Gilgul is an extension of the Java programming language that allows for dynamic object replacement without consistency problems. This is possible in a semantically clean way because its model strictly separates the notions of reference and comparison that are usually subsumed in the concept of object identity. This paper sketches problems that occur in attempts at replacements of active objects and presents some solutions, including both variants that preserve consistency and those that trade

more »

... nsistency for timeliness. The latter are enabled by means of the new recall construct that even allows for the replacement of objects with non-terminating loops.