5. The XML virtual machine as recited in claim 1 , wherein defining a set of runtime objects for executing an application includes registering a notifier object that represents a trigger encountered in application code with a trigger event bus, the registered notifier object identifying at least a user interface component and an event type that will activate the corresponding trigger.
5. The XML virtual machine as recited in claim 1 , wherein defining a set of runtime objects for executing an application includes registering a notifier object that represents a trigger encountered in application code with a trigger event bus, the registered notifier object identifying at least a user interface component and an event type that will activate the corresponding trigger. 6. The XML virtual machine as recited in claim 5 , wherein the method further comprises: receiving notice at the trigger event bus that the user interface component experienced the event type as specified by the registered notifier object; and activating the notifier object and causing an application process step to be executed.