[cdi-dev] Proposal to allow any CDI managed bean in a Java EE application to listen for JMS messages
Werner Keil
werner.keil at gmail.com
Mon Aug 24 16:22:32 EDT 2015
Antoine/Nigel/all,
Sounds very interesting (especially being in both EGs)
Although the project situation ended up with a more synchronous
requirement, I did something very similar as a prototype relaying an MDB's
onMessage() to a CDI event;-)
Would be great to get something like that standardized.
Werner
On Mon, Aug 24, 2015 at 9:48 PM, <cdi-dev-request at lists.jboss.org> wrote:
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> 1. Re: JMS 2.1: Proposal to allow any CDI managed bean in a Java
> EE application to listen for JMS messages (Antoine Sabot-Durand)
> 2. Re: JMS 2.1: Proposal to allow any CDI managed bean in a Java
> EE application to listen for JMS messages (Antonio Goncalves)
> 3. Re: JMS 2.1: Proposal to allow any CDI managed bean in a Java
> EE application to listen for JMS messages (Nigel Deakin)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 24 Aug 2015 17:24:27 +0000
> From: Antoine Sabot-Durand <antoine at sabot-durand.net>
> Subject: Re: [cdi-dev] JMS 2.1: Proposal to allow any CDI managed bean
> in a Java EE application to listen for JMS messages
> To: Nigel Deakin <nigel.deakin at oracle.com>, cdi-dev at lists.jboss.org
> Message-ID:
> <CABu-YBTqjtdMxbLO=
> TcFikN9XM-zgjfDP8Chhj5bqFSy6ueKOQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Great Nigel,
>
> I'll have a look and try to give you feedback by the end of the week.
>
> Antoine
> Le lun. 24 ao?t 2015 ? 18:30, Nigel Deakin <nigel.deakin at oracle.com> a
> ?crit :
>
> > Over in the JMS 2.1 expert group I've just published some proposals to
> > allow any CDI managed bean in a Java EE
> > application to listen for JMS messages. This would be implemented as a
> > standard CDI portable extension and would become
> > a mandatory part of a full Java EE 8 application server.
> >
> > I would welcome any comments from the CDI spec experts here. If you're
> > interested in helping, please take a look at
> > https://java.net/projects/jms-spec/pages/CDIBeansAsJMSListeners
> > and send comments or questions to me or to the public
> > users at jms-spec.java.net alias.
> >
> > Thanks,
> >
> > Nigel
> > JMS 2.1 specification lead
> > _______________________________________________
> > cdi-dev mailing list
> > cdi-dev at 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.
> >
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> ------------------------------
>
> Message: 2
> Date: Mon, 24 Aug 2015 19:42:41 +0200
> From: Antonio Goncalves <antonio.goncalves at gmail.com>
> Subject: Re: [cdi-dev] JMS 2.1: Proposal to allow any CDI managed bean
> in a Java EE application to listen for JMS messages
> To: Nigel Deakin <nigel.deakin at oracle.com>
> Cc: cdi-dev <cdi-dev at lists.jboss.org>
> Message-ID:
> <CA+ZZq9_Brvtks=
> jxQ1TbtXMNm+ab3w3GZfG-2sGQYeMK2mu2jA at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Nigel, what do you mean by :
>
> "The application must obtain an instance of the JMS listener bean using
> dependency injection"
>
> In your examples, it looks like a CDI bean cannot start listening if not
> injected :
>
> @WebServlet("/myjmsservlet1")
> public class MyJMSServlet1 extends HttpServlet {
>
> *@Inject MyDepScopeListenerBean* myDepScopeListenerBean;
>
> public void service(ServletRequest req, ServletResponse res) throws
> IOException, ServletException {
> ...
> }
> }
>
>
> Did I understand well ? Is this the case ? Just like a MDB, I would like a
> CDI bean to start listening to a message without being injected, as soon as
> the application starts. Something like :
>
> *@ApplicationScoped*
> public class MyListenerBean{
>
>
>
> @JMSListener(lookup="java:global/java:global/Trades",type=JMSListener.Type.TOPIC
> )
> public void deliver(Message message) {
> ...
> }
> }
>
> Or if we manage to get the @Startup annotation to Commons Annotation :
>
> *@Startup*
> public class MyListenerBean{
>
>
>
> @JMSListener(lookup="java:global/java:global/Trades",type=JMSListener.Type.TOPIC
> )
> public void deliver(Message message) {
> ...
> }
> }
>
>
> Just thinking here
>
> Antonio
>
> On Mon, Aug 24, 2015 at 6:30 PM, Nigel Deakin <nigel.deakin at oracle.com>
> wrote:
>
> > Over in the JMS 2.1 expert group I've just published some proposals to
> > allow any CDI managed bean in a Java EE
> > application to listen for JMS messages. This would be implemented as a
> > standard CDI portable extension and would become
> > a mandatory part of a full Java EE 8 application server.
> >
> > I would welcome any comments from the CDI spec experts here. If you're
> > interested in helping, please take a look at
> > https://java.net/projects/jms-spec/pages/CDIBeansAsJMSListeners
> > and send comments or questions to me or to the public
> > users at jms-spec.java.net alias.
> >
> > Thanks,
> >
> > Nigel
> > JMS 2.1 specification lead
> > _______________________________________________
> > cdi-dev mailing list
> > cdi-dev at 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.
