[cdi-dev] Feedback - CDI bootstrap API (CDI-26)

Wed Mar 4 04:52:26 EST 2015

@Antoine: to boot multiple BM it would need to break contextuality of CDI,
one way being to forbid any serialization (not a big constraint in SE). In
this case container is bound to a bean manager which changes the API Jozef
propose

Romain Manni-Bucau
@rmannibucau <https://twitter.com/rmannibucau> |  Blog
<http://rmannibucau.wordpress.com> | Github <https://github.com/rmannibucau> |
LinkedIn <https://www.linkedin.com/in/rmannibucau> | Tomitriber
<http://www.tomitribe.com>

2015-03-04 10:49 GMT+01:00 Antoine Sabot-Durand <antoine at sabot-durand.net>:

> Hi John,
>
> I think it could be a good idea to write down all of these to have a more
> stable doc for discussion. You should update the google doc with the result
> of this discussion.
>
> I agree with the following points in this thread :
>
> - Minimize the number of new Class / Interface. CDI and CDIProvider usage
> is still not very clear for end user so we should add the strict minimum
> and try to enhance existing API / SPI when possible
> - Be able to bootstrap CDI without returning BeanManager (env if the API
> give possibility to access it if needed). End user don’t need that : CDI
> app can start with an observer for instance
>
> Something not dealt with but that we should keep in mind :
> - Providing a Java SE solution that could be easily used for a servlet
> bootstrap of CDI. I don’t know if we’ll standardize this but we definitely
> should keep this use case in mind
>
> and my bonus, it’s out of scope but I didn’t see anytime there that
> prevent this nice to have:
> - support the possibility to boot multiple BeanManager in Java SE.
>
> Antoine
>
>
> Le 1 mars 2015 à 15:13, John D. Ament <john.d.ament at gmail.com> a écrit :
>
> So, I think I've gathered enough feedback at this point, and seen some of
> the API changes.  I'll hopefully be including some doc changes this week,
> but one question - do we want to start the SE specific stuff as its own
> asciidoc file?
>
> Changes made:
>
> - Changed return value to CDI<Object> to provide better capability out of
> the box.
> - Added AutoCloseable to CDIContainer, provided default implementation of
> calling shutdown.
> - Added synchronization support to the method body that retrieves the
> singleton instance (BTW, I'm not sure if this is even useful TBH as each
> impl, including the RI, needs to provide this class in its own format).
> - Made the params map typed to <String,Object>
>
> @Romain Your case isn't really supportable yet, until we have static
> injection support.  You'd still have to have a managed version of Runner to
> work against.
>
> John
>
> On Sat, Feb 28, 2015 at 4:11 PM Romain Manni-Bucau <rmannibucau at gmail.com>
> wrote:
>
>> Yes but not the way to get an instance. Even Unmanaged does it.
>>
>> What can be awesome is to have static inject for it:
>>
>> public class Runner {
>>
>> @Inject
>> private static MyMain main;
>>
>> public static void main(String[] arg) {
>>     try (CDIContainer c = CDIContainer.newContainer()) {
>>         main.doWork();
>>     }
>> }
>>
>> }
>>
>> And not a single additional line :).
>>  Le 28 févr. 2015 19:05, "John D. Ament" <john.d.ament at gmail.com> a
>> écrit :
>>
>> Maybe I'm misreading, but I don't see us adding another API to do the
>>> same thing here - we're introducing new functionality.
>>>
>>> CDIContainer/Loader on startup/shutdown of the application
>>>
>>> CDI for runtime usage within the application to interact with the
>>> container.
>>>
>>> John
>>>
>>> On Fri, Feb 27, 2015 at 3:40 AM Romain Manni-Bucau <
>>> rmannibucau at gmail.com> wrote:
>>>
>>>> sure I fully agree excepted I think introducing yet another API to do
>>>> the same thing is not good so super tempting to skip it and wait for
>>>> feedbacks rather than introducing it eagerly.
