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From Jean-Baptiste Onofré ...@nanthrax.net>
Subject Re: [DISCUSSION] Karaf Boot
Date Thu, 10 Sep 2015 16:43:41 GMT
Exactly: I think it's better to discuss around a proto than just 
"concepts by e-mail". Like this we can exchange different standpoints.

That's why I gonna move forward on the proto, and especially the samples 
that will provide different use cases.


On 09/10/2015 06:40 PM, Christian Schneider wrote:
> I am fully positive on a prototype. Especially as it allows to discuss
> on a final design. Be careful though with a release as people then
> quickly start to build production code from it.
> Christian
> Am 10.09.2015 um 18:32 schrieb Jean-Baptiste Onofré:
>> I got your point.
>> The reason why I started from new abstract/high level annotations that
>> create blueprint is because the features set is interesting.
>> It's just a proto, so I would like to complete it, just to illustrate
>> how it would be easier to a developer to start with karaf-boot.
>> My only motivation: central point, easy to use to create "key turn"
>> artifacts.
>> Spring ROO approach is indeed interesting. I will try to sketch
>> something on phase 2 of the proto.
>> Regards
>> JB
>> On 09/10/2015 06:27 PM, Christian Schneider wrote:
>>> We fully agree that the current effort to set up an enterprise project
>>> is too big. We also agree that we need to cover the people that
>>> currently try out spring boot and provide something that is similarly
>>> easy to start with.
>>> So I think we need to look into how to make this easier. Rewrapping
>>> annotations is the solution of spring boot and they have their
>>> motiviation to do this. I really doubt that all of this motiviations
>>> benefits the users.
>>> So while I think it makes sense to pick some good ideas from spring boot
>>> I think we should not blindly do the same just to compete. The part of
>>> spring boot that I like is the creation of the self contained artifact.
>>> Which annotations to use depends on the framework you use. CDI/JEE is
>>> supported by the maven blueprint plugin or pax-cdi. The DS annoations
>>> are supported by SCR. It would not make sense to mix them in one bundle.
>>> So I think we need to provide tooling to create each of the three sets.
>>> Of course we can start with only one of these. I think the approach of
>>> spring roo would make a lot of sense for us. Have a shell that allows to
>>> add functionality to a project. The reason why I would choose this is
>>> that the end result is fully standards based and can then also work
>>> without the setup tooling.
>>> Christian
>>> Am 10.09.2015 um 18:15 schrieb Jean-Baptiste Onofré:
>>>> So, let me ask just a question: do you think, right now, it's easy and
>>>> quick to create a bundle ready to use with CDI annotation for instance
>>>> (dealing with the dependencies, etc) ? Moreover, you make a point:
>>>> which annotations would you chose ? CDI, SCR, JEE, ?
>>>> Think the project not as a big one, but a collection of small projects
>>>> (like in microservice).
>>>> If we don't provide tooling like karaf-boot, without knowing the
>>>> details, new developers will go to spring-boot: and it's exactly what
>>>> spring-boot does: they rewrap annotations (on a higher level),
>>>> leveraging other annotations and technologies.
>>>> Regards
>>>> JB
>>>> On 09/10/2015 06:08 PM, Christian Schneider wrote:
>>>>> I already created such a maven plugin in aries. The user can use
>>>>> standard CDI and JEE annotations and the result is blueprint xml.
>>>>> How is the new approach different / better?
>>>>> Why should it be good for the developer to move away from well defined
>>>>> standard annotations and use custom annotations that bind him to
>>>>> karaf?
>>>>> I mean if this is created by the spring guys I know they want to catch
>>>>> people by perceived simplicity and then make sure to make it difficult
>>>>> to switch. As an open source comminity I do not know why we should do
>>>>> something like this.
>>>>> Abstracting away from frameworks just means you create another layer
>>>>> that people then also have to learn. There were some cases in the past
>>>>> where this make sense because the underlying frameworks sucked
>>>>> (like JEE
>>>>> 2). This is not the case today though I think.
>>>>> What kind of use case do you have in mind? Every project starts small
>>>>> but it needs to be able to grow then. You can not start with custom
>>>>> annoations and then tell people to later switch to something else
>>>>> when the
>>>>> project grows. I think it makes more sense to make it easier for
>>>>> people
>>>>> to use the standard annoations and use the right dependencies.
