Termination of NetConf Sessions

OAM interface specification

The figure below shows the generic principals of reading and writing operations via TLS/NetConf/Yang for configuration management. 

Subject of this discussion is about implementing a mechanisme, which ensures that the NetConf session is closed after NetConf operations.

Typical NetConf client behavior

Usually NetConf clients do not terminate the NetConf session automatically. With respect to ONAP-CCSDK/OpenDaylight; once ODL is aware of a NetConf server by creating a mountpoint in odl-netconf-topology, it has an automated mechanism trying to connect that NetConf server. In case the NetConf session is lost, it automatically will re-connect. 

Such mechanism needs to be "disabled" and the NetConf Session termination request must be implemented.

Proposed solution

Add an optional attribute called 'permanet-connection' to the netconf-node-topology.yang to grouping 'netconf-node-connection-parameters' with type BOOLEAN and default value TRUE. 

This way applications controlling the NetConf connection can distinguish between the currently existing behavior and the new O1-interface-behavior. Old implementations are not affected, because the new attribute is optional and its default value is according to the current behavior. 

Proposed modification on network-node-topology.yang:

 ...
 149         }
 new
 new         leaf permanent-connection {
 new             config true;
 new             type boolean;
 new             default true;
 new             description "If false, the connector disconnects, by sending <close-session> 
                              after a transaction is completed - usually after the response 
							  of <unlock>." 
 new         }
 150 
 151         leaf connection-timeout-millis {
 152             description "Specifies timeout in milliseconds after which connection must be established.";
 ...