Hi John, No it shouldn't. The problematic and confusing case would be when there is some other param (injection point) in this observer method and this param resolves to let's say @SessionScoped bean. How does it work then? Once it fails (since there's no context propagation for async event), once it works (sync event)? Therefore this was forbidden. Tom ----- Original Message ----- From: "John Ament" <john.ament(a)spartasystems.com&gt; To: "cdi-dev" <cdi-dev(a)lists.jboss.org&gt; Sent: Monday, March 6, 2017 1:42:09 AM Subject: [cdi-dev] Can an observer be both async and sync? Section 10.4.4 has the following section which got me thinking public void refreshOnDocumentUpdate(@Observes(notifyObserver=IF_EXISTS) @Updated Document doc) { ... } public void asyncRefreshOnDocumentUpdate(@ObservesAsync(notifyObserver=IF_EXISTS) @Updated Document doc) { ... } I'm wondering, is it OK to have an observer method defined like this? public void asyncRefreshOnDocumentUpdate( @Observes(notifyObserver=IF_EXISTS) @ObservesAsync(notifyObserver=IF_EXISTS) @Updated Document doc) { ... } I don't see anything against this in the spec, but I suspect most people are going to think this shouldn't work. So I'm asking the question - should it work? John NOTICE: This e-mail message and any attachments may contain confidential, proprietary, and/or privileged information which should be treated accordingly. If you are not the intended recipient, please notify the sender immediately by return e-mail, delete this message, and destroy all physical and electronic copies. Thank you. _______________________________________________ cdi-dev mailing list cdi-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/cdi-dev Note that for all code provided on this list, the provider licenses the code under the Apache License, Version 2 (http://www.apache.org/licenses/LICENSE-2.0.html). For all other ideas provided on this list, the provider waives all patent and other intellectual property rights inherent in such information. -- Tomas Remes

I'll put in a ticket to update the spec. I agree that it was intended to be forbidden, but I couldn't find anything saying it was. John ________________________________ From: Martin Kouba <mkouba(a)redhat.com&gt; Sent: Monday, March 6, 2017 4:15 AM To: Tomas Remes; John Ament Cc: cdi-dev Subject: Re: [cdi-dev] Can an observer be both async and sync? Well, it's not 100% clear but I believe it should be forbidden. The spec only states: "An observer method may be declared by annotating a parameter @javax.enterprise.event.Observes OR @javax.enterprise.event.ObservesAsync of a default-access, public, protected or private method. That parameter is the event parameter." I think it wouldn't hurt to add: "If an event parameter is annotated with both @Observes and @ObservesAsync, the container automatically detects the problem and treats it as a definition error." Weld throws a DefinitionException. Martin Dne 6.3.2017 v 07:55 Tomas Remes napsal(a): -- Martin Kouba Senior Software Engineer Red Hat, Czech Republic ________________________________ NOTICE: This e-mail message and any attachments may contain confidential, proprietary, and/or privileged information which should be treated accordingly. If you are not the intended recipient, please notify the sender immediately by return e-mail, delete this message, and destroy all physical and electronic copies. Thank you.