Re: [eclipselink-users] Virtual Metlhods | questions

[Tom Ware <tom.ware@xxxxxxxxxx>]

Hi Gaurav,

  I am assuming you've figured out how to get refreshMetadata to work for you 
to get your mappings added.  EclipseLink itself does not provide a mechanism to 
trigger the refresh  There are a number of options open to you depending on how 
your app is architected, JMS, RMI, ServerSentEvents, WebSockets, Oracle QCN/DCN 
combined with one of those technologies.

  The way refreshMetadata works, should allow your system to stay live.  When 
you call refreshMetadata, all existing EntityManagers continue to operate on the 
previous metadata.  The new metadata is only in effect for new EntityManagers.

-Tom

On 24/07/2012 8:12 PM, gaurav malhotra wrote:
> I understand the problem, but I don't know how to fix it.
> 1) I am recording all the changes (we store them in the database)
> 2) I don't know how to signal that session needs to pick them using
> refreshMetadata. Does this mean using SessionEventAdapter?? If yes then which
> method(s) should I use. As per my understanding refreshMetadata should be only
> called once if there are recorded changes. When recorded changes has been pushed
> to session, then there is no need to refreshMetadata. It will be great if you
> point me some code snippets.
>
> Also, my product, is a claim processing system (with millions of transactions
> handled in a day). What is the impact of refreshMetadata on the running
> transactions?? We dont expect setup for the dynamic fields change every another
> minute or a day??
>
> On 25-07-2012 12:04 AM, Christopher Delahunt wrote:
> > Through a metadata source repository, or the customizer approach. Your app
> > must record the changes that are needed somehow and then signal that the
> > session needs to pick them up using refreshMetadata. The app should not
> > directly change the running session.
> >
> > On 2012-07-24, at 5:47 PM, gaurav malhotra <gaurav.malhotra@xxxxxxxxxx> wrote:
> >
> > > Hi Chris,
> > > It's the requirement of my product - Dynamic Fields can be configured at the
> > > runtime and should be picked up in live application with zero down time. Its
> > > for the dynamic fields I am creating the mappings.
> > > How to accomplish above reqirement?
> > >
> > > ~Gaurav
> > > On 24-07-2012 11:29 PM, Christopher Delahunt wrote:
> > > > This would occur if the mapping has not been initialized; initialization
> > > > occurs during session login. Earlier posts showed mappings being added
> > > > through a session customizer which get called prior to login. How and when
> > > > is this mapping added?
> > > >
> > > > Calling refreshMetadata as Tom mentions creates a new session from the
> > > > metadata, and would call customizers on it before logging in. If your
> > > > customizer picks up the new mapping changes, then that might explain why it
> > > > works for you, since they get initialized with the new session login.
> > > >
> > > > It is not a good idea to make mapping/descriptor changes to active sessions
> > > > after login has occurred.
> > > >
> > > > On 24/07/2012 5:05 PM, gaurav malhotra wrote:
> > > > > ava.lang.NullPointerException
> > > > > at
> > > > > org.eclipse.persistence.mappings.ForeignReferenceMapping.valueFromRowInternal(ForeignReferenceMapping.java:2019)
> > > > >
> > > > >
> > > > > at
> > > > > org.eclipse.persistence.mappings.ForeignReferenceMapping.valueFromRow(ForeignReferenceMapping.java:1987)
> > > > >
> > > > >
> > > > > at
> > > > > org.eclipse.persistence.mappings.ForeignReferenceMapping.buildCloneFromRow(ForeignReferenceMapping.java:276)
> > > > >
> > > > >
> > > > > at
> > > > > org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildAttributesIntoWorkingCopyClone(ObjectBuilder.java:1548)
> > > > >
> > > > >
> > > > > at
> > > > > org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildWorkingCopyCloneFromRow(ObjectBuilder.java:1694)
> > > > >
> > > > >
> > > > > at
> > > > > org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObjectInUnitOfWork(ObjectBuilder.java:664)
> > > > >
> > > > >
> > > > > at
> > > > > org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:601)
> > > > >
> > > > >
> > > > > at
> > > > > org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:560)
> > > > >
> > > > >
> > > > > at
> > > > > org.eclipse.persistence.queries.ObjectLevelReadQuery.buildObject(ObjectLevelReadQuery.java:717)
> > > > >
> > > > >
> > > > > at
> > > > > org.eclipse.persistence.queries.ReadAllQuery.registerResultInUnitOfWork(ReadAllQuery.java:769)
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