It will work when I'll be done with subtype-based matching. But using marker interface is somehow ugly (even so it is probably the best fit for the Terracotta support).
Somewhat ugly but as we were already using a marker interface (Serializable) it doesn't really change much. Introducing a new interface would only scope implementors to be something Wicket specific, which is what we want here.
Java5 annotations could be a nicer option for such purpose, but then Terracotta don't support matching on annotations yet. Though it would be a good addition too.
You would go from a marker interface to a marker annotation; I don't really see much advantage to that. :) Also, Wicket 1.3 is for JDK 1.4 and up, so we can't use annotations for that (and we don't want to introduce code weaver like constructions either). Eelco
