Re: DO behavior depends on server launch
Re: DO behavior depends on server launch
- Subject: Re: DO behavior depends on server launch
- From: email@hidden
- Date: Tue, 31 May 2005 23:37:24 +1000
As a related question, the documentation for NSConnection and
NSMachPort
appear to imply that connections are specific to a *host* but I
have not
been able to get my client and server apps to communicate unless
they are
both running under the same Unix user id. Is this the expected
behavior?
This is unfortunately a documentation issue. Every user "session"
has a difference Mach namespace, and you can only use NSMachPort's
within a single namespace. SSH creates a new "session", even if it's
the same user as is logged in locally. I suspect you also have two
different sessions for two different SSH connections, although I've
never tested that scenario.
If you need more flexibility, your only option at present is to use
sockets. Back in the NeXTStep days - I'm told; I ain't that old ;) -
you could communicate using Mach between machines... I'm not sure how
the namespaces figured into that, whether you didn't have them at all
or there was a mechanism for inter-space communication, but in any
case all that functionality has been stripped out of MacOS X (no, I
don't know why either... I also don't know why in four major OS
revisions Apple haven't fixed at least the documentation issues with
DO, if not the implementation ones... but I rant...).
Performance of sockets shouldn't be too much less than mach ports -
Unix domain sockets are the defacto way of doing IPC like this on non-
Mach systems, so they're designed to be very fast. There are
additional security issues though, since you can no longer be 100%
sure you're only talking to the local machine... if you need that
sort of assurance you'd need to do some extra checks (e.g. on each
socket's remote address, etc).
Wade Tregaskis (AIM/iChat, Yahoo & Skype: wadetregaskis, ICQ:
40056898, MSN, audio/video iChat & email: email@hidden,
Jabber: email@hidden)
-- Sed quis custodiet ipsos custodes?
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