>>>>> If we simply provide a tooling that makes it easy to start with SCR or
>>>>> blueprint we provide much more value for people as thery can then grow
>>>>> without any breaking changes.
>>>>> Christian
>>>>> Am 10.09.2015 um 17:46 schrieb Jean-Baptiste Onofré:
>>>>>> Because all these annotations are runtime: here we talk about tooling
>>>>>> at build time.
>>>>>> More over, the purpose is to provide more high level annotations,
>>>>>> which abstract actual annotations/frameworks that we can use under
>>>>>> hood.
>>>>>> The purpose of centralizing all in karaf-boot is to have a central
>>>>>> project: the developer just use karaf-boot, it doesn't really know
>>>>>> what technologies are involved behind the scene.
>>>>>> For instance, in spring-boot, they use activemq, jersey, etc, but
>>>>>> from spring-boot. The developers don't know a rest service use jersey
>>>>>> for instance, it's completely abstracted.
>>>>>> Again the purpose is to simplify life for developers: splitting the
>>>>>> annotations in different projects introduces complexity (at least
>>>>>> find the dependencies and core import packages).
>>>>>> If an advanced developer wants to use CDI, SCR, etc, he can of
>>>>>> course.
>>>>>> Regards
>>>>>> JB
>>>>>> On 09/10/2015 05:40 PM, Christian Schneider wrote:
>>>>>>> I am not really enthusiastic about duplicating functionality
>>>>>>> cxf or
>>>>>>> aries. Aries supports a very nice approach for injections, jpa
>>>>>>> jta.
>>>>>>> Why should it make sense to recreate that?
>>>>>>> Aries blueprint also has annoation support even in two flavors
>>>>>>> custom). How does the new approach interact with this?
>>>>>>> Instead I propose we create support for such annotations in the
>>>>>>> respective projects (where they are missing) and concentrate
>>>>>>> karaf as
>>>>>>> a container not an application development framework.
>>>>>>> By leveraging the existing frameworks we profit from their own
>>>>>>> development teams. Whatever we recreate will have to be developed
>>>>>>> by the
>>>>>>> very few resources of the karaf team.
>>>>>>> Christian
>>>>>>> Am 10.09.2015 um 16:53 schrieb Jean-Baptiste Onofré:
>>>>>>>> Hi Guillaume,
>>>>>>>> thanks for your feedback.
>>>>>>>> I fully agree about providing more high level annotations
>>>>>>>> what I
>>>>>>>> do with @jpa, @rest, @soap, @jta annotations).
>>>>>>>> I agree that the current annotations are too low level, and
>>>>>>>> blueprint
>>>>>>>> "oriented". I just move forward a bit with the current codebase,
>>>>>>>> just
>>>>>>>> to illustrate karaf-boot usage in the samples.
>>>>>>>> But again, you are right, and I will create a new annotations
>>>>>>>> One of the purpose of karaf-boot annotations is to "abstract"
>>>>>>>> actual code/artifact that we generate. So, if now we generate
>>>>>>>> blueprint, without changing the karaf-boot annotations, we
will be
>>>>>>>> able to generate something else (why not SCR, etc).
>>>>>>>> I agree with a BOM, but I think it's interesting to provide
>>>>>>>> - providing a ready to use parent pom allows developers to
create a
>>>>>>>> very simple pom.xml where all plugins and dependencies are
>>>>>>>> defined
>>>>>>>> - for more advanced devs, they can create their own pom.xml
>>>>>>>> starting
>>>>>>>> from the BOM or archetype.
>>>>>>>> Thanks again for your feedback !
>>>>>>>> Regards
>>>>>>>> JB
>>>>>>>> On 09/10/2015 04:44 PM, Guillaume Nodet wrote:
>>>>>>>>> I like the idea.
>>>>>>>>> For the annotations, we need to keep really high level.
>>>>>>>>> annotations in
>>>>>>>>> the code base right now are much too close to blueprint.
>>>>>>>>> I think we need to grab a small enough subset so that
>>>>>>>>> annotations
>>>>>>>>> are
>>>>>>>>> easy to understand for beginners and without any ambiguities,
>>>>>>>>> even at
>>>>>>>>> the
>>>>>>>>> cost of features.
>>>>>>>>> For example, I think we should restrict to constructor
>>>>>>>>> injection, so
>>>>>>>>> that
>>>>>>>>> we don't have any bind / rebind / init methods.  We simply
need an
>>>>>>>>> optional
>>>>>>>>> @Destroy.  In case the dependencies change at runtime,
>>>>>>>>> destroy
>>>>>>>>> the
>>>>>>>>> bean / service and recreate it the dependencies are still
>>>>>>>>> after
>>>>>>>>> the
>>>>>>>>> change.
