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POMultiple instances of EJB 3.1 no-interface Singleton / Stateful session bean
 

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  1. POMultiple instances of EJB 3.1 no-interface Singleton / Stateful session bean
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    <p>I want to access multiple instances <code>singletonA</code> and <code>singletonB</code> of a no-interface Singleton <code>MySingleton</code>. The instances are first defined in another Singleton <code>Configurator</code> class:</p> <p><strong>MySingleton.java</strong></p> <pre><code>@Singleton @LocalBean public class MySingleton { ... } </code></pre> <p><strong>Configurator.java</strong></p> <pre><code>@Singleton @Startup @LocalBean public class Configurator { @EJB MySingleton singletonA; @EJB MySingleton singletonB; } </code></pre> <p>The code above, appearently works.</p> <p>Now, I need to inject these 2 instances of MySingleton in a Message-Driven Bean:</p> <p><strong>MDB.class</strong></p> <pre><code>@Stateless public class MDB implements MessageListener { @EJB (lookup="?") MySingleton singletonA; @EJB (mappedName="??") MySingleton singletonB; } </code></pre> <p>But at this point I am completely lost. I know that I could make things simpler by defining the 2 instances as 2 (empty) implementations of a unique interface. But I have some problems because the class contains some non static fields, so I can't define it as an Interface.</p> <p><strong>EDIT</strong></p> <p>Because of the nature of MDB, I can't pass the Singletons by reference. Finally, I would like to avoid creating two identical implementations of MySingleton.</p> <p>Thanks to the answers received I have been rethinking at the whole architecture and I must agree on the fact that having MySingleton defined as Stateful would be fine as well.</p>
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    1. COBased on edit: Singletons are generally very different from a Stateful, but they match Stateless beans better. May be you can consider this fact when you redesign your application. Stateless and Singleton both work on a request basis(in general) and do not maintain state.
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