<blockquote><i> there is, however, a use for service contracts in these core packages. Think of 5 packages that depend on user-preferences. The user-preferences UI needs to link back out to those 5 packages, to provide relevant information in a summary screen. Thus, a reverse-dependency contract, called user-preferences-extension, is very useful to implement callbacks into these extensions.
</i></blockquote>
Yes, this is exactly what I was thinking about. A service contract exposes the API to the package developer and also checks to make sure that they're at least claiming to return the right stuff.
<p>I don't mind if there's a predefined and well-documented PL/SQL and Tcl API in the other direction.