>>>>
>>>>
>>>> Romain Manni-Bucau
>>>> @rmannibucau
>>>> http://www.tomitribe.com
>>>> http://rmannibucau.wordpress.com
>>>> https://github.com/rmannibucau
>>>>
>>>>
>>>> 2015-02-27 8:05 GMT+01:00 Jozef Hartinger <jharting at redhat.com>:
>>>> > My point is that from the application perspective, the user obtains
>>>> one
>>>> > container handle for eventual shutdown (CDIContainer) and then looks
>>>> up a
>>>> > different container handle (CDI) that they can use for real work
>>>> (lookup /
>>>> > event dispatch / etc.) It would be cleaner if the container gave away
>>>> a
>>>> > single handle that can do all of that.
>>>> >
>>>> >
>>>> > On 02/26/2015 05:42 PM, Romain Manni-Bucau wrote:
>>>> >
>>>> > Not sure I get how a CDI instance can help.
>>>> >
>>>> > But container.getBeanManager() sounds nice is not a shortcut for
>>>> > CDI.current().getBm() otherwise it looks like duplication to me.
>>>> >
>>>> > Can we make container not contextual - dont think so? If so it makes
>>>> sense
>>>> > otherwise I fear it doesnt add much.
>>>> >
>>>> > Le 26 févr. 2015 16:19, "Jozef Hartinger" <jharting at redhat.com> a
>>>> écrit :
>>>> >>
>>>> >> I like the initialize + close() combination and the
>>>> try-with-resources
>>>> >> usage.
>>>> >> What looks weird to me is that at line one you obtain a container
>>>> handle:
>>>> >>
>>>> >> try (CDIContainer container = CDIContainer.newCDIContai...
>>>> >> CDI.current().getBeanManager() ...
>>>> >>
>>>> >> and then at line two you call a static method to perform a container
>>>> >> lookup :-/
>>>> >>
>>>> >> An API that allows you to use the container handle you already got
>>>> is way
>>>> >> better IMO, e.g.:
>>>> >>
>>>> >> try (CDIContainer container = CDIContainer.newCDIContai...
>>>> >> container.getBeanManager()
>>>> >>
>>>> >> If CDIContainer.newCDIContainer() returns an CDI instance or its
>>>> subclass,
>>>> >> we get this easily.
>>>> >>
>>>> >> On 02/26/2015 08:58 AM, Romain Manni-Bucau wrote:
>>>> >>>
>>>> >>> Hi guys
>>>> >>>
>>>> >>> why note keeping it simple?
>>>> >>>
>>>> >>> try (CDIContainer container = CDIContainer.newCDIContainer(/*
>>>> optional
>>>> >>> map to configure vendor features */)) {
>>>> >>>       CDI.current().getBeanManager()....
>>>> >>> }
>>>> >>>
>>>> >>> Not sure the point having initialize() + having shutdown = close
>>>> >>> really makes the API more fluent and modern IMO.
>>>> >>>
>>>> >>> Also to be fully SE I guess provider() method would be needed even
>>>> if
>>>> >>> optional (SPI usage by default):
>>>> >>>
>>>> >>> try (CDIContainer container =
>>>> >>>
>>>> >>> CDIContainer.provider("org.jboss.weld.WeldCdiContainerProvider").
>>>> newCDIContainer())
>>>> >>> {
>>>> >>>       CDI.current().getBeanManager()....
>>>> >>> }
>>>> >>>
>>>> >>> Finally I think having a kind of getInstance shortcut could be a
>>>> plus for
>>>> >>> SE:
>>>> >>>
>>>> >>> try (CDIContainer container = CDIContainer.newCDIContainer()) {
>>>> >>>       container.newInstance(MyAppRunner.class /* optional
>>>> qualifiers */
>>>> >>> ).run(args);
>>>> >>> }
>>>> >>>
>>>> >>> Using container to get an instance would create the instance and
>>>> bind
>>>> >>> it to the container lifecycle (mainly for predestroy) avoiding this
>>>> >>> boilerplate code in all main which will surely only be used to
>>>> launch
>>>> >>> a soft.
>>>> >>>
>>>> >>> wdyt?
>>>> >>>
>>>> >>>
>>>> >>>
>>>> >>> Romain Manni-Bucau
>>>> >>> @rmannibucau
>>>> >>> http://www.tomitribe.com
>>>> >>> http://rmannibucau.wordpress.com
>>>> >>> https://github.com/rmannibucau
>>>> >>>
>>>> >>>
>>>> >>> 2015-02-26 8:32 GMT+01:00 Jozef Hartinger <jharting at redhat.com>:
>>>> >>>>
>>>> >>>> Comments inline
>>>> >>>>
>>>> >>>> On 02/25/2015 05:53 PM, John D. Ament wrote:
>>>> >>>>
>>>> >>>> Sorry Jozef, your email fell into the pits of google inbox's "smart
>>>> >>>> sorting"
>>>> >>>> features.
