Coming in Karaf 3.0.0: new enterprise JNDI feature

In previous Karaf version (2.x), the JNDI support was “basic”.
We just leveraged Aries JNDI to support the osgi:service JNDI scheme to reference the OSGi services using JNDI name.

However, we didn’t provide a fully functionnal JNDI initial context, nor any tooling around JNDI.

In part of the new enterprise features coming with Karaf 3.0.0, the JNDI support is now more “complete”.

Add JNDI support

As most of the other enterprise features, the JNDI feature is an optional one. It means that you have to install the jndi feature first:

karaf@root()> feature:install jndi

The jndi feature installs several parts.

Ready to use initial context

Like in previous version, Karaf provides a fully compliant implementation of the OSGi Alliance JNDI Service Specification. This specification details how to advertise InitialContextFactory and ObjectFactories in an OSGi environment. It also defines how to obtain services from services registry via JNDI.

Now, it’s possible to use directly the JNDI initial context. Karaf now provides a fully functionnal initial context where you can lookup both the osgi:service scheme or a regular JNDI name.

You can do:

Context context = new InitialContext();MyBean myBean = (MyBean) context.lookup("my/bean/name");

You can use the osgi:service scheme to access to the OSGi service registry using JNDI:

Context context = new InitialContext();MyBean myBean = (MyBean) context.lookup("osgi:service/mybean");

JNDI Service, Commands and MBean

Karaf 3.0.0 provides a OSGi service dedicated to JNDI.

The interface of this JNDI service is org.apache.karaf.jndi.JndiService and it’s registered when installing the jndi feature.

You can manipulate the JNDI service using shell commands.

You can list the JNDI name using jndi:names:

karaf@root()> jndi:namesJNDI Name         | Class Name                                    ------------------------------------------------------------------osgi:service/jndi | org.apache.karaf.jndi.internal.JndiServiceImpl

You can create a new JNDI name using anoher one (a kind of alias) using the jndi:alias command:

karaf@root()> jndi:alias osgi:service/jndi local/service/jndikaraf@root()> jndi:namesJNDI Name          | Class Name                                    -------------------------------------------------------------------osgi:service/jndi  | org.apache.karaf.jndi.internal.JndiServiceImpllocal/service/jndi | org.apache.karaf.jndi.internal.JndiServiceImpl

For instance, here, we bind a name from the “special” osgi:service scheme as a “regular” JNDI name.

You can directly bind a OSGi service (identifiy by its service.id) with a JNDI name:

karaf@root()> jndi:bind 344 local/service/karkaraf@root()> jndi:namesJNDI Name         | Class Name                                    ------------------------------------------------------------------local/service/kar | org.apache.karaf.kar.internal.KarServiceImpl  osgi:service/jndi | org.apache.karaf.jndi.internal.JndiServiceImpl

You can alias the local/service/kar name with directly service/kar:

karaf@root()> jndi:alias local/service/kar service/karkaraf@root()> jndi:namesJNDI Name         | Class Name                                    ------------------------------------------------------------------local/service/kar | org.apache.karaf.kar.internal.KarServiceImpl  service/kar       | org.apache.karaf.kar.internal.KarServiceImpl  osgi:service/jndi | org.apache.karaf.jndi.internal.JndiServiceImpl

You can unbind the service/kar name:

karaf@root()> jndi:unbind service/karkaraf@root()> jndi:namesJNDI Name         | Class Name                                    ------------------------------------------------------------------local/service/kar | org.apache.karaf.kar.internal.KarServiceImpl  osgi:service/jndi | org.apache.karaf.jndi.internal.JndiServiceImpl

You can get all JNDI names, and manipulate the JNDI service using a new JMX JNDI MBean. The object name to use is org.apache.karaf:type=jndi,name=*.

Conclusion

One of our purpose for Karaf 3.0.0 is to provide more services, commands, MBeans to move Karaf as a more complete full enterprise OSGi container.

If we already provide a bunch of features, a lot are not really “visible” to the end users due to some “missing” commands or MBeans.

It’s a key point for Karaf 3.x releases.

Comments

Post a Comment

Popular posts from this blog

Exposing Apache Karaf configurations with Apache Arrow Flight

Image
This blog post shows how to use Apache Arrow and Arrow Flight in Apache Karaf runtime. The code base is available here: https://github.com/jbonofre/karaf-arrow . Apache Arrow ? Apache Arrow is composed by: The Arrow format (specification). Format implementations with different languages (C, Java, Go, Rust, ...). Extra subprojects like Flight, Flight SQL, ADBC, nanoarrow, ... Apache Arrow format is a in-memory columnar format, super efficient for scanning and iterating a large chunks of data. In traditional memory buffer, we focus on "row". Apache Arrow format "groups" data per column, which is much more efficient on modern CPUs/GPUs. The Apache Arrow format is basically a specification. We have several implementations for this specification: C C++ C# Go Java Python Ruby Rust As the purpose of this blog post is to show Apache Arrow in Apache Karaf, we will use Arrow Java. In addition, Apache Arrow also provides several...
Read more

Getting started with Apache Karaf Minho

Image
Apache Karaf Minho Apache Karaf Minho is a new runtime, completely created from scratch. The objectives are: super easy to use and run ligtning fast, including GraalVM support Kubernetes compliant to be easily used on the cloud helping to optimize cloud costs by supporting applications colocation providing turnkey services allowing you to create Minho applications in a minute Minho is composed by: minho-boot is the core of Minho. It contains the runtime launcher and the core services (service registry, lifecycle service, configuration service, ...). minho-* services provided additional functionnalities in the runtime. You can use these services to create your own services, it's also where you will find the services managing sepcific kind of applications, allowing colocation. minho-tooling optionally provide convenient tools to create your own runtime. It includes minho-maven-plugin for instance. In this blog post, we will take a quick tour on A...
Read more

Using Apache Karaf with Kubernetes

Image
In a previous blog post ( http://blog.nanthrax.net/?p=893 ), I introduced the “new” docker support in Karaf and the use of Karaf static distribution. This post follows the previous one by illustrating how to use Karaf docker image with a Kubernetes cluster. Preparing Karaf static docker image As in the previous blog post, we are preparing a Karaf static distribution based docker image. For this blog post, I’m using the example provided in Karaf: https://github.com/apache/karaf/tree/master/examples/karaf-docker-example/karaf-docker-example-static-dist . I’m just building the distribution as usual: karaf-docker-example-static-dist$ mvn clean install Preparing kubernetes testing cluster For this blog, I’m using a minikube installed locally. The installation is pretty simple: Download minikube from https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64 Rename minikube-linux-amd64 as minikube Copy minikube in your path, for instance /us...
Read more