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From Daniel Las <daniel....@empirica.io.INVALID>
Subject Re: [PROPOSAL] Disable autoRefresh on features service by default and simple optional features service
Date Fri, 08 Jan 2021 07:16:47 GMT
Hi,

It looks like some kind of backward incompatible change introduced within
patch version change. I personally would like to keep auto refresh "on" by
default as this is expected/desired behavior for me.

Regards

pt., 8 sty 2021 o 07:31 Jean-Baptiste Onofre <jb@nanthrax.net> napisał(a):

> Hi everyone,
>
> We got several user feedback, complaining about unexpected and cascaded
> (unrelated) refresh while installing features.
>
> As reminder, a refresh can happen when:
> - bundle A imports package foo:1 and a bundle provides newer foo package
> version. In that case, the features service will refresh A to use the
> newest package version.
> - bundle A has an optional import to package foo and a bundle provides
> this package. In that case, the features service will refresh A to actually
> use the import as it’s a "resolved" optional.
> - bundle A is wired to bundle B (from a package perspective or
> requirement) and B is refreshed. In that case, the features service will
> refresh A as B is itself refreshed (for the previous reasons for instance).
> This can cause "cascading" refresh.
>
> A refresh means that a bundle can be restarted (if the bundle contains an
> activator or similar (DS component, blueprint bundle)).
>
> In this PR https://github.com/apache/karaf/pull/1287, I propose to
> introduce a new property autoRefresh in etc/org.apache.karaf.features.cfg
> to disable the auto refresh by the features service (and let the user
> decides when he wants to trigger refresh with bundle:refresh command for
> instance).
> I propose to keep autoRefresh=true on 4.2.x and turn autoRefresh=false on
> 4.3.x.
>
> Thoughts ?
>
> On the other hand (and to prepare the "path" to Karaf5), I have created a
> new "simple features service" (PR will be open soon) that:
>
> - just take the features definition in order (ignoring start level)
> - ignore requirement/capability (no resolver)
> - no auto refresh
>
> Basically, if you have the following feature definition:
>
> <feature name="foo" version="1.0">
>   <feature>bar</feature>
>  <bundle>A</bundle>
>  <bundle>B</bundle>
> </feature>
>
> The features service will fully install/start bar feature first, then
> bundle A, then bundle B.
> To use this "simple features services, you just have to replace
> org.apache.karaf.features.core by org.apache.karaf.features.simple bundle
> in etc/startup.properties (or custom distribution).
>
> It’s similar to the Karaf 5 extension behavior (I will share complete
> details about Karaf 5 and its concepts (module, extension, …) very soon,
> but that’s another thread ;)).
>
> The big advantages of this approach is:
> - predictable/deterministic provisioning (if it works fine, it works again)
> - faster deployment (I estimated the gain to about 70%)
>
> Thoughts ?
>
> If you agree, I will move forward on both tasks.
>
> Thanks,
> Regards
> JB
>


-- 
Daniel Łaś
CTO at Empirica S.A.
+48 695 616181

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