IBM Bluemix services, watson IOT and nodes.

Very interesting and quite easy to do:

https://developer.ibm.com/recipes/tutorials/reading-rfid-mifare-cards-into-watson-iot-platform-using-your-raspberry-pi-3/