The goal of this proposal is to define clear lines between modules of geode, so that each piece can be tested independently by mocking out the other modules.

In order to accomplish that goal, each module needs to have a clear API for the rest of the system to use, and tests within that module that cover all of the features of the API.

Here's a start at listing the modules and their dependencies. 

Each module should have at least it's own package(s), if not be in a separate gemfire- gradle module. Anything that is not part of the API for that module should only be package visible.

Here is a high level view of the interfaces for each module and some of the changes that need to be made

Statistics

Package:internal.statistics?

API interfaces/classes: Statistics, StatisticsFactory, StatisticsManager

Required changes: Move into a separate package. Pull the code out of InternalDistributedSystem (it currently implements StatisticsFactory) into a separate class.

Messaging

Package:distributed.internal?

API interfaces/classes: InternalDistributedMember, DM, InternalDistributedSystem, MembershipListener

Required Changes: InternalDistributedMember and InternalDistributedSystem should be interfaces, not concrete classes. They should only have the methods that are required by the rest of the system.

Persistence

Package: internal.cache.persistence

API interfaces/classes: InternalDiskStore, DiskStore, DiskRegionView, DiskId

Required Changes: InternalDiskStore is new interface.