ofbiz entity engine vs. PropertySet

[sangmoonpark]

I am a developer using Jira. During research into the technology stack, we also found that we had direct access to the engine at Jira core and access it via PropertySet. Can you tell me under what circumstances you are using these two approaches?
And I would also like to know about the specific features of entity engine and PropertySet.

[Aron Gombas _Midori_]

If you are looking for the persistence technology in general, them ActiveObjects is the modern standard way of storing data in Atlassian apps.

[sangmoonpark]

So is propertyset or ofbiz entity engine not in use today?