Sylvain Wallez wrote:
Hi all,
I just found that Eclipse is moving their component container to OSGi [1]. Avalon was one of the possible candidates, but it seems that only OSGi was seriously considered [2].
OSGi was up to now mostly used in embedded systems (cars, automation), and its adoption by the Eclipse team will promote this platform to many more developpers, particularly in the J2EE world. I'm wondering [3] how this can impact the future of Avalon.
What do you think?
My initial look at OSGi is that it is solving a different set of problems than Avalon. Although with some of the work being done on the Avalon repository, that may be different now.
My perception was that OSGi was working with the JAR==component outlook, and had some nice features for loading and unloading these JARs. Avalon OTOH, was working with smaller granularity components. So, in one sense, they can work together. In fact, it might be a good marriage.
And OSGi "bundle" (that's the term for the deployment unit) can provide several services: a "BundleActivator" class inside the bundle registers the provided services (there can be several) when the bundle is loaded. Registering a service consists in registering an instance of the service interface with additionnal properties that describe the service. The lookup mechanism then allows to select a particular implementation of the service depending on property values, by using a simple LDAP-like query language.
OSGi is also very good a loading/downloading/unloading bundles.
I have the impression OSGi directly compares to Phoenix blocks (don't know about Merlin?), but it doesn't support non-singleton services like ECM or Fortress.
You can have a quick look at how it works through the very explanatory tutorial at http://oscar-osgi.sourceforge.net/tutorial/index.html
Sylvain
-- Sylvain Wallez Anyware Technologies http://www.apache.org/~sylvain http://www.anyware-tech.com { XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects } Orixo, the opensource XML business alliance - http://www.orixo.com
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