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From "Alex Ceponkus" <a...@ceponkus.org>
Subject RE: [jUDDI-developers] JavaUUIDGen
Date Wed, 23 Jan 2002 08:12:10 GMT
This scheme will wreak havoc with my ZoneAlarm. :)

I am interested in hearing about how it performs on Solaris.  Several years
ago I used to do sockets programming on top of Solaris and it took a
ridiculous amount of time (several minutes) to make a port available again.
Although we could easily get around that by just incrementing the port
number each time.  My guess is that I was just working on an old version of
Solaris and it's probably fixed by now.

-----Original Message-----
From: juddi-developers-admin@lists.sourceforge.net
[mailto:juddi-developers-admin@lists.sourceforge.net]On Behalf Of Bob
Hablutzel
Sent: Wednesday, January 23, 2002 8:44 AM
To: Maarten Coene; juddi-developers@lists.sourceforge.net
Subject: RE: [jUDDI-developers] JavaUUIDGen


Maarten -

    The basic idea was to use a system resource that imposes locking
semantics, since Java doesn't provide direct access to low-level system-wide
locking constructs. So, for example, a TCP/IP port can only be bound by one
thread of execution at once; a file can atomically be created if it didn't
exist, and so forth.
    The implementation I was working on used server sockets as the locking
mechanism. It looks something like this:

	obtain lock:		ServerSocket lock = new ServerSocket( 8090 );
      release lock:           lock.close(); lock = null;

    So far, it's worked on both NT and Linux; I can test it under Solaris in
a day or so. Interestingly, the latency isn't bad at all. I was worried
about the reopen time-out of TCP ports, but that seems to only apply only if
you actually accept connections. Since the lock only requires a bind (which
is system-wide locking), you can obtain pretty good lock performance.

    Let me know if you want me to code this up further, or if you have any
other comments.

take care,

hab


-----Original Message-----
From: juddi-developers-admin@lists.sourceforge.net
[mailto:juddi-developers-admin@lists.sourceforge.net]On Behalf Of
Maarten Coene
Sent: Wednesday, January 23, 2002 3:29 AM
To: Bob Hablutzel; juddi-developers@lists.sourceforge.net
Subject: RE: [jUDDI-developers] JavaUUIDGen


sounds interesting, and it seems a good idea since you'll probably get 2
equal UUIDs when you call the nextUUID() method at the same time twice on
the same node (since the time and the ethernet address are the same)

Maarten

At 20:15 22/01/2002 -0500, you wrote:
>Maarten - I was just starting to look at putting in place a global locking
>mechanism to ensure that you never got duplicate UUIDs on a node. If you
>want to talk about the idea I had, it would be pretty quick to implement -
>drop me a note.
>
>hab

--
Maarten Coene
Katholieke Universiteit Leuven
Dept. Computerwetenschappen             Tel: ++32 (0)16/32 78 25
Celestijnenlaan 200A
B-3001 Heverlee



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