On 9/10/2015 2:58 PM, Achim Nierbeck wrote:
<stuff deleted>
The microservice dance
actually it's just add a rest-service on top of a OSGi service, that's all
that is needed in Karaf.
Right now I'm not in favor of any certain framework. CXF seems a bit
bloated but is known to work, but requires blueprint.
Jersey, I've seen that to be working with "plain" OSGi. A bit of polishing
and it should be quite easy to use, especially with CDI at hand.
I would suggest the use of OSGi Remote Services/RSA [1]. The Remote
Services spec defines standard service properties triggering the export
of the service via some unspecified distribution
system/transport...typically in response to service registration done
through whatever means...e.g. DS, java code, Dependency Manager, Spring,
or anything else that uses the service registry. One of the standardized
properties allows a distribution provider to be selected, separately for
each service instance if needed.
Each distribution provider can be as small or large as required for the
use case. For example, ECF's RSA impl now supports using CXF, Jersey,
or other Jax-RS implementations along with Hazelcast, rosgi, tcp, JMS,
MQTT, and other providers [2]. Or if you need to you can create and
use your own distribution provider. In any case, the service won't be
bound to any distribution provider or RSA impl on server or clients, and
can be changed prior to service registration.
Scott
[1] http://www.osgi.org/Specifications/HomePage
[2]
https://wiki.eclipse.org/Tutorial:_Using_REST_and_OSGi_Standards_for_Micro_Services
https://wiki.eclipse.org/Tutorial:_Exposing_a_Jax_REST_service_as_an_OSGi_Remote_Service
But it needs more to dance the microservice dance, you need "small"
containers ... which is quite contrary to the way Karaf and OSGi in general
is working with services.
But this is the point I think the karaf profiles come in handy. You don't
need a full blown Karaf, just a basic infrastructure with your own Bundle,
might as well ignore the shell. In the end dump that into a docker
container and if you need to do a bugfix do it the "docker" - way.
spring-boot brings it all in one go
karaf-boot should do the same, but actually I fear we do more then needed.
For a new Project setup I'd rather would like to see different
karaf-starter-* BOMs and a karaf:run maven plugin
Some more docuementation for the profiles of Karaf could also be helpful :D
to build minimalistic karaf instances runnable in docker containers.
Regarding the karaf:run it might be interesting to "re-activate" the
pax:run maven plugin to run nicely with a karaf instance, or use it as
foundation for the karaf:run maven plugin.
So in the end, do we really need all this?
I'm not so sure, but we surely need an easier "to use" approach.
Therefore we should first focus on having easier setup of bundle
development.
-> karaf-boot-starter-* BOMs should take care of that
-> karaf:run should make it easier to have a running container
Do we need new annotations? I can't see that yet.
Instead we should/could focus on the following:
a) make sure DS also is capable to work with JPA/JTA and some other
enterprise annotations
b) make sure CDI works with runtime JPA/JTA annotation smoothly
c) provide more demos and archetypes with OSGi and CDI annotations
regards, Achim
2015-09-10 20:41 GMT+02:00 Jean-Baptiste Onofré <[email protected]>:
Thanks Milen,
it's an open place to discussion. We just share standpoints and opinions:
that's the key part !!!
My goal is to give more traction on Karaf by providing easier
We all provide valid points, but I think we are not the most setted to
argue as we are deeply involved in OSGi and Karaf. The karaf-boot proto
came when discussing with new Karaf users, coming from "outside" of OSGi,
or people that decided to use spring-boot (even if they like a lot Karaf),
just because it's easier. It's hardly frustrating for us as we just need
some tooling to provide even more traction. On the container side, I think
Karaf is already great, and answers all needs. The part where we should
improve what we deliver is around developer tooling: easier, faster, key
turn.
If karaf-boot will be a success, I don't know (who knows ? ;)). But
anyway, it brings points, questions, and identify some missings in the
current picture.
My $0.01 ;)
Regards
JB
On 09/10/2015 08:02 PM, Milen Dyankov wrote:
Well I was just referring to your example but I get your point. Which
reminds me of EnRoute <http://enroute.osgi.org/> project which despite
the
big names and the most popular OSGI build tool behind it, doesn't seem to
get as much traction as I expected!
That said, I really admire your enthusiasm and wish KarafBoot can be more
successful that that. I'm not trying to discourage you! Just it seams what
you are after is something that other people have tried already with
questionable success.
Best,
Milen
On Thu, Sep 10, 2015 at 7:22 PM, Jean-Baptiste Onofré <[email protected]>
wrote:
And how to you deal with jpa, jta, rest, etc with SCR annotations ?
