Lifecycle transitions

Intents can be requested through specific API endpoints on the orchestration Northbound API. This can be requested by a third-party system or it can be manually requested through the orchestration UI, which then calls the corresponding API.

Available API endpoints to request intents include:
  • adoptAssembly
  • changeAssemblyState
  • createAssembly
  • createOrUpgradeAssembly
  • deleteAssembly
  • healAssembly
  • scaleInAssembly
  • scaleOutAssembly
  • upgradeAssembly
The requests are forwarded to the intent engine of the orchestration component to resolve the actual execution path to reach the target state of the intent. With support from other components, like catalog and topology, intent engine resolves the necessary network service level actions, breaks them down to VNF and eventually to VNFC level lifecycle transitions, and figures out the correct order to execute the individual steps. The exact sequence of execution steps depends on the pattern of the network service, the current state of the service, and the requested target state of the service.
Figure 1. Interfaces relating to orchestration that participate in intent execution
This figure illustrates the interfaces that are related to orchestration that participate in intent execution.
In the following sections, a set of intent scenarios is illustrated using a sample network service (NS) illustrated in the following diagram. For the sake of clarity the network service used in the scenarios is selected to be very simplistic. The sample NS comprises of one VNF which contains one VNFC. The VNF is defined to be deployed as a cluster to allow scaling of the VNF.
Figure 2. Sample network service (NS).
Sample network service
  • API calls are not written out complete, but only the necessary parts to understand the intent are included.
  • Only successful scenarios are described.