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From Felix Meschberger <>
Subject JCR Node Type Management Issues
Date Wed, 19 Sep 2007 15:11:21 GMT
Hi all,

Currently, the sling-content-jcr bundle has a ContentManagerFactory
implementation (the JcrContentHelper, used to access Sling
ContentManager instances), which listens for bundles being registered
and registers node types registered in the bundles and loads initial
content stored in those bundles. Additionally, this class cares to setup
the Sling ContentManager instances used to access the OCM functionality.

While working on the sling-event bundle, we discovered a race condition
with node type registration and repository use. To overcome this race
condition, we propose to move the node type registration part from the
ContentManagerFactory implementation to the AbstractSlingRepository
class in the sling-jackrabbit-api bundle. This class is the base class
for services registered to provide the repository. As such, this class
has contact to the repository before the service is registered or made
available to the users of the repository.

Some background information on the race condition: The JcrContentHelper
is implemented as an OSGi Component and requires a repository and as
such will only be activated when the repository is available. The
AbstractRepositoryEventHandler in the sling-event bundle also requires a
repository and is also implemented as an OSGi component. When now both
components are waiting for a repository to become available, the
AbstractRepositoryEventHandler may be activated before the
JcrContentHelper is activated and therefore, the node types required by
the AbstractRepositoryEventHandler are not available yet as the
JcrContentHandler was not able yet to register them ...

What do you think of this change ?



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