Supporting hot-swappable components for system software

Summary form only given. A hot-swappable component is one that can be replaced with a new or different implementation while the system is running and actively using the component. For example, a component of a TCP/IP protocol stack, when hot-swappable, can be replaced (perhaps to handle new denial-of-service attacks or improve performance), without disturbing existing network connections. The capability to swap components offers a number of potential advantages such as: online upgrades for high availability systems, improved performance due to dynamic adaptability and simplified software structures by allowing distinct policy and implementation options to be implemented in separate components (rather than as a single monolithic component) and dynamically swapped as needed. In order to hot-swap a component, it is necessary to (i) instantiate a replacement component; (ii) establish a quiescent state in which the component is temporarily idle; (iii) transfer state from the old component to the new component; (iv) swap the new component for the old; and (v) deallocate the old component.