Matt Benson wrote:
--- Steve Loughran <[EMAIL PROTECTED]> wrote:
Peter Nabbefeld wrote:
Hello,
I've asked this question on the users list, but it
seems nobody knows
there:
Is it possible to create two java processes (with
fork="true") and pipe
the output of one process into the other?
Not yet :)
Ant1.6.2 added the notion of the ioredirector to
exec and java, but no
direct coupling of apps. You'd have to write your
own filter to route
the stuff...and ant equivalent of Unix named pipes
Yep. To let my own proverbial (dead) cat out of the
bag,
Schoedinger says the cat is only dead or alive when you open the bag
this was one of my original goals when I exposed
the redirector functionality. After committing the
current functionality, I had added the additional
concept of an (input|output|error)ref attribute:
inputref would specify a reference to an inputstream
from which input should be read; (output|error)ref
would specify a reference to an inputstream from which
another process could read, created using a
PipedOutputStream->PipedInputStream (actually an
oata.util.LeadPipeInputStream) set. Concurrency
issues were solved by a ProxyInputStream class; while
locking at the Redirector class level (no new stream
references added), the Project would be probed for the
named InputStream. If none were found, a
ProxyInputStream would be created that would continue
to search for the (literally) "named pipe". This all
worked like a charm...
...on Unix (Solaris, I like to think it probably would
have worked on other Unix systems). I could not for
all the world convince the stupid Windows JREs not to
deadlock on any but the simplest uses of this. I have
since lost that bit of code, but could re-create if
any Threading gurus want to take a stab at it.
-Matt
Interesting design. I would have done a <namedpipe id="" /> datatype
that did the synchronisation; producers and consumers would sync by
choice of pipename. But like you say, the problem becomes process
co-ordination; handling failures and propagating them gracefully, or
just how to keep processes around until their consumer/producer was
there. This is the stuff we normally delegate to the OS, or, for
distrubution, to some message queue. Though named pipes work across
clusters, at least on the apollo and hpux cluster systems.
-steve
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