1. A computer-implemented method performed on a server in a network, comprising: storing in the server a structured document associated with an application that is executable on the server, the structured document defining a request URL mapping to the application and at least one rule for composing an instance of the application on the server using a set of one or more components, each of the components being defined in the structured document by a URI-addressable path and being one of: a presentation component, a code component and a data component; responsive to receipt at the server of a client request from a client, evaluating the client request; if the client request includes the request URL mapping to the application, retrieving the structured document associated with the application; using the structured document to compose an instance of the application on the server that includes the one or more components as defined in the structured document; generating a response to the client request using the instance of the application that has been composed on the server upon receipt of the client request; delivering the response to the client; after a given time period following delivery of the response, invalidating at least one component in the instance of the application so that the instance of the application is no longer available to respond to new client requests received at the server; and automatically invalidating any other component that was derived from the at least one component when the instance of the application was composed.
1. A computer-implemented method performed on a server in a network, comprising: storing in the server a structured document associated with an application that is executable on the server, the structured document defining a request URL mapping to the application and at least one rule for composing an instance of the application on the server using a set of one or more components, each of the components being defined in the structured document by a URI-addressable path and being one of: a presentation component, a code component and a data component; responsive to receipt at the server of a client request from a client, evaluating the client request; if the client request includes the request URL mapping to the application, retrieving the structured document associated with the application; using the structured document to compose an instance of the application on the server that includes the one or more components as defined in the structured document; generating a response to the client request using the instance of the application that has been composed on the server upon receipt of the client request; delivering the response to the client; after a given time period following delivery of the response, invalidating at least one component in the instance of the application so that the instance of the application is no longer available to respond to new client requests received at the server; and automatically invalidating any other component that was derived from the at least one component when the instance of the application was composed. 6. The method as described in claim 1 wherein the instance of the application is composed by combining first and second presentation components and generating a third, derived presentation component.