I have a domain-specific application that is used by a few customers. The customers each have their own specific requirements. Sometimes extra fields, sometimes different rules and funcitonality.
The domain objects change very little but the customer. Because the domain objects are fairly static I opted for anemic domain model with fine-grained services layer. The services layers implement customer-specific functionality (use cases) and are individually deployed. My 'problem' with the rich domain model (data + behaviour) is that the behaviour becomes messy. I dont think new domain models per customer is a great idea.
My question is what is the best architecture and deployment model for this.