Ony batch api needs to be added as dependency to all deployed apps. Batch impl modules should not be exposed to application deployments.

from IRC discussion on 11/19/2013:

10:57:05 - Nihility: […] currently we are stuffing batch implementation details into every module thats bad
10:57:29 - Nihility: cfang: jamezp_afk the only deps that a user deployment should have is on APIs
10:57:50 - Nihility: cfang: jamezp_afk the APIs then depend on an impl either dynamically or in their module.xml

10:58:55 - Nihility: cfang: jamezp_afk its ok to add the APIs to every deployment
10:58:55 - dmlloyd: not implementation modules
10:59:01 - cfang: Nihility: I recall we did come up with some coarse grained logic to reduce the impact

11:01:25 - dmlloyd: cfang, but the point is that the impl modules should not be on any application at all, batch or not
11:02:06 - Nihility: cfang: right the rule is basically a propagation rule. The user only sees what it can access, which are APIS, the APIs can see impl classes and thats isolation
11:02:33 - Nihility: cfang: its the reason that a user, for example can use their own XML parser
11:03:10 - Nihility: cfang: we have some exceptions because third party code isn't always correct
11:03:34 - Nihility: cfang: but we should strive for at least our code to be properly isolated. It's not urgent but it has something we need to fix