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

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(a)redhat.com&gt; 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(a)redhat.com&gt; > 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/2c362161e18dd521f8e83c27151ddad46... >> >> Let me know your thoughts. >> >> Thanks, >> >> John >> >> >> _______________________________________________ >> 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). 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