Saturday, 9 May 2009

EXPRESS the Dilemma

As I started implementation, some ideas are popping into my head, I know this should happen more often :) but anyhow...

We can view the Semantic Data in an EXPRESSive system as an interface to the client, which tells it how to interact with the system. The simple CRUD operations affect the Semantic interface in the same way no matter what the system is. What differs however is the business logic which is triggered or reflected by the CRUD operations on the Semantic interface.

There are two levels of actions associated with EXPRESSive systems: actions on the Semantic interface, and actions by the business logic. In fact there are three types if we count actions in the real world. I will illustrate that with an example, when a customer orders a pizza:

-on the Semantic interface level, an order instance containing the details of the order is created, with connections to related instances such as customer and pizzas.
-on the business logic level, the database is updated and notifications are issued.
-the real world level, pizzas are baked then delivered.

  • What is this interface? Is it an OWL or RDF file, a triple store, or a triple space.
  • Does the client query the interface structures to infer what happened and what should happen?
  • Isn’t this the application state? Shouldn’t the client keep track of that?
  • Maybe it isn’t the application state, maybe the server state was altered –by the server or by the client- and the server has to show it?
  • Why is this interface important? It shows the consequences of the action.
So What does all that imply?
  • There will be messages exchanged between the Semantic Interface level and the business logic level.
  • In the case of simple data management there is no business logic level.
  • The generation of the Semantic interface can be automated.
In the next post I'll either clarify or complicate things further

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