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

Romain Manni-Bucau rmannibucau at gmail.com
Fri Feb 27 03:40:34 EST 2015 

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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>>>> property rights inherent in such information.
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>>
>

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