# MQTT v5 server side sessions and routing
MQTT v5 session and topic routing - embeddable in Erlang projects.
This library handles pools of MQTT sessions.
Transports (connections) attach to MQTT sessions to relay packets.
The sessions handles packets, queues, and a user-context state.
Access control and authentication is handled with a runtime module.
This module is configured in the `mqtt_sessions` application env key `runtime`.
The default and example runtime is `src/mqtt_sessions_runtime.erl`.
Note that this library does not handle TCP/IP connections. It handles the
complete MQTT session logic. Other libraries are used for transporting the
MQTT packets to/from external clients.
When a subscription is made to a $SYS topic the subscriber is mapped to
the default pool. This makes it possible to share system information
between different pools.
1. Add protections
- Max packet size
- Max memory voor retained
- Max number of pending messages (drop QoS 0)
- Max pending acks (flow control)
- Rate limiting
2. Add instrumentation
- Number of sessions
- Number of connected sessions
- Number of packets sent / received
- Connect rate
- Memory consumption of retained tables
- Sessions with biggest queues
- Sessions with largest number of packets