are made within the network cloud. It uses graph data technology to store relationships between inventory items. The graph traversals can then be used to identify chains of dependencies between items. A&AI data views are used by homing logic during real-time service delivery, root cause analysis of problems, impact analysis, capacity management, software license management, and many other required functions. The Network Operating System 3rd Party Clients ONAP Clients BSS/OSS Clients Gateway Platform API Handler Data Sources Network Cloud Platform Orchestrator Metadata Engine Inventory & Topology Management Entitlement Service Resource Active Available SDN Controller API Generation Reference Network Infrastructure Topology Assignment APP Controller Schema Generation Ordering Portal Graph Layer Version Management Entitlements & Metadata Inventory & Management Reference Topology BSS / OSS Management Functions History Event Notifications Data Audits Archival 3rd party cloud Subscriptions provider ONAP Platform & Common Services/APIs Data Movement Run-Time Catalog Event Mgmt. Logging Access Control Resiliency FIGURE 7.13 A&AI functional view in ONAP. The inventory and topology data includes resources, service, products, and customer subscrip- tions, along with topological relationships between them. Relationships captured by A&AI include "top to bottom" relationships such as those defined in SDC when products are composed of ser- vices, and services are composed of resources. It also includes "side to side" relationships such as end-to-end connectivity of virtualized functions to form service chains. A&AI also keeps track of the span of control of each controller, and is queried by MSO and placement functions to identify which controller to invoke to perform a given operation. A&AI is metadata driven, allowing new inventory item types to be added dynamically and quickly via SDC catalog definitions, reducing the need for lengthy development cycles. 7.8.1 KEY A&AI REQUIREMENTS The following list provides A&AI key requir