[cdi-dev] Feedback - CDI bootstrap API (CDI-26)
Jozef Hartinger
jharting at redhat.com
Wed Mar 4 09:46:47 EST 2015
Sure, I am not saying Unmanaged should not be used at all. Under given
circumstances it makes sense to use Unmanaged. I however don't think it
fits as the general recommended way of using CDI in SE because if a
given class is a bean already, the managed instance should be obtained
instead of creating an unmanaged instance.
On 03/04/2015 02:04 PM, Romain Manni-Bucau wrote:
> Your definition seems to fit the standalone need: libraries = not CDI
> based code (case of a standalone), the runner class (Mymain) doesnt
> have to be a CDI bean but has to get injections to launch the CDI code.
>
>
> 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 13:59 GMT+01:00 Jozef Hartinger <jharting at redhat.com
> <mailto:jharting at redhat.com>>:
>
> UnmanagedInstance is provided to make it easier for libraries to
> perform dependency injection on classes that are for some reason
> not CDI beans. It should not be a substitute for lookup of CDI
> beans. Therefore, I do not see UnmanagedInstance fitting here.
>
>
> On 03/04/2015 01:47 PM, Romain Manni-Bucau wrote:
>> Hmm
>>
>> I think one of the main point I try to push is we have a bunch of
>> API to do it already, if we need yet another API to do the same
>> we have several choices:
>> - we love creating APIs
>> - all previous APIs are failures and should be deprecated or fixed
>> - there is a full mismatch with embedded and EE case (but we have
>> existing proofs it is not the case)
>>
>> I think we should help user to not be lost between all APIs and I
>> strongly believe we can't do anything on container to lookup
>> beans (EJBContainer#getContext was a try which is close to it but
>> it actually just limited user experience compared to existing
>> solutions).
>>
>> What's the issue with UnmanagedInstance?
>>
>>
>>
>> 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 13:43 GMT+01:00 Jozef Hartinger <jharting at redhat.com
>> <mailto:jharting at redhat.com>>:
>>
>> The only argument I found supporting a strict separation of
>> those two APIs is that it makes it easier to control when a
>> user should or should not use boot (i.e. it should not be
>> used in EE for example).
>>
>> That's a good argument. It's not however necessarily only
>> achieved by two separate interfaces but can be as well be
>> achieved with a subclass, e.g:
>> - CDI for runtime operations only
>> - StartedCDI extends CDI (or CDIContainer or whatever - the
>> name does not matter at this point) for runtime operations +
>> shutdown.
>>
>> Normally, CDI is available only. The boot API however would
>> return StartedCDI thus allowing a user to shutdown what they
>> started.
>>
>>
>>
>> On 03/04/2015 12:24 PM, John D. Ament wrote:
>>> This is actually based on what we discussed in one of the EG
>>> meetings
>>>
>>> http://transcripts.jboss.org/meeting/irc.freenode.org/cdi-dev/2015/cdi-dev.2015-01-14-17.04.log.html
>>>
>>> John
>>>
>>> On Wed, Mar 4, 2015 at 4:05 AM Jozef Hartinger
>>> <jharting at redhat.com <mailto:jharting at redhat.com>> wrote:
>>>
>>> Well it's nowhere given that we must have two separate
>>> interfaces for this. We can combine the start/stop API
>>> with the existing one to provide an application with a
>>> single reference representing the CDI container.
>>>
>>>
>>> On 02/28/2015 07:05 PM, John D. Ament wrote:
>>>> 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 <mailto: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 <mailto: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 <mailto: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 <mailto: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
>>>> <mailto: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
>>>> <mailto: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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>>>> <mailto:cdi-dev at lists.jboss.org>
>>>> >>>>>> https://lists.jboss.org/mailman/listinfo/cdi-dev
>>>> >>>>>>
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>>>> >>
>>>> >
>>>>
>>>
>>
>>
>
>
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