Re: [pde-dev] Target Platform question

[Jeff McAffer <jeff@xxxxxxxxxxxxxxxxx>]

This arises from usecases where the target platform does not need to be "runnable" or consistent in any way. For example, the "Target Component" features that are provided in the Target Platform Components category of the Helios repo are not intended to be consistent or runnable.  They may include overlapping and even conflicting bundles. They may also include a very wide range of functionality only some of which would be useful to any particular product/scenario. Following all dependencies would pull in too much (e.g., add the whole IDE when doing RCP development).

Following this workflow should be the logical equivalent to getting the feature zip and adding it to the target. No more. No less. Feature zips coming out of the build contain only the elements that were *included* (transitively) in the feature. One characteristic of inclusion is the fact that precise version numbers are used.  That is, version X of feature F is exactly the *specific* things that it includes. It may happen to require some other things but those are not part of F. So in the absence of further information in the p2 metadata regarding what is included vs required, strict version ranges fit the bill.

In this scenario the only downside is that if someone happened to make a *requirement* in a feature and set the match rule to "perfect", those elements would be added to the target. I suspect that the use of perfect match is vanishingly small so this should not be a widespread issue.

I did see an issue the other day in the EMF SDK where the feature spec'd inclusion but part of their build was changing the expected precise version numbers to a wider range. This is a semantic bug in their build. When a developer says that F includes bundle B, the semantics are that it is a specific version of B.  That is why feature inclusion does not allow for ranges or match rules. We can certainly review features and look to have a new construct with different semantics but for now, the p2 metadata has to match the expected semantics expressed in the features.

Jeff

On 2010-05-27, at 3:50 PM, Thomas Hallgren wrote:

> Hi,
> 
> I was recently made aware that if I provision a target platform with "Include required software" unchecked, the slicer used will only follow consider requirements with strict version ranges. I fail to see the logic in that. Can someone please explain why that is?
> 
> Regards,
> Thomas Hallgren
> 
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