Major Components
The functionality of the active network node is divided among the Node Operating System (NodeOS), the Execution Environments (EEs), and the Active Applications (AAs). Each EE exports a programming interface or virtual machine that can be programmed or controlled by directing packets to it. Thus, an EE acts like the ``shell'' program in a generalpurpose computing system, providing an interface through which endtoend network services can be accessed. The architecture allows for multiple EEs to be present on a single active node. However, development and deployment of an EE is considered a nontrivial exercise, and it is expected that the number of different EEs supported at any one time will be small.[4]
The general organization of these components is shown in Figure 1.
figure 1. Components of Active Networks.