Re: [LAU] [Jack-Devel] session management API proposal, take 3 (fwd)

All: Based on some of the recent discussions on LAD and LAU, I thought it prudent to forward this message from the Jack-Devel list. If you wish to continue the discussion on the the Jack session management API, please do it on the Jack-Devel list. Scroll down to the very bottom for a URL to the list. -gabriel ---------- Forwarded message ---------- Date: Thu, 4 Mar 2010 18:16:39 -0500 From: Paul Davis <paul(a)linuxaudiosystems.com> To: jack-devel(a)lists.jackaudio.org Subject: Re: [Jack-Devel] session management API proposal, take 3 [ ... chatter chatter chatter ... ] i'm on the verge of approving the API proposed by Torben for inclusion as part of the JACK API. I believe that it accomplishes the goal of leveraging an existing IPC channel (via libjack), combined with a minimalistic set of changes to the server and easy-to-implement support in clients, to provide the basis for session management at different levels of sophistication, depending on a user's needs. Torben's example showed the generation of a shell script that will restart the session, and this is probably the "bottom line" in terms of simple session management. There are still some details (below) but more importantly, I would like to hear from people who have concrete objections, particularly of the following form: * the proposal does not address some functionality that it should address * the proposal will make later, more extensive session management harder, more complex or impossible * the proposal is nonsensical because ... As for details... I agree with the suggestion that the initial set of session events should include "quit". Nedko has also raised some objections to the use of a UUID, and has proposed a scheme based on PIDs. I personally do not understand how this can possibly work if JACK is to retain the ability to support multiple clients per process. Any scheme designed to use PIDs but still allow this seems to me to have to turn the PID into a UUID by combining it with some other information (eg. a client name). This doesn't seem to be semantically different from starting with a declaration that we use UUIDs to identify clients - how the UUIDs are constructed is an implementation detail. Finally, the semantics of the return codes from a session event need to be pinned down better, since there are circumstances where a client could *not* save its state without that being an error (e.g. ardour running with a session on read-only media). For this, I currently propose: success == client believes that it will be able to restore its state to the current state upon a reload fail = client believes that it will not (or may not) be able to restore its state to the current state upon a reload similar semantics will be needed for each other defined session event. _______________________________________________ Jack-Devel mailing list Jack-Devel(a)lists.jackaudio.org http://lists.jackaudio.org/listinfo.cgi/jack-devel-jackaudio.org