Before every thread would hit the database once at the start to
load the system account and user. The loaded objects are almost never
used. This change optimizes the behavior and lazy loads the system
user and account object.
ACS is now comprised of a hierarchy of spring application contexts.
Each plugin can contribute configuration files to add to an existing
module or create it's own module.
Additionally, for the mgmt server, ACS custom AOP is no longer used
and instead we use Spring AOP to manage interceptors.
The managed context framework provides a simple way to add logic
to ACS at the various entry points of the system. As threads are
launched and ran listeners can be registered for onEntry or onLeave
of the managed context. This framework will be used specifically
to handle DB transaction checking and setting up the CallContext.
This framework is need to transition away from ACS custom AOP to
Spring AOP.
