[jboss-jira] [JBoss JIRA] (WFLY-5369) Wildfly doesn't handle @Resource name attribute for DataSource type

[Jason Greene (JIRA)]

    [ https://issues.jboss.org/browse/WFLY-5369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13110594#comment-13110594 ] 

Jason Greene commented on WFLY-5369:
------------------------------------

Hi Ivn,

If you declare a @Resource without a lookup (or mappedName), then the JNDI name it resolves is either defined by a deployment descriptor or its set to one of the EE7 defined default resource. So in this case its “java:comp/DefaultDataSource” per EE 5.1.9. The spec also requires that duplicate @Resource declarations (specify the same name in the same namespace) by validated to be identical and error if not (EE 5.2.2 "If all attributes of each declaration of a shared environment entry are not identical, this must be reported as a deployment error to the Deployer. "). This is the case since they effectively specify different names. Now technically with our stock config those names both resolve to the same underlying resource, so we could be smarter and specially handle that case, but if the default data source does not match the resource in the class annotation the error would then still occur. In short, this is not a portable approach to aliasing annotation declarations, and is precisely what the lookup= attribute is for.

Now as to why it works with Object is a side effect specific to our implementation. Name binding and field injection are distinct processes, and the use of Object means there is no provider available to run the binding portion, yet the lookup portion still runs. The lookup portion uses the names created by the binding portion. This is undefined territory though so I would not rely on it.

As to why this works on other container vendors, the spec allows a lot of freedom there, so they may infer the binding in some cases, although being non-standard you may not be able to rely on the consistency of that behavior. As to why the EE6 tutorial works, the expectation was likely that the unbound entry would have been defined/configured either on the server or via a DD.

> Wildfly doesn't handle @Resource name attribute for DataSource type
> -------------------------------------------------------------------
>
>                 Key: WFLY-5369
>                 URL: https://issues.jboss.org/browse/WFLY-5369
>             Project: WildFly
>          Issue Type: Bug
>    Affects Versions: 9.0.1.Final
>            Reporter: Ivn Lahav
>            Assignee: Jason Greene
>             Fix For: No Release
>
>
> When using {{@Resource}} with {{name}} attribute to inject an object from environment naming context (ENC) into a servlet or EJB, Wildfly is producing an error.
> Here is an example from injecting into Servlet (the same is with injecting into EJBs).
> First the part that does work:
> {code}
> @WebServlet(loadOnStartup=1)
> @Resource(name="db1", lookup="java:jboss/datasources/ExampleDS", type=DataSource.class)
> public class Servlet1 extends HttpServlet {
>         @PostConstruct
> 	public void init0() throws Exception {
> 		System.out.println("___________db1: " + InitialContext.doLookup("java:comp/env/db1"));
> 	}
> }
> {code}
> So we can see that the ENC entry {{db1}} is properly defined and can be looked up.
> Now we  add a field to the above class and use {{@Resource}} injection:
> {code}
> @Resource(name='db1')
> DataSource ds;
> {code}
> we get the this error:
> {code}
> Caused by: java.lang.IllegalArgumentException: WFLYEE0047: Incompatible conflicting binding at java:module/env/db1 source: lookup (java:jboss/datasources/ExampleDS)
> 	at org.jboss.as.ee.component.deployers.ModuleJndiBindingProcessor.addJndiBinding(ModuleJndiBindingProcessor.java:221)
> 	at org.jboss.as.ee.component.deployers.ModuleJndiBindingProcessor$1.handle(ModuleJndiBindingProcessor.java:183)
> 	at org.jboss.as.ee.component.ClassDescriptionTraversal.run(ClassDescriptionTraversal.java:54)
> 	at org.jboss.as.ee.component.deployers.ModuleJndiBindingProcessor.processClassConfigurations(ModuleJndiBindingProcessor.java:187)
> 	at org.jboss.as.ee.component.deployers.ModuleJndiBindingProcessor.deploy(ModuleJndiBindingProcessor.java:144)
> 	at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:156)
> 	... 5 more
> {code}
> Interestingly, if I change the data type of a field from {{DataSource}} to {{Object}}, things start working.
> This is a very basic functionality of Java EE and we are using it extensively to produce vendor independent deployment units that directly reference only logical ENC entries and not physical vendor specific JNDI names. Then during deployment the administrator would customize the mapping to match the application server and a specific environment.



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