The Physical View

The CANS network is realized by partitioning the services and data paths onto physical hosts, connected using existing communication mechanisms. The CANS Execution Environment (EE) serves as the basic run-time environment on these hosts and includes the following functional modules (see Figure 1(b)): class manager, plan manager, driver and service manager, event manager, and resource monitor. The class manager handles downloading of component code and instantiation of the components. The plan manager is responsible both for creating the initial plan comprising drivers, services, and data paths in response to a request trapped by the interception layer, as well as replanning in response to system conditions. The driver and service manager maintains information about deployed drivers and manages data path operations, including inserting new drivers, creating new services, and reconfiguring existing paths as required. The event manager is responsible for receiving both system-level and component-level events and propagating these on to interested components. The resource monitor monitors system conditions such as CPU availability or network interface state, informing the event manager when registered trigger conditions fire.