Ian, I have not study the source carefully, but at the first glance, it seemed that two running J processes accessing the same mapped file. Why share_jmf_ was not needed? Please correct me if I missed anything.
Вск, 08 Янв 2012, Ian Clark писал(а): > This is my eventual solution to the "are you alive?" problem: > > http://www.jsoftware.com/jwiki/Scripts/AliveDemo > > It doesn't use sockets, but a couple of mapped files instead. The > (identically coded) processes use them to play pat-a-cake. > > For demo simplicity I've coded a 'hard' duty cycle (a while.-loop.) > rather than one I find much more convenient: a "soft" duty cycle that > posts an event calling itself again after a given interval. > > A "soft" duty cycle has a lot of advantages. You have to play with the > alternatives to appreciate them, but the main ones are that it dies > gracefully if there's a code error, and it doesn't lock the session > window and any UI which the duty cycle happens to be managing. Indeed > the duty cycle runs in the background, keeping all displays up-to-date > and leaving you (almost) full use of J facilities. > > I'll place a "soft" duty cycle code sample on the wiki in a day or two. > > On Mon, Jan 2, 2012 at 6:51 PM, Ian Clark <earthspo...@gmail.com> wrote: > > Please forgive these questions I post to the list to which I know the > > answer. Or rather: *an* answer. I learn a lot from others' responses. > > Even if it's "my way is best after all" -- that's a valuable thing to > > know. > > > > I have two separate J processes running (assume Linux / Darwin, though > > I'm keen on cross-platform solutions). They communicate by each > > writing a text file which is read by the other > > (keep-it-simple-stupid). Is there a neat, robust way of one process > > asking the other: "are you there?" or "are you still alive?" > > > > I'm au-fait with how the yellow-J works, all the solutions involving > > timer-driven duty-cycles, timeouts, and reading files written by the > > sister process, Or the files' timestamps, or permissions. But these > > all seem so clunky. I guess what I want is something that was so easy > > in the 1970s but is so awkward on today's machines: just reserve a > > pair of bits in absolute memory -- or a pair of pixels on the screen > > -- or some inessential system flags -- and play pat-a-cake with them. > > > > Once upon a time there was such a thing as "common memory". > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm -- regards, ==================================================== GPG key 1024D/4434BAB3 2008-08-24 gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
