Paul,
Your questions answered below...
Paul writes:
> -----Original Message-----
> Chris Raber wrote:
>
> > You just described GemStone/J's PCA "to a tee".
>
> Even though this may be vendor specific, how does this all work
> in a clustered environment? Are the object caches in each
> container kept consistent across multiple container instances?
> If so, how is it done - what are the limitations?
>
First, GemStone/J has a multi-JVM architecture, whether on one phsyical
machine or distributed. The "container" doesn't exist physically per se, but
is rather a logical construct (one could view the container as the sum of
the parts).
Each JVM has multiple windows or GsSessions into the cache (kind of like a
JDBC connection is to an RDBMS). Each session has a transactional view of
the state of the cache. Changes to cached objects are performed in
transactional isolation. The transactional manager provides for synchronized
updates to cache and RDBMS with acid transaction semantics.
Remote caches do write-through cache synchronization. Remote caches are
synched as required at transaction boundaries (rather than broadcasting
changes everywhere at every udpate).
Limitations are that network traffic is required to synch caches, and for
transaction updates to the server where the cache is persisted. So high
bandwidth connectivity within the cluster is the ideal (i.e. fddi rings...).
> If not, what can be done to take advantage of EJB object
> caching in a clustered environment? Are there any clustered
> caching implementations available?
>
Again, this is what GemStone/J offers.
> Thanks,
> -Paul Hodgetts
>
PS: It took many years for GemStone to build the core technology in this
architecture. This is not a weekend project or a grad student thesis!
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