Hi,
the best way to achieve this goal, "pushing an event to a
client", is to use JMS. Let your clients be JMS subscribers
to a JMS Topic, and let your EJB send "change events"
to this Topic. Using JMS is the standard way for an EJB
component to send asynchronous messages.
Best Regards,
François
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Francois EXERTIER Evidian (Groupe Bull)
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Steven Owens wrote:
> Hi,
>
> I'm sure this is going to sound odd, but is there any way for an
> entity bean to push an event to a client?
>
> Suppose I have a large hunk of data - say an XML DOM - that a lot
> of my servlets are going to want to get their hands on. However, the
> servlets may also need to change the data. I see two obvious
> approaches:
>
> keep the data in an entity bean and encapsulate the data with
> accessors to perform the necessary operations on the data,
>
> provide a remote method that pulls the large chunk of data down
> and have the servlet request the entire data, use it, and
> if necessary make changes, and push the changed version back.
>
> Neither of these quite works for my needs. The first approach
> the EJB standard approach (if I understand EJb correctly) but it
> assumes a static or at least fairly stable application. The second
> approach involves huge amounts of network latency and serialization/
> deserialization overhead for each request.
>
> An alternative that occurs to me is to have a singleton client
> that lives in each servlet JVM and fetches the data, keeps a copy on
> hand, and hands out references to it(*).
>
> The client singleton would have to check with the EJB constantly
> to make sure it has up to date data, and flush changes immediately
> back to the EJB. This would probably be sufficient, but it'd be even
> niftier to have some way to push change events from the EJB out to the
> client. Is this possible?
>
> (* With a complex data structure - a set of objects, - the servlets
> would, of course, have to be careful not to hang onto references
> that might become stale, but that's true for any of these
> approaches. I don't see any way around this isssue).
>
> Steven J. Owens
> [EMAIL PROTECTED]
>
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