1. A method of updating an implementation object including: creating a first implementation object including a first set of attributes or actions associated with an item of content included in a collection of managed content; creating a first proxy to provide users a first interface for accessing the first implementation object, including accessing the first set of attributes or actions; linking the first proxy to the first implementation object; using a processor to replace the first implementation object with a second implementation object including a second set of attributes or actions associated with the same item of content; creating a second proxy to provide users a second interface for accessing the second implementation object, including accessing the second set of attributes or actions; linking the second proxy to the second implementation object; and using the processor to link the first proxy to the second implementation object so that the first proxy provides a first user, who has possessed the first proxy prior to the replacement, the first interface for accessing a portion of the second set of attributes or actions that are accessible using the same first interface.