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From Tobias Bocanegra <tri...@apache.org>
Subject Re: Make "Whiteboard" accessible through ContentRepository
Date Wed, 12 Feb 2014 06:37:50 GMT

On Tue, Feb 11, 2014 at 4:38 PM, Tobias Bocanegra <tripod@apache.org> wrote:
> On Tue, Feb 11, 2014 at 1:59 PM, Jukka Zitting <jukka.zitting@gmail.com> wrote:
>> On Mon, Feb 10, 2014 at 2:25 AM, Felix Meschberger <fmeschbe@adobe.com> wrote:
>>> This thread indeed raises the question, why Oak has to come up with something
(the Whiteboard)
>>> that is almost but not quite like OSGi instead of going all the way through ?
>> This is a misunderstanding; we're not trying to reinvent OSGi.
>> The Whiteboard interface is *only* an abstraction of the whiteboard
>> pattern described in
>> http://www.osgi.org/wiki/uploads/Links/whiteboard.pdf, and is used
>> only for those cases in Oak where that pattern is useful. When running
>> in an OSGi environment, the Whiteboard simply leverages the existing
>> OSGi functionality.
>> The Whiteboard in Oak is not a generic service registry, and is not
>> supposed to become one.
> but then, why does the Whiteboard interface has a register() method?
> This indicates to me, that there is a global service registry behind
> that can be used by all other users of the whiteboard.
> Also, using the whiteboard in the tests make them very easy
> configurable and simulates a bit better how OSGi will work. for
> example in the ExternalLoginModuleTest, I can just do:
>         whiteboard = oak.getWhiteboard();
>         whiteboard.register(SyncManager.class, new
> SyncManagerImpl(whiteboard), Collections.emptyMap());
>         whiteboard.register(ExternalIdentityProviderManager.class, new
> ExternalIDPManagerImpl(whiteboard), Collections.emptyMap());
> If I need to register them with the login module, this would not work
> today, without hard wiring all possible services to the
> SecurityProvider.

addendum: If I want to achieve the same without the whiteboard, I would need to:

* Invent a new interface that allows to pass services/helpers to the
login modules. eg a LoginModuleService interface
* Create some sort of LoginModuleServiceProviderConfiguration
* Create an implementation of the above that deals with OSGi but also
can be used statically
* Add the LoginModuleServiceProviderConfiguration to
* Add the interface to my ExternalIDPManagerImpl and SyncManagerImpl
* in the login module, retrieve the
LoginModuleServiceProviderConfiguration from the SecurityProvider,
then find a service for SyncManager and

* in the non-osgi case, I would need to initialize the
LoginModuleServiceProviderConfigurationImpl myself and add the 2
services and add the config to the securityprovider.

The additional work is that I need to re-invent some sort of service
registry for the LoginModuleServiceProviderConfigurationImpl and
extend the SecurityProvider with another configuration. Also, I limit
the interfaces to be used in the LoginModules to the ones implementing
the LoginModuleService interface. you might say, this is more robust -
I say, this is just more complicated and has tighter coupling.

regards, toby

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