Mastering Microservices with Java - Third Edition

Value objects

Value objects (VOs) simplify a design. Entities have traits such as an identity, a thread of continuity, and attributes that do not define their identity. In contrast to entities, value objects have only attributes and no conceptual identity. Best practice is to keep value objects as immutable objects. If possible, you should even keep entity objects immutable too.

Entity concepts may bias you toward keeping all objects as entities, as a uniquely identifiable object in the memory or database with life cycle continuity, but there has to be one instance for each object. Now, let's say you are creating customers as entity objects. Each customer object would represent the restaurant guest, and this cannot be used for booking orders ...