oop - Domain Driven Design question about Services -

I'm reading the domain-driven design quickly and I'm having trouble understanding something.

Authors, entities , value items and services , they talk about the domain model (I mean, concepts), or about implementation already?

What is a service ? A controller ? A stable class?

can be read on a p38:

When a critical process or change in the domain is not the natural responsibility of an entity or value object, a standalone interface declared as a service Operate the model as Define the interface in terms of the model language and make sure that the operation name is part of the omnipresent language. Make the service.

From this lesson, I can conclude:

a) If service is stateless, then this is a controller < / Code> yes. Is this a stable class / singleton ?

b) What does its mean by a interface ? I know what is an interface at the time of coding, but if he is talking about the interface, then he will already be talking about class diagrams and it is not that it is not that Domain model ?

I can clean it as the original of DDD?

Thanks

Focus around understanding and clarity - The implementation details come later.

A Domain Service is basically a class that contains business logic. Must have a static or singleton (here's the opportunity to read dependency injection and service locator ). Stateless is also overloaded: In this context, it means that the service should not act like existence.

Interface describes the methods of domain service, in particular, 'give meaningful names to the methods - names that a business person understands.'

Unfortunately, the term service is also overloaded. See my answer for a description.