createDependency Step Reinstall Implications

A component install is considered a reinstall if there is a pre-existing component in the same version tree that is installed on the same host and install path. A component may be reinstalled if and only if the new component also satisfies all the dependants of the original component. A component can always be reinstalled with the same version component, but can only be reinstalled with a different version if the new version also matches the constraints specified in the <createDependency> step that created the persistent component.

When a simple install block of a component is encountered, we determine if the install will overwrite an existing install. If so, then we find all persistent dependencies for which the existing component is the dependee, and re-verify that the constraints of the dependency are still satisfied with the new component being installed. If any are not satisfied, the install of the new component fails, and the original component remains installed. Otherwise, if and when the new component has successfully completed its install, it becomes the new dependee on all persistent dependencies. Also note that when the install of the new component successfully completes, then the original component is considered uninstalled, and all the persistent dependencies for which it was the dependant are removed. This implies that the new component is responsible for recreating dependencies as needed.