> >
>
>
>
> --
> Antonio Goncalves
> Software architect, Java Champion and Pluralsight author
>
> Web site <http://www.antoniogoncalves.org> | Twitter
> <http://twitter.com/agoncal> | LinkedIn <
> http://www.linkedin.com/in/agoncal> |
> Pluralsight
> <http://pluralsight.com/training/Authors/Details/antonio-goncalves> |
> Paris
> JUG <http://www.parisjug.org> | Devoxx France <http://www.devoxx.fr>
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> ------------------------------
>
> Message: 3
> Date: Mon, 24 Aug 2015 20:47:51 +0100
> From: Nigel Deakin <nigel.deakin at oracle.com>
> Subject: Re: [cdi-dev] JMS 2.1: Proposal to allow any CDI managed bean
> in a Java EE application to listen for JMS messages
> To: Antonio Goncalves <antonio.goncalves at gmail.com>
> Cc: cdi-dev <cdi-dev at lists.jboss.org>
> Message-ID: <55DB74E7.4080609 at oracle.com>
> Content-Type: text/plain; charset="utf-8"
>
> On 24/08/2015 18:42, Antonio Goncalves wrote:
> > Nigel, what do you mean by :
> >
> > "The application must obtain an instance of the JMS listener bean using
> dependency injection"
> >
> > In your examples, it looks like a CDI bean cannot start listening if not
> injected :
> >
> > @WebServlet("/myjmsservlet1")
> > public class MyJMSServlet1 extends HttpServlet {
> > *@Inject MyDepScopeListenerBean* myDepScopeListenerBean;
> > public void service(ServletRequest req, ServletResponse res) throws
> IOException, ServletException {
> > ...
> > }
> > }
> >
> >
> > Did I understand well ? Is this the case ? Just like a MDB, I would like
> a CDI bean to start listening to a message
> > without being injected, as soon as the application starts.
>
> My starting point is that these are normal CDI beans which are created
> just like any other CDI bean. The bean's
> postCreate behaviour (inserted by the extension) would connect to the JMS
> provider and start listening for messages. The
> bean's preDestroy behaviour would stop listening for messages and
> disconnect from the JMS provider.
>
> As I understand it, if you want to create a CDI managed bean (so that it
> is managed by CDI) then you have to inject it
> into some code somewhere.
>
> Additionally, if the bean is normal scoped, you have to trigger lazy
> instantiation by calling a method on the injected
> bean proxy (e.g. toString()).
>
> > Something like :
> >
> > *@ApplicationScoped*
> > public class MyListenerBean{
> >
> @JMSListener(lookup="java:global/java:global/Trades",type=JMSListener.Type.TOPIC
> )
> > public void deliver(Message message) {
> > ...
> > }
> > }
> >
>
> If I understand things correctly, if this is a normal CDI bean then this
> alone is not sufficient to cause an instance of
> the bean to be created.
>
> You also need to
> (1) inject it into some other bean
> (2) create that other bean and
> (3) call a method on the MyListenerBean to trigger lazy initialisation.
>
> I'm trying to avoid getting ahead of myself here. My current proposals
> simply apply to normal CDI managed beans created
> in the normal way (via injection and lazy initialisation). But I could
> certainly see a benefit in extending this to
> allow JMS listener beans to be created in other ways. In particular:
>
> (a) Creating the bean instance as soon as the bean into which it is
> injected enters a new scope rather than waiting for
> the application to call a method on it (so-called eager initialisation).
> That sounds relatively straightforward to me;
> this could either be a new standard CDI feature available to all
> normal-scoped beans, or something specific to beans
> annotated with @JMSListener.
>
> (b) Creating the bean instance without the need to inject it anywhere. As
> you suggest, in the case of ApplicationScoped
> beans this would make JMS listener beans more like MDBs. But it might be
> equally useful to support this for other normal
> scopes. For example, could we annotate a @RequestScoped bean so that every
> time a new request scope started, an instance
> of the bean for that scope was automatically created?
>
> > Or if we manage to get the @Startup annotation to Commons Annotation :
> >
> > *@Startup*
> > public class MyListenerBean{
> >
> @JMSListener(lookup="java:global/java:global/Trades",type=JMSListener.Type.TOPIC
> )
> > public void deliver(Message message) {
> > ...
> > }
> > }
> >
>
> That looks as if it's tied to ApplicationScoped. I'd rather look for
> something more general.
>
> Thanks for your comments so far. You're raising issues I have been
> thinking about for some time.
>
> Nigel
>
>
>
> >
> > Just thinking here
> >
> > Antonio
> >
> > On Mon, Aug 24, 2015 at 6:30 PM, Nigel Deakin <nigel.deakin at oracle.com
> <mailto:nigel.deakin at oracle.com>> wrote:
> >
> > Over in the JMS 2.1 expert group I've just published some proposals
> to allow any CDI managed bean in a Java EE
> > application to listen for JMS messages. This would be implemented as
> a standard CDI portable extension and would
> > become
> > a mandatory part of a full Java EE 8 application server.
> >
> > I would welcome any comments from the CDI spec experts here. If
> you're interested in helping, please take a look at
> > https://java.net/projects/jms-spec/pages/CDIBeansAsJMSListeners
> > and send comments or questions to me or to the public
> users at jms-spec.java.net <mailto:users at jms-spec.java.net> alias.
> >
> > Thanks,
> >
> > Nigel
> > JMS 2.1 specification lead
> > _______________________________________________
> > cdi-dev mailing list
> > cdi-dev at lists.jboss.org <mailto:cdi-dev at 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.
> >
> >
> >
> >
> > --
> > Antonio Goncalves
> > Software architect, Java Champion and Pluralsight author
> >
> > Web site <http://www.antoniogoncalves.org> | Twitter <
> http://twitter.com/agoncal> | LinkedIn
> > <http://www.linkedin.com/in/agoncal> | Pluralsight
> > <http://pluralsight.com/training/Authors/Details/antonio-goncalves> |
> Paris JUG <http://www.parisjug.org> | Devoxx
> > France <http://www.devoxx.fr>
>
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