Facilitating the Co-Evolution of Semantic Descriptions in Standards and Models

One of the main activities of the Interfaces and Architecture (IFA) working group within the Network Function Virtualisation (NFV) Industry Specification Group (ISG) at the European Telecommunications Standards Institute (ETSI) is the specification of requirements and information modelling of NFV descriptors and artefacts. The information elements are spread across 11 different NFV-IFA specifications covering the scope of functionality of the individual functional blocks and reference points. Part of the work of the NFV-IFA working group is dedicated to producing a unified Information Model (IM) for NFV providing a consolidated view based on the different specifications. The IM has been helpful for the identification of gaps and inconsistencies in the specifications and in implementations of the specifications. With the growing size of the IM and the corresponding specifications and the rapid release cycles resulting from the intense work within the ISG, the IM plays an important role in helping to ensure that the specifications are consistent. Previous work outlined the foundations for facilitating the co-evolution of models and standards based on the NFV IM and models extracted from the related standardised specifications. It defined a methodology for consistency checking and alignment of the IM and the related specifications focusing on structural aspects. This article refines the methodology to address semantic descriptions as well as further aspects related to the co-evolution of standards and models. We also report on our experiences with the application of a prototypical implementation of the methodology during the continued alignment and maintenance of the information model and the related standardised specifications with the NFV-IFA working group and how the feedback from the working group provided insights on how to refine the methodology even further.