In the previous chapter, we created a small static concentrator. The IoT Gateway defines a more flexible dynamic concentrator. It allows standalone modules to define new classes of nodes that can be administered through the concentrator interface. The Waher.Things.Metering library defines a data source called the Metering Topology (MeteringTopology). The Metering Topology has one root node (Root), representing the IoT Gateway itself. Nodes in this library are derived from the MeteringNode class. All nodes deriving from MeteringNode inherit certain important properties: they are all persisted in the local object database.

They also maintain persisted information about their current state, and it is possible to log different types of messages on them:

Two specializations exist of the metering node: one that allows administrators to annotate it with metadata (MetaMeteringNode), and one that allows administrators to decide if its life cycle should be managed by a Thing Registry and provisioning server (ProvisioningMeteringNode).