1. and 4. could be integrated with something like this (from HTML5 Boilerplate)
@<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.0/jquery.min.js"></script>
<script>window.jQuery || document.write('<script src="js/vendor/jquery-1.8.0.min.js"><\/script>')</script>@

2. The first line of the above mentioned code could be dynamic, which is generated depending on the settings in the administration.
There could be something like a pulldown (just local, jquery, microsoft, google, etc.)

3. Hm, well an automatic detection could be tricky. Example: jQuery updates to jQuery 2.x which possibly remove some function or change some function definition. This could break some features. I would prefer, that the developers choose which version should be used or not.
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Don't forget that Redmine can be deployed on a LAN not connected to the Internet.
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Etienne Massip wrote:
> Don't forget that Redmine can be deployed on a LAN not connected to the Internet.
Wouldn't that match case no 4?
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> 3. Hm, well an automatic detection could be tricky. Example: jQuery updates to jQuery 2.x which possibly remove some function or change some function definition. This could break some features. I would prefer, that the developers choose which version should be used or not.

I mean what versioin of lib we get from CDN should be same as the version from local bundled.
so it is same API whatever from CDN or local.
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Etienne Massip wrote:
> Don't forget that Redmine can be deployed on a LAN not connected to the Internet.

Well this would be handled by my mentioned code above. If the extern server isn't available, the local code would be handled.
OR:
See my point two. If the user selects "none", just the local source would be used.
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I'm not sure Redmine should handle CDN configuration; administrators who want to have assets delivered by CDN should already be able to do such with some config:

<pre><code class="ruby">
ActionController::Base.asset_host = Proc.new { |source|
if source ~= /.*jquery.*/
"//ajax.googleapis.com/ajax/libs/jquery"
end
}
</code></pre>

(this is a hand-written untested probably nonfunctional example)

You can add fallback mechanism, etc.

See http://api.rubyonrails.org/classes/ActionView/Helpers/AssetTagHelper.html.

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JQuery and JQuery-UI are merged in Redmine assets so it wouldn't work. It's hacky anyway and would make the upgrade process painfull. That's the purpose of this request to make using a CDN straightforward.
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Jean-Philippe Lang wrote:
> JQuery and JQuery-UI are merged in Redmine assets so it wouldn't work.

That was a non-functionnal example for demonstration purpose.

> It's hacky anyway

It's Rails configuration?

> and would make the upgrade process painfull.

Why would it be? Could be in @config/additional_environment.rb@, couldn't it?

> That's the purpose of this request to make using a CDN straightforward.

IMHO this should be handled by the Rails stack since it can be, rather than Redmine.

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Sure, you can do pretty much everything in @additional_environment.rb@ if you know about Rails configuration (which changes quite often BTW), Ruby, regexp and all but that's not what we can call "configuration". What I see here is a way to enable a CDN by simply uncommenting something like @jquery_cdn: google@ in @configuration.yml@.
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