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From Jules Gosnell <>
Subject Re: [wadi-dev] Re: Clustering - WADI/ActiveSpace Synergy...
Date Mon, 30 Jan 2006 10:29:58 GMT
James Strachan wrote:

> On 30 Jan 2006, at 10:06, Jules Gosnell wrote:
>> Finally, as discussed with James on numerous occasions, we should  
>> look at how WADI's pessimistic locking and PartitionManager might  be 
>> componentised so that they can be plugged into AS to provide  Cache 
>> and Space users, who are not interested in location- independance, 
>> with a pessimistic approach and/or a partitioned  clustering 
>> substrate...
> BTW I don't see using a pessimistic lock as being very useful for a  
> cache; typically in a JCache scenario you are caching state that is  
> stored in some database/system; so if you really want a pessimistic  
> lock you should lock the database (they are very good at doing  
> distributed locks) rather than having a pessimistic lock in a cache  
> which is a different lock to where the actual data is.

Agreed - but in the case of a distributed session, it may not be mapped 
to a database.... - I guess we are not a typical JCache scenario ?

> Optimistic  locks are much more efficient & useful in a distributed 
> caching  system (which is why we implemented them in ActiveSpace).

> Though using the PartitionManager as a way of implementing a sparse  
> cache is a good endevour. Incidentally ehcache has support for  
> distributed caching now...

I will revisit it ...

> Maybe we can persuade the ehcache team to adopt the JCache API and  
> plug in any distributed strategies or sparse caching strategies into  
> that. (ActiveSpace was using the RI of JCache which is less  
> functional than ehcache)

Sounds like an idea :-)


> James
> -------

"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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