[e-lang] Events as Bad Ideas

Jonathan S. Shapiro shap at eros-os.org
Thu Dec 2 22:12:59 EST 2004


On Wed, 2004-12-01 at 08:51 -0800, Karp, Alan H wrote:
> Shap wrote:
> > 
> > Oddly enough, it looks like Coyotos is going to abandon this. It turns
> > out that you *don't* need a return. What you need is the ability to
> > transmit a capability on which the returned message should be 
> > sent. You
> > also need a way to invalidate this efficiently.
> > 
> This is exactly what e-speak did, so we know it works.  In fact, there's
> a nice feature you can use.  The capability for the return message can
> point to someone else.  We made good use of that ability for error
> returns (stderr).  We could have an error handler that did some fix-up
> of an error and then forward the result to the original requester.
>  
> What do you mean "invalidate this"?

I cannot remember if I replied to this already.

I meant simply that there is a need to revoke the reply capability,
possibly with high frequency. This is necessary in order to have at most
one reply to a procedure call. Most language runtimes don't cope well if
they issue an RPC that gets more than one reply.

The problem is that the reply capability needs to be revoked without
revoking the process that it names....


shap
-- 
Jonathan S. Shapiro <shap at eros-os.org>



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