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From Marcel Offermans <marcel.offerm...@luminis.nl>
Subject Re: Using the Sling OSGi Installer?
Date Mon, 28 Nov 2011 18:01:32 GMT
On Nov 28, 2011, at 16:35 PM, Carsten Ziegeler wrote:
> 2011/11/27 Marcel Offermans <marcel.offermans@luminis.nl>:
>> 
>> I guess this is a difference between ACE (or rather deployment packages) and the
Sling installer. If you have an application installed and there is an update for bundles A,
B and C (and we assume there is a bug in B) then ACE will:
>> 
>> Start a transaction, install A, install B, discover that that fails and rollback
B and A to end up in the original situation again.
>> 
>> And from what I understand, Sling will:
>> 
>> Install A, install B, discover that that fails, install C, and then keeps retrying
B.
>> 
>> My concern is that probably, with only A and C installed, the overall application
will not work that well, whereas if you roll all changes back, the chances of ending up with
an application that works are a lot better.
> 
> Yes, that's a basic difference - but as long as you're using
> deployment packages with the Sling installer, you're fine. So your
> deployment package contains bundles A, B and C and if installation of
> B fails, the deployment package installation is stopped/rolled back.

True!

> The only difference is, Sling tries to reinstall the deployment
> package.

Actually, I forgot to explicitly mention that, but the default behavior of the ACE management
agent is the same, it will periodically keep retrying.

> If you're using single bundles which are installed directly, you're right.
> 
>> Yes. As soon as you allow more than one version of a bundle to be installed at the
same time, you end up with problems because you cannot identify in the case of an update,
which is an update of which. This, in my opinion, is a "bug" in the OSGi specification, especially
now that the 4.3 spec will even allow you to install the same version multiple times. Luckily,
in real life, this situation rarely occurs (appearantly).
> Yepp, when it comes to bundles, the Sling installer does not allow to
> install the same bundle in different versions (based on the symbolic
> name of the bundle)

Out of interest, did you ever run into issues with this in practice?

Greetings, Marcel


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