>>>>>>>>> If blueprint is to be hidden completely, we may find
a better
>>>>>>>>> alternative
>>>>>>>>> in SCR or even Felix Dependency Manager, but it does
not matter
>>>>>>>>> too
>>>>>>>>> much
>>>>>>>>> for now.
>>>>>>>>> I agree with the idea of using a BOM instead of a parent
>>>>>>>>> possible.  I'm
>>>>>>>>> not very familiar, but this is less invasive.
>>>>>>>>> The real problems will come with the support of higher
>>>>>>>>> annotations
>>>>>>>>> for JAXRS, JPA, etc...
>>>>>>>>> Not really sure how to handle those yet...
>>>>>>>>> 2015-09-09 16:32 GMT+02:00 Jean-Baptiste Onofré <jb@nanthrax.net>:
>>>>>>>>>> Hi all,
>>>>>>>>>> I worked on a prototype about Karaf Boot.
>>>>>>>>>> Let me give you some backgrounds and discuss about
that all
>>>>>>>>>> together.
>>>>>>>>>>   Why Karaf Boot ?
>>>>>>>>>>   ----------------
>>>>>>>>>> When you develop artifacts (bundles) to be deployed
in Karaf, you
>>>>>>>>>> can see
>>>>>>>>>> that the actual time that you spend on your business
code is
>>>>>>>>>> finally
>>>>>>>>>> largely less important that all the plumbing effort
that you have
>>>>>>>>>> to do
>>>>>>>>>> (writing OSGi Activator, or blueprint/scr descriptor,
>>>>>>>>>> It means that your "go to market" is longer, and
we should
>>>>>>>>>> provide
>>>>>>>>>> something that allows you to focus on your code.
>>>>>>>>>> Even if SCR annotations is a very good step forward,
some use
>>>>>>>>>> cases are
>>>>>>>>>> not so easy to do (JPA, JTA for instance).
>>>>>>>>>> And anyway, you have to prepare your pom.xml with
>>>>>>>>>> plugin
>>>>>>>>>> and
>>>>>>>>>> dependency.
>>>>>>>>>> Moreover, when you have your artifacts, you have
to prepare Karaf
>>>>>>>>>> container, and deploy those artifacts there. Even
if it's
>>>>>>>>>> "container"
>>>>>>>>>> approach is the most important for me, we can give
even more
>>>>>>>>>> flexibility by
>>>>>>>>>> providing a way to embed and prepare Karaf in a ready
to execute
>>>>>>>>>> jar/artifact.
>>>>>>>>>>   What is Karaf Boot ?
>>>>>>>>>>   --------------------
>>>>>>>>>> Karaf Boot provides four components:
>>>>>>>>>> * karaf-boot-parent is the Maven parent pom that
your project
>>>>>>>>>> just
>>>>>>>>>> inherit: that's all ! All plugins, dependencies,
etc are
>>>>>>>>>> described
>>>>>>>>>> in this
>>>>>>>>>> parent, you even don't have to define packaging as
>>>>>>>>>> standard
>>>>>>>>>> jar is
>>>>>>>>>> fine.
>>>>>>>>>> * karaf-boot (coming with karaf-boot-parent) provides
>>>>>>>>>> that you
>>>>>>>>>> use directly in your business code (like @Bean, @Service,
>>>>>>>>>> @Reference,
>>>>>>>>>> @Inject, etc): again, your focus on your code, karaf-boot
>>>>>>>>>> with
>>>>>>>>>> the
>>>>>>>>>> plumbing.
>>>>>>>>>> * karaf-boot-maven-plugin (coming with karaf-boot-parent)
>>>>>>>>>> the
>>>>>>>>>> classes
>>>>>>>>>> and generate a blueprint XML. For now, I'm using
>>>>>>>>>> generation
>>>>>>>>>> (because we can cover lot of use cases, for instance,
I plan to
>>>>>>>>>> provide
>>>>>>>>>> @rest annotation that will generate blueprint XML
with cxf jaxrs
>>>>>>>>>> server,
>>>>>>>>>> etc).
>>>>>>>>>> * karaf-boot-starter is the module providing a convenient
way to
>>>>>>>>>> embed,
>>>>>>>>>> configure and bootstrap Karaf.
