Re: determine file is local?

allan wrote:


     How local is "local?"

     If there are disks physically inside the same box as your
CPU, memory, and power supplies, I imagine you would call them
"local." But what about disks in a separate box sitting in the
same rack, with their own independent power supplies, connected
via SCSI cable to an adapter plugged into your machine's backplane?
Are they "local?" What if the disk box also holds a hardware RAID
controller, so your machine never talks to the disks themselves
but only to the controller? What about disks in a SAN sitting
ten meters away from your machine and only communicating with it
through a bunch of fibre switches? What about NAS? What about ...?

     Or let's take another tack. Assume you have settled upon a
satisfactory definition of "local," and consider an application
that starts at net.null.allans.AllansApplication#main, but that
also uses com.cartalk.utilities.DeweyCheathamAndHowe. Suppose
the AllansApplication class is loaded from a class file or JAR
on a "local" disk, but that the DeweyCheathamAndHowe class comes
from a "remote" disk also found on the CLASSPATH. Now: is the
application as a whole "local" or "remote?"

     You need to take a step back and consider not how to answer
this foggy and ill-defined question, but why you are asking it
in the first place. What are you trying to find out -- that is,
how do you want the answer to change the application's behavior?

--
Eric Sosman
esosman@acm-dot-org.invalid