By default remote interface invocations use pass by value, as required by the EJB specification. This element can be used to enable pass by reference, which can give you a performance boost. Note that WildFly will do a shallow check to see if the caller and the EJB have access to the same class definitions, which means if you are passing something such as a List<MyObject>, WildFly only checks the list to see if it is the same class definition on the call and EJB side. If the top-level class definition is the same, JBoss will make the call using pass by reference, which means that if MyObject or any objects beneath it are loaded from different class loaders, you would get a ClassCastException. If the top-level class definitions are loaded from different class loaders, JBoss will use pass by value. JBoss cannot do a deep check of all of the classes to ensure no ClassCastExceptions will occur because doing a deep check would eliminate any performance boost you would have received by using call by reference. It is recommended that you configure pass by reference only on callers that you are sure will use the same class definitions and not globally. This can be done via a configuration in the jboss-ejb-client.xml as shown as follows.

To configure a caller/client use pass by reference, you configure your top-level deployment with a META-INF/jboss-ejb-client.xml containing:

<jboss-ejb-client xmlns="urn:jboss:ejb-client:1.0">
    <client-context>
        <ejb-receivers local-receiver-pass-by-value="false"/>
    </client-context>
</jboss-ejb-client>