Re: Running Cocoa applications from file servers
Re: Running Cocoa applications from file servers
- Subject: Re: Running Cocoa applications from file servers
- From: "I. Savant" <email@hidden>
- Date: Wed, 25 Feb 2009 13:54:19 -0500
On Wed, Feb 25, 2009 at 1:16 PM, Kyle Sluder <email@hidden> wrote:
> How so? Resource loading? I guess it was less of an issue back in
> the NeXT days. But I've got ten machines in my lab, and an Xserve
> serving out /Network/Library... why can't I use /Network/Applications
> and have it Just Work(TM)?
Well, see my last response for the general overview of my reasoning.
For specifics, though, consider that your setup is not the only
network topology.
Imagine a complicated app with many resources (its UI divided up
into many nibs like Mail.app, and different sounds and plug-ins,
etc.). To mitigate this problem so that it "just works" (as long as
you can initially launch the application successfully), the
application would have to load *everything*, which obviates most of
the benefit of separating things into separate nibs, loading them only
when needed. Obviously, this is even less desirable on a larger app
that's being loaded over the network (loading everything takes
longer).
> I'm not all that worried about network interruptions.
Must be nice. ;-) Even in the simplest topologies, they happen, so
you *should* be ...
Imagine a more complicated network topology. Many business and other
institutions are larger and more complicated. The application server
might be centrally managed by corporate headquarters, which may or may
not be where you are. "We pay top dollar for the fastest
point-to-point connections, so it'll load plenty fast," they say. What
they don't think of are interruptions and they certainly don't tend to
test even business-critical applications for robustness in this
scenario ... how many man-hours are lost if the app fails ungracefully
and whacks important data?
More than that, though, are sprawling LANS with old equipment or
power problems. Wireless networks which are prone to interference.
Network interruptions *happen*, so while one network might be
reliable, it's been my experience in the many business and institutes
I've worked for that most aren't 100%.
There's no planning for the many kinds of network environments on
which your apps may be run, but you can at least plan for plenty of
those environments being unreliable. In this case, your only choice is
to load every resource the app needs at launch, or over-engineer the
hell out of the app so that it intelligently handles every possibility
that can arise from a resource not being available at runtime (and
deciding whether it's safe to save data in that state, etc).
Personally, my previous employers were an engineering firm who ran
*everything* from the server. Apps, home folders, the works. A screwed
up server installation (which the admin team refused to accept and
handle for weeks) ended up corrupting drawings, losing business
documents, and more until tens of thousands of dollars of man-hours
were wasted and deadlines were missed. With sufficient screaming from
management, the problem was fixed, but it highlighted the dangerous
nature of the problem.
Lessons learned:
- Use portable home folders, rather than server-hosted home folders.
- Install apps locally since many of them freaked the hell out when
they couldn't load resources all the sudden, disallowing even a local
save to their machine.
- When your server(s) are everything, don't let them get so bad they
bring down the whole f*****g company!
- Even software developers can point out specific OS issues for the
admin team ... ;-)
Put simply, yes, there are other problems caused by intermittent
network outages, but like those other problems, there're no simple
solutions. You always sacrifice convenience for safety or the other
way around. In this case, you can load all your resources or
over-engineer the app to handle every 'missing resource' situation
perfectly.
--
I.S.
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