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Re: [oscar] Another alpha

On Wednesday 27 April 2005 15:44, Richard S. Hall wrote:

> Perhaps my explanation was confusing. By using that property, the
> packages listed on it are treated as actual exports of the System
> Bundle, i.e., they are treated as a normal export and thus must be
> explicitly imported by any bundle that wishes to use them. To state it
> another way, bundles are only given implicit access to java.* packages,
> all other packages must be explicitly imported, no matter what.

Ah, okay, reading it back you could interpret it both ways I guess. :)

> > - no way to update such packages

> This is true, but there isn't much I can do about that. However, at
> least now you can provide an alternative implementation, which could be
> an update. That is something you could not do before.

If you set the property and the system bundle exports a package, is there a 
way to "override" this export by providing a bundle which exports the same 
package? I mean, you can't stop the system bundle or modify its exports, so 
that might make providing updates a bit harder.

> I think the property is a way to do the same thing, albeit not dynamically.

> I am not sure that it makes sense for bundles to export system classes
> for the precise reason you mention, they don't know if they exist. I
> think it makes the most sense for the framework to do the exporting
> (e.g., via the system bundle as described). Whether or not to provide a
> mechanism to change this value dynamically is a separate issue as far as
> I can see.

Agreed, the manifest idea was not that good. But providing a mechanism to 
change the value dynamically would give you more flexibility because then you 
can let some kind of provisioning agent decide what to export and what not, 
depending on the application you are deploying. And because such an agent 
usually installs bundles, the idea for using the manifest was born.

On the other hand, these features we're discussing now are only really useful 
if they become part of some future version of the OSGi standard, otherwise 
you can't depend on them.

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