Chetan Mehrotra created SLING-2624:
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Summary: Improving Jackrabbit integration with OSGi Service
Registry
Key: SLING-2624
URL: https://issues.apache.org/jira/browse/SLING-2624
Project: Sling
Issue Type: New Feature
Components: JCR
Reporter: Chetan Mehrotra
Current Sling integration with Jackrabbit (JR) allows for simpler access to
Repository services from other bundles via the OSGi Service Registry (SR).
However to make use of OSGi services within JR is tricky. Some integration is
done wrt security but for other areas one needs to use fragments.
To simplify such integration recently a new feature was added to JR (JCR-3420)
[1] which allows for registering a custom BeanFactory with JR. This would allow
usage of services from service registry within JR. Refer to Mail thread [5] for
relevant discussion
Feature Details
===============
This feature builds up on the new module org.apache.sling.jcr.jackrabbit.base
proposed with SLING-2623.
OsgiBeanFactory
---------------
This is an implementation for the JR BeanFactory extension and acts as a bridge
between OSGi and JR. It uses a custom BeanConfigVisitor to collect all the
dependency information i.e. details about services which need to be pulled from
SR. Then it uses a ServiceTracker to track avialability of all such services.
Once all the required dependencies are found it registers itself with SR.
Once it is registered the SlingServerRepository can start
* Note - This feature has not much dependency on SLING-2623. Just that git fork
is based on the base of SLING-2623
SlingServerRepository Integration
---------------------------------
OsgiBeanFactory needs to know the repository configuration which would be used
to create the repository. Current fork impl uses one way to determine the
config (which would need to be revisited). Further SlingServerRepository now
has a reference for BeanFactory and would only be activated upon registration
of BeanFactory
Note - The current SlingServerRepository is configured as component factory
which would require a 1..1 mapping to BeanFactory. Such mapping is bit tricky
to achieve. However in most cases a Sling server has only one
SlingServerRepository. So the proposed approach *assumes* that there is a
single repository instance configured
Sample Usage
============
To demonstrate the use of such a feature I took the usecase of externalizing
the AuthorizableAction [2] in Sling env. So it should be possible to use an
OSGi service which implements the AuthorizableAction within JR. An
implementation of that is available at [4]. In the JR repository.xml we would
have an entry like show below
<AuthorizableAction
class="org.apache.jackrabbit.core.security.user.action.AuthorizableAction" />
Then the OSGiBeanFactory would obtain the instance of AuthorizableAction from
Service Registry and provide that to JR. Now any bundle can register an
instance of AuthorizableAction with SR and it would be invoked for various
callbacks from JR UserManager!!
Note about patch
===============
The patch builds up on the SLING-2623 fork. Once we have consensus upon the
approach I can extract relevant parts and propose a new patch
[1] https://issues.apache.org/jira/browse/JCR-3420
[2]
http://jackrabbit.apache.org/api/2.4/org/apache/jackrabbit/core/security/user/action/AuthorizableAction.html
[3] https://github.com/chetanmeh/sling/compare/osgi-factory4
[4]
https://github.com/chetanmeh/sling/compare/chetanmeh:jaas-osgi-adv...chetanmeh:osgi-factory4
[5] http://markmail.org/thread/3nnkygzef5dvzxod
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