In Domain Driven Design, domain services should contain operations that do not naturally belong inside an entity.
I've had the habit to create one service per entity and group some methods inside it (Organization entity and OrganizationService service).
But the more I think about it: OrganizationService doesn't mean anything, "Organization" is not a service, it's a thing.
So right now I have to add a Organization deep copy functionality that will duplicate a whole Organization aggregate, so I want to put it in a service.
Should I do: OrganizationService::copyOrganization(o)?
Or should I do: OrganizationCopyService::copyOrganization(o)?
More generally: is a "service" an abstract concept containing several operations, or is a service a concrete operation?
Edit: more examples given the first one wasn't that good:
StrategyService::apply()/cancel() or StrategyApplicationService::apply()/cancel()? ("Application" here is not related to the application layer ;)CarService::wash() or CarWashingService::wash()?In all these examples the most specific service name seems the most appropriate. After all, in real life, "car washing service" is something that makes sense. But I may end up with a lot of services...
*Note: this is not a question about opinions! This is a precise, answerable question about the Domain Driven Design methodology. I'm always weary of close votes when asking "should I", but there is a DDD way of doing things.*
I think it's good if a domain service has only one method. But I don't think it is a rule like you must not have more than one method on a domain service or something. If the interface abstracts only one thing or one behaviour, it's certainly easy to maitain but the granularity of the domain service totally depends on your bounded context. Sometimes we focus on low coupling too much and neglect high cohesive.