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Re: [p2-dev] P2 default fragment requirements

Vladimir,
thanks for your questions.

Regarding http://wiki.eclipse.org/Equinox/p2/P2_Fragments - the name is unfortunate. It's a secondary mechanism for assembling installation from "Installation Fragments". I expect you have no interest in it.

I think that the main reason you have hostRequirements and requires are because hostRequirements are usually smaller than required. hostRequirements says where to attach the fragment, and required means what the fragment needs.

They are identical because P2 will minimize the installation, hence the same bundle used in hostRequirements will be used for satisfying requires. I think the protocol could be improved here, but there is almost no gain here, so I'd not expect changes.

Best regards,


On Thu, Feb 27, 2014 at 5:57 PM, Vladimir Prus <vladimir@xxxxxxxxxxxxxxxx> wrote:

Hi,

I'm looking at http://wiki.eclipse.org/Equinox/p2/Setting_Start_Levels and it mentions that default fragment
is added to all IUs, and in particular it contains this:

 Â<hostRequirements size='1'>
   <required namespace='org.eclipse.equinox.p2.eclipse.type' name='bundle' range='0.0.0' multiple='true' greedy='false'/>
 Â</hostRequirements>

 Â<requires size='1'>
   <required namespace='org.eclipse.equinox.p2.eclipse.type' name='bundle' range='0.0.0' multiple='true' greedy='false'/>
 Â</requires>

What exactly is the role of the 'requires' element? It is rather board requirements already, and then this fragment
is added to every other IU, so effectively every bundle IU has a requirement that can be satisfied by any other
bundle IU, and the practical impact of this is rather unclear to me.

Unrelatedly, looking at http://wiki.eclipse.org/Equinox/p2/P2_Fragments is seems that 'fragments' is used in completely
different way there? What is the current primary meaning?

Thanks in advance,

--
Vladimir Prus
CodeSourcery / Mentor Graphics
http://www.mentor.com/embedded-software/
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--
Krzysztof Daniel
https://twitter.com/kda