>>>> >>>>
>>>> >>>> On Thu, Feb 12, 2015 at 3:18 AM Jozef Hartinger <
>>>> jharting at redhat.com>
>>>> >>>> wrote:
>>>> >>>>>
>>>> >>>>> Hi John, comments inline:
>>>> >>>>>
>>>> >>>>>
>>>> >>>>> On 02/11/2015 06:02 PM, John D. Ament wrote:
>>>> >>>>>
>>>> >>>>> Jozef,
>>>> >>>>>
>>>> >>>>> Most of what you see there is taken from the original doc, since
>>>> >>>>> everyone
>>>> >>>>> seemed to be in agreement.  I think the map is just a safeguard
>>>> in case
>>>> >>>>> of
>>>> >>>>> additional boot options available in some implementations (e.g. I
>>>> think
>>>> >>>>> OWB/OpenEJB have some options.. currently OpenEJB supports an
>>>> embedded
>>>> >>>>> CDI
>>>> >>>>> boot mode).
>>>> >>>>>
>>>> >>>>> No, I am fine with the map. What I am questioning is the type of
>>>> the
>>>> >>>>> map.
>>>> >>>>> Usually, data structures with a similar purpose use Strings as
>>>> their
>>>> >>>>> keys.
>>>> >>>>> This applies to ServletContext attributes, InvocationContext data,
>>>> >>>>> Servlet
>>>> >>>>> request/session attributes and others. I am therefore wondering
>>>> whether
>>>> >>>>> there is a usecase for the proposed unbound key signature or not.
>>>> >>>>
>>>> >>>>
>>>> >>>> I think that's more of a placeholder, I was assuming it would be
>>>> >>>> Map<String,Object> once we clarify everything.
>>>> >>>>
>>>> >>>>>
>>>> >>>>>
>>>> >>>>> We spoke a few times about BeanManager vs CDI.  BeanManager was
>>>> >>>>> preferable
>>>> >>>>> since there's no easy way to get the the instance, CDI is easier
>>>> to get
>>>> >>>>> and
>>>> >>>>> more aligned with how you would get it.  Usually people expect the
>>>> >>>>> BeanManager to be injected or available via JNDI, neither would
>>>> be the
>>>> >>>>> case
>>>> >>>>> here.
>>>> >>>>>
>>>> >>>>> If CDI 2.0 targets Java SE then this container initialization API
>>>> will
>>>> >>>>> become something that ordinary application developers use to
>>>> start/stop
>>>> >>>>> CDI
>>>> >>>>> in their applications. It therefore cannot be considered an SPI
>>>> but
>>>> >>>>> instead
>>>> >>>>> should be something easy to use. On the other hand, BeanManager is
>>>> >>>>> definitely an SPI. It is used in extension, frameworks and
>>>> generally
>>>> >>>>> for
>>>> >>>>> integration. Not much by applications directly. Therefore, I
>>>> don't see
>>>> >>>>> how
>>>> >>>>> the container bootstrap API and BeanManager fit together. IMO the
>>>> >>>>> bootstrap
>>>> >>>>> API should expose something that makes common tasks (obtaining a
>>>> >>>>> contextual
>>>> >>>>> reference and firing and event) easy, which the CDI class does.
>>>> >>>>>
>>>> >>>>> Plus do not forget that BeanManager can be obtained easily using
>>>> >>>>> CDI.getBeanManager().
>>>> >>>>
>>>> >>>>
>>>> >>>> I'm not disagreeing.  There's a few things I'd consider:
>>>> >>>>
>>>> >>>> - Is this mostly for new apps or existing?  If existing, it's
>>>> probably
>>>> >>>> using
>>>> >>>> some internal API, if new it can use whatever API we give.
>>>> >>>> - I don't want to return void, we should give some kind of
>>>> reference
>>>> >>>> into
>>>> >>>> the container when we're done booting.
>>>> >>>>
>>>> >>>> Agreed, we should not be returning void.
