Created question in FIWARE Q/A platform on 12-12-2018 at 10:12
Please, ANSWER this question AT https://stackoverflow.com/questions/53739662/fiware-entities-and-sth

Question:
Fiware Entities and STH

Description:
I am using the Orion Context Broker, an IoT Agent and Cygnus to handle and persist the data of several devices into a MongoDB. It's working, but I don't know if I'm doing it in the Fiware way, because after reading the documentation I am confused yet about some things:

I don't completely understand the difference between an Entity and an IoT Entity (or device?). My guess is that is a matter of how they provide context data and the nature of the entity modelled, but I would be grateful if someone could clarify it. I am specially confused because the creation of each entity type is different (it seems that I can't initialize an IoT entity at creation time, which I can when dealing with a regular Entity).
I can only persist the data of IoT Entities. It is possible have a Short Term History of a regular Entity?
I don't understand why the STH data is repeating attributes that has not changed. If I have an IoT Entity with two attributes, 'a' and 'b', and I modify both of them, a STH entry is created for each one, which is fine. However, if then I change the value of attribute 'b', two more registers are created: one for 'a' (which hasn't changed and is reflecting the same value that it already had) and one for 'b'. Could someone explain to me this behavior?