Approaches to integrate Service Registry and 3scale as part of the API Lifecycle

Service Registry is a standalone schema and API spec catalog, that is part of the Red Hat Integration suite of products. Service Registry is an important piece of the API Lifecycle for Schema Governance, Discovery and Versioning across the Organisation, for both APIs and Events. Service Registry is being released as a Managed Service, and along with RHOAM will form a part of the Managed API Management offering. Thus, it is necessary to provide better integration between 3scale and Service Registry for API Management.

In order to address this, the following 2 stages of Integration are proposed:

Stage 1 : CLI Based Integration

1. Importing OAS to create backend APIs: 
   1. Importing APIs as backends instead of products. THREESCALE-7715
   2. Ability to add multiple backends to a product, and define public URL for product. ongoing conversation on what the exact behaviour should be in 
   3. Storing OAS in 3scale (at backend level)
   4. building Product level OAS from multiple backend OAS's
2. Versioning: needs more investigation as OAS doesn't allow for API version inside OAS (version in the OpenAPI document refers to the version of the document not the version of the API.
   1. Importing minor version update to same endpoint updates the existing backend.
   2. Importing major version update creates new backend.
   3. On importing new versions of a backend, update product level OAS's in 3scale.

Stage 2: Discovery Wizard in 3scale Admin Portal

Provide a similar functionality as the toolbox import API command to provide URL to the OAS spec and import as backend. 

Also provide UI to merge Open API specs for backends to create the Product OAS.