The S3 – Service Interfaces viewpoint of NAF v4 enables you to model the structure of your service architecture – including ServiceSpecifications and the ServiceInterfaces they expose or use. Specifying the interface for the service provides a means of determining compatibility between service consumers and providers. You can also show the composition of services and how services are combined into a higher level service required to exhibit a capability or support an operational activity.

If you place a Service Interface symbol inside a ServiceSpecification symbol, the ServiceInterface is added to the definition of the ServiceSpecification in its list of Service Interfaces (Ports) on its Interfaces tab.

You connect ServiceInterfaces with the Service Connector relationship; you may also connect ServiceSpecifications directly with the Service Connector relationship line.