MATS remote introspection and control

[stolsvik]

Idea based on advisory topics for ActiveMQ

• Query for MatsEndpointFactories: Send message to some Topic, get reply from all MatsEndpointFactories, containing information about all endpoints and stages, their state (active or stopped), concurrency, and some metdata e.g. machine name, system name, uptime, total number of processed messages, etc.
• Query for endpoint status and stats: Send message to some endpoint-specific topic, get reply about state (active or stopped), number of processed messages, concurrency, and metadata for its factory.
• Send start/stop command to endpoint: Send message to some endpoint-specific topic, possibly with machine-specifier, asking it to stop or start consuming messages.
• .. Same for stages.
• Set concurrency for stage, endpoint and factory.