>>>>>>>>>> Just to illustrate this, let's take a look on the
>>>>>>>>>> karaf-boot-sample-simple.
>>>>>>>>>> The pom.xml is really simple:
>>>>>>>>>> <?xml version="1.0" encoding="UTF-8"?>
>>>>>>>>>> <project xmlns="http://maven.apache.org/POM/4.0.0"
>>>>>>>>>> http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="
>>>>>>>>>> http://maven.apache.org/POM/4.0.0
>>>>>>>>>> http://maven.apache.org/xsd/maven-4.0.0.xsd">
>>>>>>>>>> <modelVersion>4.0.0</modelVersion>
>>>>>>>>>>      <parent>
>>>>>>>>>> <groupId>org.apache.karaf.boot</groupId>
>>>>>>>>>> <artifactId>karaf-boot-parent</artifactId>
>>>>>>>>>> <version>1.0.0-SNAPSHOT</version>
>>>>>>>>>>      </parent>
>>>>>>>>>> <artifactId>karaf-boot-sample-simple</artifactId>
>>>>>>>>>>      <version>1.0.0-SNAPSHOT</version>
>>>>>>>>>> </project>
>>>>>>>>>> You can see, the only thing that the developer has
to do: define
>>>>>>>>>> karaf-boot-parent as parent pom. That's all.
>>>>>>>>>> Now, in the code, you have just one bean that we
want to run:
>>>>>>>>>> package org.apache.karaf.boot.sample.simple;
>>>>>>>>>> import org.apache.karaf.boot.Bean;
>>>>>>>>>> import org.apache.karaf.boot.Init;
>>>>>>>>>> @Bean(id = "simple-bean")
>>>>>>>>>> public class SimpleBean {
>>>>>>>>>>      @Init
>>>>>>>>>>      public void simple() {
>>>>>>>>>>          System.out.println("Hello world");
>>>>>>>>>>      }
>>>>>>>>>> }
>>>>>>>>>> You can see the @Bean and @Init karaf-boot annotations.
>>>>>>>>>> karaf-boot-maven-plugin will generate the blueprint
>>>>>>>>>> using
>>>>>>>>>> this.
>>>>>>>>>>   Current Status
>>>>>>>>>>   --------------
>>>>>>>>>> I pushed Karaf Boot structure there:
>>>>>>>>>> https://github.com/jbonofre/karaf-boot
>>>>>>>>>> It's a mix of rewrapping of existing code (from aries,
>>>>>>>>>> etc) and
>>>>>>>>>> additions.
>>>>>>>>>> I created the annotations, I'm now working on the
>>>>>>>>>> karaf-boot-maven-plugin
>>>>>>>>>> based on Christian's work in aries (I'm actually
scanning the
>>>>>>>>>> boot
>>>>>>>>>> annotations now, and generating the XML).
>>>>>>>>>> I will push new changes later today and tomorrow.
>>>>>>>>>>   Open Questions
>>>>>>>>>>   ---------------
>>>>>>>>>> * For now, I would prefer to be 'artifacts' and 'resources'
>>>>>>>>>> generator: I
>>>>>>>>>> think it's better than to depend to a feature running
>>>>>>>>>> Karaf, but
>>>>>>>>>> it's
>>>>>>>>>> open to discussion.
>>>>>>>>>> * I'm now generating blueprint. Probably native OSGi
or scr
>>>>>>>>>> generation can
>>>>>>>>>> make sense.
>>>>>>>>>> * I'm generating bundles: thanks to the Karaf4 features
>>>>>>>>>> resolver, as
>>>>>>>>>> the
>>>>>>>>>> bundles provide requirements/capabilities metadata,
I think
>>>>>>>>>> it's a
>>>>>>>>>> good
>>>>>>>>>> start. However, maybe it's worth to be able to create
>>>>>>>>>> kar,
>>>>>>>>>> profile.
>>>>>>>>>> Thoughts ?
>>>>>>>>>> Thanks,
>>>>>>>>>> Regards
>>>>>>>>>> JB
>>>>>>>>>> --
>>>>>>>>>> Jean-Baptiste Onofré
>>>>>>>>>> jbonofre@apache.org
>>>>>>>>>> http://blog.nanthrax.net
>>>>>>>>>> Talend - http://www.talend.com

Jean-Baptiste Onofré
Talend - http://www.talend.com

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