2

We are building a product that uses the apache hadoop & hbase frameworks for handling some of our big data requirements. We are also using Oracle for our reporting requirements. We are keen to go with the OSGi way of bundling our software to take advantage of the remote deployment,service management & loosely coupled packaging features that OSGi containers offer.

We have a few doubts in this area:

  1. When it comes to our own Java apps, we now know how to create OSGi bundles out of them and deploy them over OSGi containers. But how do we handle Java based 3PPs that have a clustered architecture, for example HBase/Hadoop? We saw that Fuse Fabric has created a Hadoop (actually only HDFS not Map Reduce) bundle, but in general how do you go about creating bundles for 3PP's?

  2. How do we handle non-java based 3PPs like for example Oracle. Should we create a OSGi bundle for it and deploy over OSGi or should we install these 3PP's outside of OSGi and write some monitoring scripts that are triggered over OSGi to track the status of these 3PP's? What are the best practices in this area?

  3. Are all bundles launched over OSGi container (like Karaf) run within the same single JVM of the container? Some of our applications and 3PPs are huge and we may run into heap/GC issues if all of them are run inside a single JVM. What are the best practices here?

Thanks & Regards Skanda

il_guru
  • 8,383
  • 2
  • 42
  • 51
user1853204
  • 99
  • 1
  • 2

2 Answers2

0

  1. Creating bundles from non-OSGi libraries can be as simple as repackaging it with an appropriate manifest (there are tools for that, see below), but it can also become very difficult. OSGi has a special class-loading model, and many Java EE libraries that do dynamic class-loading don't play well with that.

  2. I am not sure what you mean here. Theoretically OSGi supports loading native libraries using the Bundle-NativeCode manifest-header, but I have no experience with that.

  3. Normally all bundles are run in the same virtual machine. However, Karaf supports clustering through Cellar, I don't know about other containers though.

Tools for wrapping 3rd-party libraries

In general you can use bnd for this (the tool of choice when it comes to automated generation of OSGi-bundle manifests). PAX-URL offers the wrap protocol-handler, which is present by default in Karaf. Using that, wrapping a library can be as simply as that (e.g. from the Karaf-command line, or a feature-descriptor):

wrap:file:path/to/library
Arjan Tijms
  • 37,782
  • 12
  • 108
  • 140
Björn Pollex
  • 75,346
  • 28
  • 201
  • 283
0

The case of Oracle and most other db libs is simple. You can use the wrap protocol of pax url. Unter the covers it uses bnd with default options. I have a tutorial for using dbs with Apache Karaf.

In general making bundles out of third party libs can range from easy to quite complicated. It mainly depends on how much dirty classloading tricks the lib uses. Before you try to bundle stuff yourself you should look if there are ready made bundles. Most libs today either come directly as bundles or are already available as bundles from some source. For example the servicemix project creates a lot of bundles. You can ask on the user list there if something is available.

Christian Schneider
  • 19,420
  • 2
  • 39
  • 64