How does the architecture for such a platform should like? As we are facing it from the business side, let's stay with model driven architecture (people opting for another architecture please leave their comments below). We have the entity, as heart of our abstraction. The entities compose via compositions and associations, forming complex graphs. Entities do have identity (key), their factories, the set of properties, and a set of services (to allow validation of incoming data modification messages). This is where our persistent data abstraction finishes, and our business logic abstraction starts. Former is to handle defaulting, validation and calculated values; latter for handling complex transaction and customization scenarios. What does the latter contain? Cancellable and reversible operations (with possibility for operations to compose other operations for complex business logic chains), that operate on entities. These too have services, that support long running transactions, has parameters, factory, and selectors that for operations capable of supporting multiple services select the relevant at runtime.
These are the first level concepts of a model in my ideal model driven architecture. Moreover, we can define concepts like a change set – set of entities and operations that are running on top of them that can be committed and aborted together; so we are forming transaction abstraction as well. For the entity we can drop in some cubism as well – have measures and dimensions.