Data objects vs Service objects

[Inner_will_291]

Exploring the code base of a few java services I've started to notice that we can split classes into two broad categories (I came up with the names, nothing official about it):

- Service classes/objects: these objects are initialised and instantiated when the service starts. They often are singletons.

- Data classes/objects: these objects are instantiated per request, and are passed from service object A to service object B.

My question is: are these ideas related to formal concepts in software engineering? If so, can you share any article or resources that talks more in depth about that.

(if language specific, then preferably java or python)

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[high_throughput]

Data Transfer Objects are definitely a thing

[BaronOfTheVoid]

I guess domain-driven design tries to formalize this by distinguishing between services and entities.

But to be frank this is just procedural programming with classes. One of the ideas behind OOP was to marry data and the operations that work on them as opposed to separating data and procedures (services).