Context Sensitive History Part 1 Of 2

24 Feb 2010

A Desktop and Silverlight user action management system, with undo, redo, and repeat. Allowing actions to be monitored, and grouped according to a context (such as a UI control), executed sequentially or in parallel, and even to be rolled back on failure.

A ‘task’ is the term I use to describe application work units, instigated by the user or the system.

The main features of the task management system provided in this article are:

  • Tasks can be undone, redone, and repeated.
  • Task execution may be cancelled.
  • Composite tasks allow sequential and parallel execution of tasks with automatic rollback on failure of an individual task.
  • Tasks can be associated with a context, such as a UserControl, so that the undo, redo, and repeat actions can be, for example, enabled according to UI focus.
  • Tasks can be global, having no context association.
  • The task system can be wired to ICommands.
  • Tasks can be chained, in that one task can use the Task Service to perform another.
  • Return to a point in history by specifying an undo point.
  • Coherency in the system is preserved by disallowing the execution of tasks outside of the Task Service.
  • Task Model compatible with both the Silverlight and Desktop CLRs

Read on…