rs in order to drive The Network Operating System architectural consistency and operational efficiency. The logical representations of underlying ele- ments can be manipulated and extended by designers in consistent ways, and uniformly consumed by the runtime execution framework. Alignment between elements in the model space and those in the real world is continuously maintained through tooling that resolves dependencies, handles exceptions, and infers required actions based on the metadata associated with the modeled elements. One of the key benefits in a virtualized network architecture is a significantly decreased time from service concept to market deployment. The need to operationalize on a service-specific basis would be a major obstacle to this goal. Thus, network service operators have to manage their net- work cloud and on-demand services via the execution environment driven by a common (service independent) operations support model populated with service-specific metadata. In conjunction with this, these support systems will provide high levels of service management automation through the use of metadata-driven event-based control loops. Such an approach achieves another benefit of driving down support systems costs through the ability to support new services with changes only in the metadata, and without any code modifica- tions. In addition, a common operational support model across all offered services, coupled with high automation, drives down operations support costs (OpEx). ONAP implements a metadata- driven methodology in its network cloud by centralizing the creation of rules, analytic definitions, and policies in SDC. All ONAP applications and controllers will ingest the metadata that governs their behavior from SDC. Implementation of the metadata-driven methodology requires an enter- prise-wide paradigm change in the development process. It demands an upfront agreement on the overall metadata-model across the business (e.g., product development) and the software developers writing code for ONA