>>>> >>>>
>>>> >>>> - CDI is a one step retrievable reference, where as BeanManager is
>>>> a two
>>>> >>>> step reference.  With that said, BeanManager makes more sense to
>>>> return
>>>> >>>> here.  Another thought could be we invent some new class that has
>>>> both,
>>>> >>>> but
>>>> >>>> that's really redundant.
>>>> >>>>
>>>> >>>> Why do you think BeanManager makes more sense here? Especially
>>>> given the
>>>> >>>> assumption that application code is going to call this
>>>> init/shutdown
>>>> >>>> API, I
>>>> >>>> don't see BeanManager as making more sense.
>>>> >>>>
>>>> >>>>
>>>> >>>>>
>>>> >>>>>
>>>> >>>>> Yes, this is the container start API.  Sounds like you have some
>>>> good
>>>> >>>>> ideas for things like XML configuration or programmatic
>>>> configuration,
>>>> >>>>> both
>>>> >>>>> of which are being tracked under separate tickets.  One idea
>>>> might be
>>>> >>>>> for an
>>>> >>>>> optional param in the map to control packages to scan/ignore, in
>>>> that
>>>> >>>>> map.
>>>> >>>>>
>>>> >>>>> I am wondering whether this configuration should be something
>>>> optional
>>>> >>>>> built on top of the bootstrap API or whether we should consider
>>>> making
>>>> >>>>> it
>>>> >>>>> mandatory. Either way, we cannot add the bootstrap API to the spec
>>>> >>>>> without
>>>> >>>>> explicitly defining how it behaves. My implicit assumption of the
>>>> >>>>> proposal
>>>> >>>>> is that the container is supposed to scan the entire classpath for
>>>> >>>>> explicit
>>>> >>>>> or implicit bean archives (including e.g. rt.jar), discover
>>>> beans, fire
>>>> >>>>> extensions, etc. This worries me as this default behavior is far
>>>> from
>>>> >>>>> being
>>>> >>>>> lightweight, which CDI for Java SE initially aimed to be.
>>>> >>>>
>>>> >>>>
>>>> >>>> Yes, the spec must be updated to reflect the behavior of SE mode.
>>>> I
>>>> >>>> plan to
>>>> >>>> get that completely into the google doc before opening any spec
>>>> changes
>>>> >>>> in a
>>>> >>>> PR.
>>>> >>>>
>>>> >>>>>
>>>> >>>>>
>>>> >>>>> We didn't want to over load the CDI interface.  It already does a
>>>> lot.
>>>> >>>>> This is really SPI code, CDI even though it's in the spi package
>>>> is
>>>> >>>>> used in
>>>> >>>>> a lot of application code.
>>>> >>>>>
>>>> >>>>> I would personally prefer to have it all in one place. Having
>>>> >>>>> CDIContainer, CDIContainerLoader, CDI and CDIProvider makes it
>>>> more
>>>> >>>>> difficult to know when to use what.
>>>> >>>>
>>>> >>>>
>>>> >>>> The problem is that most CDI (the interface) operations are
>>>> against a
>>>> >>>> running container.  I think we spoke about leveraging CDIProvider
>>>> at one
>>>> >>>> point (in fact, I mistakenly called CDIContainer CDIProvider not
>>>> even
>>>> >>>> realizing it was there).  I doubt that most app developers use it
>>>> >>>> currently,
>>>> >>>> there's not even a way to get a reference to it that I'm aware
>>>> of.  It's
>>>> >>>> used by the implementor only.
>>>> >>>>
>>>> >>>> I don't think there's a conflict. CDI class would still only
>>>> provide
>>>> >>>> methods
>>>> >>>> to be run against a running container. The difference is that there
>>>> >>>> would be
>>>> >>>> additional static methods to get this running container (CDI
>>>> class) to
>>>> >>>> you
>>>> >>>> by starting the container.
>>>> >>>>
>>>> >>>> Either way, I agree that reusing CDIProvider is a must. There is no
>>>> >>>> reason
>>>> >>>> to define a new class for the same purpose.
