[wildfly-dev] selecting packages from feature-packs

[Alexey Loubyansky]

On 10/21/2016 03:50 PM, Brian Stansberry wrote:
>
>> On Oct 19, 2016, at 7:27 AM, Alexey Loubyansky <alexey.loubyansky at redhat.com> wrote:
>>
>> Me and Stuart have been thinking about how to express feature-pack
>> package selection in an XML. Each one came up with a proposal but we
>> appear to have slightly different preferences. In case anybody has an
>> opinion or a better suggestion, please, share.
>>
>> Brief description: feature-pack consists of packages. A package is a
>> unit of content. So a set of packages determines the target installation
>> content-wise. Feature-pack has a set of default packages. These are the
>> packages that get installed by default, i.e. when the user installs the
>> feature-pack w/o specifying any package preferences. In addition to the
>> default ones a feature-pack may contains non-default packages, these are
>> present in the feature-pack but will be installed only if the user
>> explicitly asks for them.
>> So, the question is how to express these package preferences in an XML.
>>
>> Proposal 1.
>>
>> - include-default flag (element or attribute) which defaults to true
>> (meaning the default packages will be included by default);
>>
>
> Th “include” element is still supported here, right? So, I can get all the default ones and then use include elements to pull in additional ones.

Right.

>> - if include-default is false (meaning nothing is installed by default),
>> then 'include' element can be used to pick the specific packages
>> (default and non-default ones) to be installed;
>>
>> - otherwise (when include-default is true) 'exclude' element can be used
>> to exclude specific undesired default packages.
>>
>
> Can “exclude” be used to exclude dependencies? So I want “a” but not its dependency “b”? If the answer is yes for optional dependencies, what if the dependency isn’t optional?

Yes, it can be used to exclude dependencies. If a required 
(non-optional) dependency is excluded, that'll be an error.

>> Proposal 2.
>>
>> - exclude element - applicable to any package and means do not install
>> the package (and its dependencies);
>>
>> - include element - applicable to non-default packages and means do
>> install the non-default package (and its dependencies);
>>
> What happens if it’s used for a default package? The tool forgives this, right?

That would be redundant, of course. We could ignore that or issue a warning.

>> - pick element - applicable to any package and means install only the
>> picked package(s)
>
> and it’s dependencies? If yes, all its dependencies or only non-optional?

No, the dependencies would have to be picked explicitly. Otherwise, we 
have to allow exclude and include to be used in combination with pick 
which will look too confusing.

>> ignoring other default and non-default ones. pick
>> cannot be used in combination with exclude and include.
>>
>>
>> Basically, 'include' and 'exclude' in both proposals are practically the
>> same. The difference is how the picking is expressed. In the first one,
>> everything is explicitly excluded and then the desired ones are
>> explicitly included, in the second one the desired ones are simply
>> explicitly picked.
>>
>
> The answers to my questions on Proposal 1 impact the semantics of include/exclude in different cases, so I’ll defer expressing an opinion for now. :)

Thanks,
Alexey

>
>>
>> Thanks,
>> Alexey
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>