>> Also, how can the EJB container achieve this? Would
>> this imply that to have entity bean failover all
>> entity beans would have to be replicated across the
>> containers? What would be the implication of such
>> replication on concurrent access to the entity beans?
>
>The EJB container achieves that by reloading that entity bean on the
>other server. It may, or may not, and that might depend on the bean (and
>certainly the EJB container) replicate the entity bean. If your entity
>bean simply holds information retrieved from the database, just
>reloading it on the other server will do the trick.
>
>arkin
Surely there is a lot assumed here of the app server and/or database
replication . I am not aware of how specific app servers might implement CMP
entity bean replication, but if your failing over because a power spike took
out the machine on which your database runs, you have to have database level
replication as well don't you ?
How much can realistically be expected of an application server on the CMP
entity bean replication front if you assume you want to tolerate hardware
failure of the database server ?
Failing over to a new app server instance where the underlying database is
assumed to still exist doesn't seem that hard, but if you want failover to
also tolerate loss (or failover) of the underlying database, it seems like
it would be a lot harder, or at least vendor specific, to me. I'd love to be
surprised otherwise.
thanks,
matthew
| j. matthew pryor <mailto:[EMAIL PROTECTED] >
| verve, inc. <http://www.verveinc.com/>
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