As the Corda platform evolves and new features are added it becomes important to have a versioning system which allows its users to easily compare versions and know what features are available to them. Each Corda release uses the standard semantic versioning scheme of major.minor.patch. This is useful when making releases in the public domain but is not friendly for a developer working on the platform. It first has to be parsed and then they have three separate segments on which to determine API differences. The release version is still useful and every MQ message the node sends attaches it to the release-version header property for debugging purposes.

It is much easier to use a single incrementing integer value to represent the API version of the Corda platform, which is called the Platform Version. It is similar to Android’s API Level. It starts at 1 and will increment by exactly 1 for each release which changes any of the publicly exposed APIs in the entire platform. This includes public APIs on the node itself, the RPC system, messaging, serialisation, etc. API backwards compatibility will always be maintained, with the use of deprecation to migrate away from old APIs. In rare situations APIs may have to be removed, for example due to security issues. There is no relationship between the Platform Version and the release version - a change in the major, minor or patch values may or may not increase the Platform Version.

The Platform Version is part of the node’s NodeInfo object, which is available from the ServiceHub. This enables a CorDapp to find out which version it’s running on and determine whether a desired feature is available. When a node registers with the Network Map Service it will use the node’s Platform Version to enforce a minimum version requirement for the network.