While the DirectoryProvider notion will probably stay for longer, we should simplify the configuration phase by providing more IndexManager implementations which define the worthwhile combinations of configuration settings.

For example we could have:

• MasterJMSIndexManager to combine
• SlaveJMSIndexManager
• AutoJGroupsIndexManager to combine the JGroups backends with master/slave directory providers and their automatic alternating.
• NRTIndexManager - combined with FSDirectoryProvider only so we automatically imply that NRT is not compatible with the remoting backends.
• MemoryIndexManager - replacing capability to configure RAMDirectory directly, also we could enable NRT by default.

Bonus requirement: for sake of testability of components we probably want a way to still combine elements freely.
For sake of performance diagnostics, users will need to be able to unlock specific flexibility too: for example enabling blackhole should always be an option for all IMs.. should it be a specific blackhole attribute shared by all IMs or should we have a more generic override capability?

Ideally the InfinispanIndexManager would be added on the list.