## 3 Smart5 Grid Platform
### V&V Framework  
The _V&V framework_ is split into two sub-modules, the verification and the validation engines. The _verification engine_ assesses the syntax, integrity, and topology of the Net Apps and/or VNFs. The _validation engine_ addresses the information model translation (IMT) module, the onboarding and instantiation in a particular M&O framework, and the key performance indicator (KPI) retrieval and validation. The IMT module was designed in a plugin-based approach to suit future needs of adding the support of more information models and, thus, assuring the growing compatibility of more M&O frameworks.  
The verification component of the V&V framework addresses the composition of the Smart5 Grid NetApp descriptors. It provides verification on the following elements.  
_Syntax verification_: The NetApp descriptor and corresponding virtual network function descriptors (VNFDs) are syntactically validated against the scheme templates specified by the data model of Smart5 Grid.  
_Integrity verification_: The validation of integrity verifies the overall structure of descriptors through the inspection of references and identifiers both within and outside the individual descriptors. As NetApp and VNFDs have different information scopes, the validation goals of this type of activity either in the context of a VNF or NetApp validation are provided as follows:NetApp integrity: NetApp descriptors typically contain references to multiple VNFs, which are identified by the VNFD. The integrity validation ensures that the references are valid by checking the existence of the targeted VNFs. Integrity validation also verifies the connection points (CPs) of the NetApp. This comprises the virtual interfaces of the NetApp itself and the interfaces linked to the referenced VNFs.  
VNF integrity: The integrity validation of a VNF follows a similar procedure of a NetApp integrity validation, with the difference of virtual digital units (VDUs) being defined inside the VNFD itself.  
_Topology verification:_ This provides a set of mechanisms to validate the network connectivity graph to aid the development of connectivity logic. Typically, a NetApp contains several inter-connected VNFs, and each VNF may also contain several inter-connected VDUs. The connection topology between VNFs and VDUs (within VNFs) must be analyzed to ensure a correct connectivity topology.  
The validation process comprises the deployment and instantiation of the NetApp to be validated by the M&O framework. In Smart5 Grid, the V&V platform is expected to have the associated M&O framework to perform the NetApp validation tests, which can be of multiple types as well.  
NetApp onboarding: Once the translation process is finished, the next logical step is to onboard the NetApp in the corresponding M&O framework.  
NetApp instantiation: At this step, the validation engine will request the instantiation of the NetApp.  
Retrieve KPIs: To properly validate the NetApp, the validation engine will ensure that certain specified KPIs are met. Hence, the M&O framework will have a mechanism to measure and provide such metrics.  
Validation results analysis: This process verifies if the retrieved KPIs are within the thresholds specified by the developer. It is this process that determines if a NetApp is successfully validated.