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From Michal Kleczek <michal.klec...@xpro.biz>
Subject Re: OSGi RFC 119 Distributed OSGi - (Was [RE: OSGi and Jini])
Date Thu, 23 Jul 2009 07:41:22 GMT
On Thursday, 23 of July 2009 06:11:01 Peter Firmstone wrote:
> HTTP codebase's are part of the problem, the URLClassLoader is fixed in the
> object's Type (class identity), which may change over time.  Michael Warres
> addressed this problem by creating a dynamic codebase service where the URL
> was a cryptographic hash of the jar file (stored data) identity.
>
> Michael made a presentation on Service based codebases, apparently not
> much code was required to implement it.  We cannot directly copy the
> code (interfaces etc) from the presentation due to copyright, although
> we can produce functionally equivalent code.
>
> http://www.jini.org/files/meetings/eighth/presentations/Warres/Warres.pdf
>

We have implemented a similar solution in XPro.
The main difference is that in our implementation there is no "put" operation 
in a ContentAddressedStore interface. In other words:
1. Each service publishes a separate ContentAddressStore and becomes its own 
codebase server.
2. You can run specialized services that cache resources from other 
ContentAddressStores to achieve HA
3. Optionally you can configure the services to act in a P2P fashion - the 
resources downloaded by a service are also published.

The main motivation behind this was to be able to run services with minimal 
dependencies on other services being available on the network.

After resolving some licencing problems (which should not be very complicated 
I think) we could contribute this code to River.

Thanks,
Michal

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