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POHow do I override the value supplied to a field annotated with @EJB?
 

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  1. POHow do I override the value supplied to a field annotated with @EJB?
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    <p>Suppose I have a class like this:</p> <pre><code>@Stateless @Local({ X.class }) public class XBean implements X { @EJB // name() attribute should by spec default to "foo.XBean/y", but see below private Y y; // Y is @Local } </code></pre> <p>And elsewhere I have:</p> <pre><code>@Stateless @Local({ Y.class }) public class YBean implements Y {} @Stateless @Local({ Y.class }) public class UnwantedYBean implements Y {} </code></pre> <p>Suppose now I want (in an XML descriptor, using the minimal amount of XML) to override or explicitly specify what gets placed in the <code>y</code> field in <code>XBean</code>.</p> <p>This construct (in a <code>META-INF/ejb-jar.xml</code> file, of course) surprisingly (to me) does <em>not</em> work in GlassFish 3.1.2.2:</p> <pre><code>&lt;ejb-jar&gt; &lt;enterprise-beans&gt; &lt;session&gt; &lt;ejb-name&gt;XBean&lt;/ejb-name&gt; &lt;ejb-local-ref&gt; &lt;ejb-ref-name&gt;foo.XBean/y&lt;/ejb-ref-name&gt; &lt;ejb-link&gt;YBean&lt;/ejb-link&gt; &lt;/ejb-local-ref&gt; &lt;/session&gt; &lt;/enterprise-beans&gt; &lt;/ejb-jar&gt; </code></pre> <p>I'd like to focus this question on the <code>ejb-jar.xml</code> snippet above, not on any container bugs or anything like that. Specifically: <strong>is the above snippet the correct and the smallest possible way to override what EJB gets injected into my <code>XBean.y</code> field?</strong></p> <p>Some notes:</p> <ul> <li><p>Others have suggested that I need to put an <code>&lt;injection-target&gt;</code> stanza in there. Why would that be? The injection target is already specified by virtue of my using the <code>@EJB</code> annotation. I don't wish to override where the injection occurs, only what actually gets injected.</p></li> <li><p>The EJB specification author herself also said that the <code>&lt;ejb-ref-name&gt;</code> should be simply <code>y</code>, not <code>foo.XBean/y</code>. This is despite the fact that the specification says (section 16.5.1.3):</p></li> </ul> <blockquote> <p>The ejb-ref-name element specifies the EJB reference name: <em>its value is the environment entry name used in the enterprise bean code</em> [emphasis mine].</p> </blockquote> <ul> <li><p>There is nowhere in the EJB specification that says what the default value of the <code>name</code> attribute is for the <code>@EJB</code> annotation (!), but we can infer that it is also the environment entry name. </p> <p>The spec gives an example in section 16.5.1.1:</p></li> </ul> <pre><code>package com.acme.example; @Stateless public class ExampleBean implements Example { ... @EJB private ShoppingCart myCart; ... }</code></pre> <p>...which is exactly equal to mine, and then says in the same section (this is as close as we'll get to discovering what the default value for <code>@EJB</code>'s <code>name</code> attribute is):</p> <blockquote> <p>The enterprise bean reference will have the name <code>java:comp/env/com.acme.example.ExampleBean/myCart</code> in the referencing bean’s naming context, where <code>ExampleBean</code> is the name of the class of the referencing bean and <code>com.acme.example</code> its package.</p> </blockquote> <p>The "naming context" in that sentence is the <code>java:comp/env/</code> part, so everything else is the name, so the default value of an unadorned <code>@EJB</code> annotation's <code>name</code> attribute is <code>classname/fieldName</code>. I don't see how this could be otherwise. This is also backed up by the table present in <a href="https://glassfish.java.net/javaee5/ejb/EJB_FAQ.html" rel="nofollow">the GlassFish EJB FAQ</a>.</p> <p>Bottom line: <strong>what is wrong with my XML stanza cited above?</strong> Why does it not cause a proxied instance of <code>YBean</code> to be injected into my <code>XBean</code>'s <code>@EJB</code>-annotated <code>private Y y</code> field?</p>
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    1. COHave you tried CDI ways to deactivate the EJB? E.g. defining an @Alternative by subclassing YBean?
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    2. CODid you ever solve this? I'm in the same situation and would have written exactly the same ejb-jar.xml. It works like that if both EJB implementations as well as the ejb-jar.xml are in the same .jar, but it fails as soon as I split them into two separate ejb jars and want to choose one of the implementations within the web app's ejb-jar.xml. Example code here: https://github.com/tknerr/sample-ejb-app
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    3. CO**UPDATE: it works now -- in both cases! The trick was to use the EAR's application.xml for the latter case** See README and example code from the link above
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