A great deal of it should be, yes, and also a lot of it shouldn't be or can't be. So what we're talking about with service-oriented RIA is not really replacing the business tier of any enterprise application. More of what we're talking about is aggregating the business tier and multiple enterprise applications (using the client). In some cases, they're so loosely coupled, these services, that the enterprise developers have done their work, encapsulated the logic behind service endpoints. They're so loosely coupled that they can't very easily be aggregated on the server in a way that takes advantage of user behaviours, and understands the way users want to interact with a given piece of data at any given moment, regardless of the state of the network. So some of the aggregation has to take place on the client. In particular, one of the obvious cases where users or developers would want to consider taking care of this aggregation on the client is when a lot of work is spent on the server, usually on the presentation tier, reconstructing state on behalf of the client. Often what happens in today's multi-tiered J2EE applications is that the presentation tier spends a lot of time reconstructing the state of the client and piecing back together knowledge of the client. And in the end it usually still knows very little about the client. It knows some environmental variables and some recent data that's been stashed in the session. But it doesn't have very fine-grained knowledge of everything that the end user happens to be doing on the device that he's currently using. So in those cases, rather than spend a lot of extraneous network round trips piecing back together state, it does make sense to take care of a lot of that on the client and keep the serverside services fairly stateless and aggregate them on the client where possible. So I guess the idea is that services are still composed on the server, but they're handled in that way according to best practices and appropriate patterns depending on the use case at hand and not because that's the only mechanism that's available because now there's a choice. And the applications that I want to use and the applications that I want to develop really involve the collaboration of some client side aggregation along with some server side aggregation.