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From Jules Gosnell <>
Subject Re: Replication using totem protocol
Date Fri, 13 Jan 2006 10:41:01 GMT
inline at end...

Dain Sundstrom wrote:

> On Jan 12, 2006, at 12:28 PM, wrote:
>> I didn't see it - I'm not sure why.
>>> According to the website (
>>>      "Extended Virtual Synchrony for Java (EVS4J), an Apache-
>>> Licensed, pure-Java implementation of the fastest known totally
>>> ordered reliable multicast protocol."
>> Yes, I wrote that.
>>> Once you have a total ordered messing protocol, implementing a
>>> distributed lock is trivial (I can go into detail if you want).
>> Yes. You just send a totally-ordered message and wait for it to  arrive.
>>> I suggest we ask Guglielmo if he would like to donate his
>>> implementation to this incubator project
>> I don't know about donating it. Who would they want me to transfer the
>> copyright to?
> No.  You license the code to the Apache Software Foundation giving  
> the foundation the rights to relicense under any license (so the  
> foundation can upgrade the license as they did with ASL2).  We do ask  
> that you change the copyrights on the version of the code you give to  
> the ASF to something like "Copyright 2004 The Apache Software  
> Foundation or its licensors, as applicable."
>>> and if he would like to work on a pessimistic distributed locking
>> implementation.
>>> What do you think?
>> I would definitely like to work on it, but I still work for a  
>> living, so
>> that's something to think about. (I happen to be between jobs right  
>> now.)
> Nothing better to do between jobs than coding :)
>> Also, what do you need to locks for?
> Locking web sessions and stateful session beans in the cluster when a  
> node is working on it.


I see where you are coming from and it looks interesting. Virtual 
synchrony might well be useful in terms of guaranteeing lock-ordering 
etc., although at first glance, I have reservations about the 
scalability of multicast - but I need to read up on Totem...

I'll give Totem a mention it in the clustering doc that I am putting 


> -dain

"Open Source is a self-assembling organism. You dangle a piece of
string into a super-saturated solution and a whole operating-system
crystallises out around it."

 * Jules Gosnell
 * Partner
 * Core Developers Network (Europe)
 * Open Source Training & Support.

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