Hi, after the good talks and nice conversations at EclipseCon and OSGi Community Event this year, I thought of trying to make the Eclipse Platform code a "better OSGi citizen".
Unfortunately there seem to be some configurations that can't be solved easily, namely split packages in very basic bundles. And the fact that every change needs to consider to no break existing consumers. As you probably know, in Eclipse RCP development (even in the Platform itself) the usage of Require-Bundle is very common and widely used. Additionally some bundles re-export the imported bundles. From what I have read in the specification, re-exports can lead to startup performance issues as ClassNotFoundExceptions can occur while searching a class down the bundle dependency graph. One of the first issues I came across was the org.eclipse.core.runtime bundle and the org.eclipse.core.runtime split package. There are some bundles in Equinox that also export org.eclipse.core.runtime (e.g. org.eclipse.equinox.common). They specify a mandatory directive to be able to deal with the split packages. org.eclipse.core.runtime has Require-Bundle statements to that bundles and exports the package without an attribute. So far it sounds to me like the correct approach to deal with the split packages using an aggregator bundle. Unfortunately org.eclipse.core.runtime requires several bundles and even worse re-exports all of them. I was asking myself if the bundle setup could be changed in a way that it follows the OSGi best practices by still keeping the backwards compatibility (people that are using Require-Bundle should not suffer from changes but be able to go for the correct way). First I wanted to change the Require-Bundle statements in org.eclipse.core.runtime with proper Import-Package statements. But that leads to issues with the split packages. The package needs to be imported from several other bundles and then exported without a mandatory directive. AFAIU that doesn't work as that would be multiple imports of the same package (although different mandatory attributes). Correct? Additionally I think there will be a backwards compatibility issue because of the re-exports. For example via Require-Bundle org.eclipse.equinox.common with re-export, the package org.eclipse.equinox.event is also available by using Require-Bundle on org.eclipse.core.runtime. So I thought of also exporting the package that was imported. Surely not the best practice, I know. But I have seen that Bndtools supports this while PDE is showing an error when this is tried. So I'm also a bit confused whether that is allowed and supported (I think I have seen this in the spec also) or if I misunderstand the re-exports. While writing this I think I should not look at org.eclipse.core.runtime but at the platform bundles that are consuming the bundle and change them to use the correct Import-Package statements. But well, any insight and opinions are welcome. Greez, Dirk
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