Regards
JB
On 09/10/2015 07:16 PM, Milen Dyankov wrote:
So correct me if I'm wrong but if I get the sample you provided in the
first mail and replace:
- the parent pom with "maven-bundle-plugin"
- @Bean with @Component
- @Init with @Activate
wouldn't that have the exact same end result? I mean it obviously differ
in
terms of what gets generated (Blueprint vs DS) but form end user
perspective there is no difference, right?
On Thu, Sep 10, 2015 at 6:55 PM, Jean-Baptiste Onofré <[email protected]>
wrote:
Hey Milen,
Actually, there's too part:
1/ karaf-boot-starter will do the ready to start artifact, embedding
karaf, but it's another point
2/ the value of karaf-boot annotations and plugin is first to simplify
the
bundle/artifact ready to be deploy-able into Karaf (generate the
"plumbing"
easily for developers).
Regards
JB
On 09/10/2015 06:50 PM, Milen Dyankov wrote:
" ... that you deploy in Karaf ..."
OK may be I misunderstood the concept. I thought the result is
standalone
executable JAR, thus my comments above. If on the other hand I need to
install Karaf and then deploy my services into it I really don't see
how
it
differs form what people are doing now?
I'm sorry if I'm not making much sense. I didn't have the time to
experiment with your code and samples so may be I'm missing an
important
peace here.
Best,
Milen
On Thu, Sep 10, 2015 at 6:27 PM, Jean-Baptiste Onofré <
[email protected]>
wrote:
Allow me to disagree: Karaf is a perfect container for microservices.
Image to create a microservice (using karaf-boot) that you deploy in
Karaf
and use such service in another microservice, all wired with OSGi
service
and Karaf: we leverage OSGi/Karaf as a microservices container.
But even without talking of microservices, new developers to Karaf
(and
OSGi generally speaking) are frustrated by the effort on non business
code
to do (I have to write an Activator, or a descriptor, etc, etc).
So, a tooling to simplify this is still a valid addition IMHO.
Regards
JB
On 09/10/2015 06:23 PM, Milen Dyankov wrote:
I might be wrong but I think the whole success of SpringBoot (apart
from
having the "Spring" in it) is the microservices hype!
it's quick and easy but most usecases follow the "create one (or
very
few)
service(s), pack them as single executable and access them via REST"
pattern. We can obviously do the same with OSGi and Karaf in
particular
but
personally I think this makes absolutely no sense. In such approach
one
in
not benefiting form OSGi almost at all. Honestly speaking I would
argue
that if one does not understand how OSGi service layer works
(regardless
of
the framework used to register/access services) it makes no sense to
use
OSGi at all.
Just my 2 cents!
Regards,
Milen
On Thu, Sep 10, 2015 at 6:08 PM, Christian Schneider <
[email protected]> 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
all
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
to
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 of
cxf
or
aries. Aries supports a very nice approach for injections, jpa and
jta.
Why should it make sense to recreate that?
Aries blueprint also has annoation support even in two flavors
(CDI,
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 on
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 (it's
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
set.
One of the purpose of karaf-boot annotations is to "abstract"
the
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
both:
- providing a ready to use parent pom allows developers to
create
a
very simple pom.xml where all plugins and dependencies are
already
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. The
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 the
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, simply
destroy
the
bean / service and recreate it the dependencies are still met
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 if
possible. I'm
not very familiar, but this is less invasive.
The real problems will come with the support of higher level
annotations
for JAXRS, JPA, etc...
Not really sure how to handle those yet...
2015-09-09 16:32 GMT+02:00 Jean-Baptiste Onofré <
[email protected]
:
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, etc).
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 different
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 bundle,
standard
jar is
fine.
* karaf-boot (coming with karaf-boot-parent) provides
annotations
that you
use directly in your business code (like @Bean, @Service,
@Reference,
@Inject, etc): again, your focus on your code, karaf-boot
deals
with
the
plumbing.
* karaf-boot-maven-plugin (coming with karaf-boot-parent) scan
the
classes
and generate a blueprint XML. For now, I'm using blueprint
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";
xmlns:xsi="
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. The
karaf-boot-maven-plugin will generate the blueprint descriptor
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,
pax-exam,
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 in
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
features,
kar,
profile.
Thoughts ?
Thanks,
Regards
JB
--
Jean-Baptiste Onofré
[email protected]
http://blog.nanthrax.net
Talend - http://www.talend.com
--
Jean-Baptiste Onofré
[email protected]
http://blog.nanthrax.net
Talend - http://www.talend.com
--
Jean-Baptiste Onofré
[email protected]
http://blog.nanthrax.net
Talend - http://www.talend.com
--
Jean-Baptiste Onofré
[email protected]
http://blog.nanthrax.net
Talend - http://www.talend.com
--
Jean-Baptiste Onofré
[email protected]
http://blog.nanthrax.net
Talend - http://www.talend.com
