From jm40@ukc.ac.uk Sun Oct 31 15:49:06 2004 From: jm40@ukc.ac.uk To: "'Campbell, John'" Cc: occam-com@ukc.ac.uk Date: Tue, 5 Dec 2000 21:31:59 -0000 Subject: RE: (now completed) Slides from my talk at CPA2000 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 X-Mailer: Microsoft Outlook CWS, Build 9.0.2416 (9.0.2910.0) Message-ID: <000101c05f02$cd4999e0$661d02d5@JIM1> > -----Original Message----- > From: Campbell, John [mailto:John.Campbell@siinet.trw.com] > Sent: 05 December 2000 17:44 > To: 'Tom Locke'; occam-com@ukc.ac.uk; java-threads@ukc.ac.uk > Subject: RE: (now completed) Slides from my talk at CPA2000 > > > Tom and Others > > > >The problem is that it's not much of an object if you have to sever > > >its existing channel connections before sending it. > > > > Could you elaborate on this? > > What I'm struggling to understand is how you avoid the problems > attendant to aliasing if you transport an object with open > connections. It seems to me that even if you manage to avoid > aliasing of the *object* you're going to get it on the open > *channels*. David May did some work on mobile processes which he presented at WoTUG-21. I asked someone at Bristol for a copy of the relevant papers (an occam-like langage called Icarus), but never heard anything more. It was pretty interesting stuff though, worth looking at for this case. > > I'm supposing that when you move the channel object (as opposed > to a conventional OO object) out of its original context, the > original context cannot communicate with it. That's what I meant > by "sever its connections". Is there a way to limit access to > a sent object such that you don't get aliasing, but it can > still interact with its original environment? If you send a process down a channel, surely it remains attached to the same processes it was before. If you want to communicate with it, you must send the channels themselves to a different process too. I seem to remember all this and more was covered by David May (although he was talking specifically about processes and not full `active objects' (we could debate whether there is any difference for hours I would think...). > > Hope everyone finds this discussion as stimulating as I do. -jc > > Jim Moores