Subjects | OpenMeter

Subjects in OpenMeter are entities that consume metered resources. A subject can range from users, servers, and services to devices. The design of subjects is intentionally generic, enabling flexible application across various metering scenarios. Typically, a subject acts as a unique identifier within your system for a user or customer.

Example subjects include:

Customer ID or User ID
Hostname or IP address
Service or Application name
Device ID

#Why Subject?

The concept of subjects is carried over from the CloudEvents specification, that OpenMeter uses for data ingestion:

{
  "specversion": "1.0",
  "type": "api-calls",
  "id": "00001",
  "time": "2025-01-01T00:00:00.001Z",
  "source": "my-service",
  "subject": "my-user-id-1",
  "data": {...}
}

We choose subjects as they are generic. This allows OpenMeter to be flexible and applicable across various metering scenarios.

For example some OpenMeter users will choose subjects to represent users, organizations and companies others will choose subjects to represent, devices or services.