Page 136 - ITU-T Focus Group IMT-2020 Deliverables

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In summary, SONATA's main contribution to 5G Networking is efficient integration of service
programmability, domain orchestration functionality and DevOps functionality. This will maximize the
predictability, efficiency, security, and maintainability of development and operational processes around
virtualized network functions and chain services

6.4.4.3 5G SONATA architecture

The high-level service deployment procedure is illustrated in the service platform. Each VIM/WIM provides
the controlling service platform a view of the available resources and capabilities of its underlying
infrastructure/network. A gatekeeper module in the service platform is responsible for processing the
incoming requests. The service platform receives the service packages implemented and created with the
help of SONATA's SDK and is responsible for placing, deploying, provisioning, scaling, and managing the
services on existing cloud infrastructures. For this purpose, it has modules for orchestrating and managing
the complete service chain, as well as managing on the VNF level. All artefacts needed to deploy the service
can be fetched from catalogues and repositories. The platform can also provide direct feedback about the
deployed services to the SDK, for example, monitoring data about a service or its components. SONATA's
service platform is designed with full customization possibility, providing flexibility and control to both
operators and developers. The core mechanism for this is a microservices-based plug-in architecture (Figure
6.4.4-2): all functionality that is to be provided by an orchestrator is assigned to specific plug-ins, all of which
are connected to a message bus that ensures correct delivery semantics of all control messages between
these plug-ins. Some of these plug-ins implement exactly one function per orchestrator (e.g., the conflict
resolver plug-in, which ensures that any possible resource conflicts between services are resolved in a
consistent, service-neutral fashion).
Other plug-ins can be customized by the deployed service itself with caretaking code: these plugins then act
as an executive (akin to Microsoft Window’s operating system concept) for this service-specific code.
The service developer can ship the service package to the service platform together with service- or function-
specific caretaking code, expressing and realizing requirements and preferences. Such caretaking code is
referred to in SONATA as Service-Specific Managers (SSM) and Function-Specific Managers (FSM),
respectively. SSMs and FSMs can influence the Service and VNF lifecycle management operations, e.g., by
specifying desired placement or scaling behaviour. This grants the developer increased flexibility, control and
resilience of their service.

Figure 6.4.4-2 – Main plugins into SONATA’s architecture transport network architecture

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