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    <p>It is quite possible for the <code>@PreDestroy</code> method to not be invoked. The EJB 3.1 specification, explicitly states this:</p> <blockquote> <p><strong>4.6.3 Missed PreDestroy Calls</strong></p> <p>The Bean Provider cannot assume that the container will always invoke the PreDestroy lifecycle callback interceptor method(s) (or ejbRemove method) for a session bean instance. The following scenarios result in the PreDestroy lifecycle callback interceptor method(s) not being called for an instance:</p> <p>• A crash of the EJB container.</p> <p>• A system exception thrown from the instance’s method to the container.</p> <p>• <strong>A timeout of client inactivity while the instance is in the passive state.</strong> The timeout is specified by the Deployer in an EJB container implementation-specific way.</p> </blockquote> <p>The specification also details how resources may be removed if the <code>@PreDestroy</code> method is not invoked in such scenarios:</p> <blockquote> <p>For example, if a shopping cart component is implemented as a session bean, and the session bean stores the shopping cart content in a database, the application should provide a program that runs periodically and removes “abandoned” shopping carts from the database.</p> </blockquote> <p>In your case, it would depend on how you are storing the state of your reservations. If they are persisted in the database, then I would suggest employing the same approach as mandated in the specification. You could use the EJB Timer service, to perform this activity periodically, or use a scheduler like Quartz. Note, that it is imperative to distinguish between the contents of passivated session bean instances that no longer exist, and those that will be made ready once again.</p>
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    1. COThanks for the detailed answer. I'd be very grateful if you could help me with another small question. In case the bean is deleted while being passivated, the client's session still have a reference to the deleted bean. Could you please show me how I can detect that the bean has been deleted?
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    2. COYour question - `Could you please show me how I can detect that the bean has been deleted?` implies that it is possible to detect, when in fact it is impossible for a client to do so. The stateful session bean is created and managed by the container. The client only has a proxy reference to it. If you need to handle this scenario, you must catch the `NoSuchEJBException` exception that could *possibly be thrown* on every method invocation, and attempt to create a new instance of the bean.
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    3. COThanks a lot for the help!
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