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As is common with web APIs, over time changes will be made to support new use cases and deprecate old ways of working. The NMOS APIs are no different, and have been designed to permit in-service upgrades across a facility which may be running large amounts of equipment with support for different versions of these specifications.
API versioning is specified in the APIs documentation, with procedures for handling upgrades described below.
Requirements for Connection Management APIs
Implementers of the Connection Management API must support at least one API version, and may support more than one at a time.
Where a transport type is added in a new version of the Connection Management API specification, earlier versioned APIs must not list any Senders or Receivers which make use of this new transport type. In these cases, requests to an inaccessible ID MUST return a 409 HTTP code.
Where new transport parameters are added to a pre-existing transport type in a new version of the Connection Management API, earlier versioned APIs must not list these parameters. New transport parameters should be defined such that a request which omits them can proceed without error. This ensures that servers implementing multiple versions of the Connection Management API can continue to process earlier versioned requests successfully.
Connection Management APIs are not required to provide for forwards compatibility as it may be impossible to generate data for new attributes in schemas.
Requirements for Connection Management clients
Implementers of Connection Management clients are strongly recommended to support multiple versions of the Connection Management API simultaneously in order to ease the upgrade process in live facilities.
The following procedure is suggested for a live system which needs to migrate between API versions.
- Upgrade API clients to their new versions, which must support all Connection Management API versions you are currently using in your deployment.
- Upgrade Connection Management API implementations to support the new API version.