Upgrading network service

When an Upgrade transition is requested, the root assembly descriptor and its properties are changed. These changes cascade through the assembly hierarchy and might change the descriptors and properties of the assembly's resources. Resources can't be changed after they reach the Installed lifecycle state. Therefore, if the affected resources cannot be modified, then they are removed and re-created.

Resources that include the Upgrade transition can be modified through this transition without changes to any state transitions. The Upgrade transition can be completed only on resources that are in the Active state.

The purpose of an upgrade is to change the pattern of a service instance while keeping the identity of the service instance the same. The change can be made on different levels on the service hierarchy: NS, VNF, or VNFC.

The intended target pattern of the service is specified in a new version of the service descriptor that is provided as input to the upgrade request. The upgrade sequence affects only the necessary parts of the service, according to the scope of required change. The impacted parts of the service are first deleted and subsequently re-created according to the new version of the descriptor.