As we continue with our work splitting the WildFly code base into a core
repo and then separate repos related to sets of features that we need to
solidify the contracts between the various features and between features
and the core.
I've taken a crack at an initial design document on this: see . We
also need to do the practical work of identifying the various
dependencies between our existing subsystems, see  for a start on that.
I'd love to get feedback on this thread regarding the proposed design,
as well as get direct edits on the  doc to flesh out the existing
A capability is a set of functionality that becomes available when a
user triggers it by including some configuration resource or attribute
in the management model.
We'll identify capabilities via two strings: the name of the providing
subsystem and then a capability name. A null subsystem name means a core
capability; a null capability name means the base capability of the
Capabilities will also declare the identifiers of any other capabilities
There are two use cases for this capability/requirement data:
provisioning (hopefully) and runtime.
Hopefully this information can be used by provisioning tooling when
building up a configuration document for the server/domain it is
provisioning. So instead of always including a stock configuration for a
subsystem, allow the user to tailor it a bit by declaring what
capabilities are required.
At runtime, when the configuration model is updated in such a way that a
capability is now required, the OSH that handles that update will
register the capability with the management layer in the MODEL stage. At
the end of the MODEL stage the management layer will resolve all
provided and required capabilities, failing the op if anything required
Thereafter, in the RUNTIME stage an OSH that needs a capability from
another subsystem or the core can request an object implementing the API
for that capability from the OperationContext.
I've thought a lot more about the runtime use case than I have about the
provisioning use case.
Senior Principal Software Engineer
JBoss by Red Hat