THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
1. Introduction
This service watch "/" prefix key on Etcd, so any data changes to etcd will be noticed.
Other components can subscribe/unsubscribe to the WatcherService using different key or prefix key, they can also specify which event type they are intrested, such as Put or Delete or Both.
WatcherService will send messages to subscribers when related etcd changes are got via actor message.
2. Architecture Diagram