UML22 — InstanceSpecifications

To better express links with InstanceSpecifications, InstanceSpecification should be able to reference Slots owned by other InstanceSpecifications similar to an Association's memberEnd. Currently, when modelling an object diagram with a link like the one in fig. 7.54 on p.85, the specification is unclear on which of the involved InstanceSpecifications (Don, Josh, assoc) should own which Slots (father, son). Assuming that the involved association ends are ownedAttributes of the respective classes (Person), one would expect the object specifications (Don, Josh) to have Slots for these ends. Similarly one would expect the link InstanceSpecification to somehow reference its ends. Since a Slot can only belong to one InstanceSpecification, this is currently only possible by duplicating Slots and InstanceValues between object and link InstanceSpecifications (at least that is how e.g. Rational does it). This leads to two problems. First there is of course a lot of redundancy and chances for inconsistency. Second, and more importantly, there is no easy way to navigate from an object InstanceSpecification to the "connected" link InstanceSpecifications. On type level, an association can reference member ends that are owned by other classifiers. For the sake of consistency and simplicity, we would suggest something similar on the instance level for the InstanceSpecification-Slot relationship, i.e. a memberSlot referencing Slots owned by other InstanceSpecifications (maybe in a specialized LinkSpecification). I have created some diagrams to better illustrate the problem, albeit for a different example: - The example: http://www.reckord.de/uml/example.png - What it currently looks like on the meta level: http://www.reckord.de/uml/example-metaobjects.png - What it could look like: http://www.reckord.de/uml/example-meta-fixed.png

Merged with 9961