What's the difference between @Component, @Repository & @Service annotations in Spring?

Question

Can @Component, @Repository and @Service annotations be used interchangeably in Spring or do they provide any particular functionality besides acting as a notation device?

Answer 1

A @Service to quote spring documentation,

Indicates that an annotated class is a "Service", originally defined by Domain-Driven Design (Evans, 2003) as "an operation offered as an interface that stands alone in the model, with no encapsulated state." May also indicate that a class is a "Business Service Facade" (in the Core J2EE patterns sense), or something similar. This annotation is a general-purpose stereotype and individual teams may narrow their semantics and use as appropriate.

If you look at domain driven design by eric evans,

A SERVICE is an operation offered as an interface that stands alone in the model, without encapsulating state, as ENTITIES and VALUE OBJECTS do. SERVICES are a common pattern in technical frameworks, but they can also apply in the domain layer. The name service emphasizes the relationship with other objects. Unlike ENTITIES and VALUE OBJECTS, it is defined purely in terms of what it can do for a client. A SERVICE tends to be named for an activity, rather than an entity—a verb rather than a noun. A SERVICE can still have an abstract, intentional definition; it just has a different flavor than the definition of an object. A SERVICE should still have a defined responsibility, and that responsibility and the interface fulfilling it should be defined as part of the domain model. Operation names should come from the UBIQUITOUS LANGUAGE or be introduced into it. Parameters and results should be domain objects. SERVICES should be used judiciously and not allowed to strip the ENTITIES and VALUE OBJECTS of all their behavior. But when an operation is actually an important domain concept, a SERVICE forms a natural part of a MODEL-DRIVEN DESIGN. Declared in the model as a SERVICE, rather than as a phony object that doesn't actually represent anything, the standalone operation will not mislead anyone.

and a Repository as per Eric Evans,

A REPOSITORY represents all objects of a certain type as a conceptual set (usually emulated). It acts like a collection, except with more elaborate querying capability. Objects of the appropriate type are added and removed, and the machinery behind the REPOSITORY inserts them or deletes them from the database. This definition gathers a cohesive set of responsibilities for providing access to the roots of AGGREGATES from early life cycle through the end.