Re: Cancellation forwarding protocol (was Re: Reliability of RPC services)

[Jonathan S. Shapiro]

On Fri, 2006-04-28 at 14:06 +0200, Bas Wijnen wrote:
> On Thu, Apr 27, 2006 at 04:06:35PM -0400, Jonathan S. Shapiro wrote:
> > Because of this, the operation that you want here is Discrim.
> > 
> > HOWEVER!!!
> > 
> > This case is so universal that there will be a safeGetType() method on
> > the discrim interface. Discrim.safeGetType() will perform:
> > 
> >    {
> >     if (discrim.classify(theCap) == ctInvalid
> >            return ctInvalid;
> >         else
> >            return theCap.getType();
> >    }
> > 
> > This is actually implemented at the library level, and I had forgotten
> > about it.
> 
> So if the capability is invalid, it isn't invoked, but ctInvalid is returned
> instead.  However, if it is valid, the capability is invoked in order to get
> the type, and a reply capability is thereby invalidated.

Yes, I see that the pseudo-code I gave above is incorrect. One only
wants to do the classify part for the cancellation protocol.

Also, one *never* wants to do gettype on a reply capability.


shap