>>>> >>>>
>>>> >>>>
>>>> >>>> I expect that my changes in the CDI spec around this will state,
>>>> along
>>>> >>>> the
>>>> >>>> lines of:
>>>> >>>>
>>>> >>>> To retrieve a CDIContainer to launch, do this:
>>>> >>>>
>>>> >>>> CDIContainer container = CDIContainerLocator.getCDIContainer();
>>>> >>>> container.initialize();
>>>> >>>> ... do work
>>>> >>>>
>>>> >>>> Once you want to shutdown the container, do this:
>>>> >>>>
>>>> >>>> container.shutdown();
>>>> >>>>
>>>> >>>> (we may want to consider implementing AutoCloseable, an oversight
>>>> on my
>>>> >>>> part)
>>>> >>>>
>>>> >>>> and then later on
>>>> >>>>
>>>> >>>> - What happens if I call CDIContainerLocator in an app server
>>>> >>>>
>>>> >>>> - It throws an IllegalStateException.
>>>> >>>>
>>>> >>>> - The container provides no beans of type CDIContainer, it is
>>>> managed
>>>> >>>> outside of the CDI container.
>>>> >>>>
>>>> >>>>
>>>> >>>>>
>>>> >>>>>
>>>> >>>>> John
>>>> >>>>>
>>>> >>>>> On Wed Feb 11 2015 at 4:21:50 AM Jozef Hartinger <
>>>> jharting at redhat.com>
>>>> >>>>> wrote:
>>>> >>>>>>
>>>> >>>>>> Hi John, some thoughts:
>>>> >>>>>>
>>>> >>>>>> - instead of using BeanManager it makes more sense to me to
>>>> return a
>>>> >>>>>> CDI
>>>> >>>>>> instance, which is a more user-friendly API (and it also exposes
>>>> >>>>>> access to
>>>> >>>>>> BeanManager)
>>>> >>>>>> - is there a usecase for arbitrary keys of the "params" map or is
>>>> >>>>>> Map<String, ?> sufficient?
>>>> >>>>>> - if we could move the shutdown() method from CDIContainer to the
>>>> >>>>>> actual
>>>> >>>>>> container handle that we obtain from initialize(), that would
>>>> look
>>>> >>>>>> more
>>>> >>>>>> object-oriented
>>>> >>>>>> - what exactly is initialize() supposed to do? Is it supposed to
>>>> start
>>>> >>>>>> scanning the entire classpath for CDI beans? That could be a
>>>> problem
>>>> >>>>>> especially with spring-boot-like fat jars. I think we need an
>>>> API to
>>>> >>>>>> tell
>>>> >>>>>> the container which classes / packages to consider. Something
>>>> like
>>>> >>>>>> Guice's
>>>> >>>>>> binding API perhaps?
>>>> >>>>>>
>>>> >>>>>> - the proposal makes me wonder whether retrofitting this
>>>> functionality
>>>> >>>>>> to
>>>> >>>>>> the CDI class wouldn't be a better option. It could look like:
>>>> >>>>>>
>>>> >>>>>> CDI container = CDI.initialize();
>>>> >>>>>> container.select(Foo.class).get();
>>>> >>>>>> container.shutdown();
>>>> >>>>>>
>>>> >>>>>> compare it to:
>>>> >>>>>>
>>>> >>>>>> CDIContainer container = CDIContainerLoader. getCDIContainer();
>>>> >>>>>> BeanManager manager = container.initialize();
>>>> >>>>>> manager.getBeans(...);
>>>> >>>>>> container.shutdown(manager);
>>>> >>>>>>
>>>> >>>>>>
>>>> >>>>>> On 02/10/2015 06:58 PM, John D. Ament wrote:
>>>> >>>>>>
>>>> >>>>>> All,
>>>> >>>>>>
>>>> >>>>>> I have the updated API here, and wanted to solicit any final
>>>> feedback
>>>> >>>>>> before updating the google doc and spec pages.
>>>> >>>>>>
>>>> >>>>>>
>>>> >>>>>>
>>>> >>>>>> https://github.com/johnament/cdi/commit/
>>>> 2c362161e18dd521f8e83c27151ddad467a1c01c
>>>> >>>>>>
>>>> >>>>>> Let me know your thoughts.
>>>> >>>>>>
>>>> >>>>>> Thanks,
>>>> >>>>>>
>>>> >>>>>> John
>>>> >>>>>>
>>>> >>>>>>
>>>> >>>>>> _______________________________________________
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>>>> >>>>>>
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>>>> >>
>>>> >
>>>>
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