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Struts & Hibernate
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| | | data replication | data replication 2004-07-12 - By Rajesh Mittal
Back
Hi,
Since you are using web sphere for development. web sphere must have the
support to handle
these kind of scenarios. Try to find a solution on IBM site or in the
websphere docs.
otherwise, you can think in terms of following solution. But I am not sure
how far will this be helpful to
you.
since you are connected to a single database and having multiple EJB
servers running the
same schema. You need to have a distributed cache invalidation so that if
any data change
occurs in any EJB servers, that can be propagated to other servers allowing
them to refresh
their data. This can be achieved using JMS. i.e. Have a centralized
server and let all the
other EJB servers register with the JMS server. whenever a transaction is
being carried
out, a asynch message is sent to this JMS server and JMS distributes that
message to other EJB servers.
This message contains what's got changed in DB. so that other EJB servers
can go to db and update
their information in the cache or whenever accessed.
Does it make sense ?
Rajesh
At 13:03 12/07/2004, koala.gnu@(protected) wrote:
>I have a server with a connected DB. I want use 2 or more servers with
>same DB schema.
>If a change occurs on a server (cache or DB) I want replicate this change.
>I do not know if this is a Master/Master or
>Master/Slave. The question is: does EJB do this job? If so, Should I delegate
>this to DB. In this case I think that different implementation should occur
>for each type of DB. Am I right?
>
>As reported below. I have also problem in understand how to implement sequence
>pattern for key generation in a clustered env and if it is possible execute
>specific services on only one server in a cluster. For example, If I should
>aggregate some data using a periodical thread I want to do this on only
>one server and then replicate the result on others server.
>
>Is this possible?
>
>PS
>
>I am using websphere.
>
>
>
>
>
>
>
>-- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- -----
-- ---- ----
>Hi,
>
>what kind of data replication are u talking about ?
>is there two master databases with which your applications are going to
>talk.
>or a master or slave type of db architecture..
>
>what EJB's or other mechanism can do is to refresh their references/cache
>when some record is updated in db by an application running in other cluster.
>
>so if you can provide more info, we might be able to help you.
>
>Rajesh
>
>At 12:11 12/07/2004, koala.gnu@(protected) wrote:
>
> > Hi all,
> >
> > some questions.
> >
> > 1) Suppose I have a J2EE application with
> >
> > WEB Tier
> > EJB Tier
> > Database Tier
> >
> > I want to use clustering for solve scalability problem but I do not know
> > who should be responsible for data replication: EJB or DB?
> >
> > I mean if on two server I configure EJB layers in clustering, does this
> > allow data replication?
> > If so, the entity bean should be defined remote or local. Currently I
>use
> > only local interface since session bean access to them on same JVM.
> >
> > 2) I use sequence bean pattern for id generation, but how to implement
>it
> > in a clustered environment. Any link?
> >
> > 3) again. I have some periodical tasks (call them services) and I want
>execute
> > them only on one server. It could be a good choice distribute service
> > execution
> > on server. What pattern I should use?
> >
> > Thanks.
> >
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>
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