Glossary

Primary Resource - the resource that represents the desired state that the controller is working to achieve. While this is often a Custom Resource, it can be also be a Kubernetes native resource (Deployment, ConfigMap,…).
Secondary Resource - any resource that the controller needs to manage the reach the desired state represented by the primary resource. These resources can be created, updated, deleted or simply read depending on the use case. For example, the Deployment controller manages ReplicaSet instances when trying to realize the state represented by the Deployment. In this scenario, the Deployment is the primary resource while ReplicaSet is one of the secondary resources managed by the Deployment controller.
Dependent Resource - a feature of JOSDK, to make it easier to manage secondary resources. A dependent resource represents a secondary resource with related reconciliation logic.
Low-level API - refers to the SDK APIs that don’t use any of features (such as Dependent Resources or Workflows) outside of the core
Reconciler interface. See the WebPage sample . The same logic is also implemented using Dependent Resource and Workflows