Question: What's best practice to add data versioning?

Hi

I’m went through the latest CloudEvents docs and cannot find any examples on how to do the data versioning?

I saw the following example of EventGrid and see that there is eventTypeVersion in the header, but I think this based on CloudEvents V1.

• Is the SchemaUrl the right element to use?
• Do I need to add CloudEventExtension?
• Use GetAttributes() and just add it? (Smelly)

Or is there something, I didn’t saw?

Cédric

[jskeet]

I propose transferring this issue to the spec repo. It’s not really specific to the C# CloudEvents SDK, and it would benefit from views across the community.

@cmenzi is that okay with you?

[jskeet]

@cmenzi: That’s not quite the same though - because you don’t include the version in the type.

I envisage users subscribing to an event via just a type, and dataschema being effectively informational. If I subscribe to a particular event type, I don’t expect the schema to start changing on me in non-breaking ways. If it does, even if I can detect that via dataschema, I can’t do anything with it.

Instead, if the version is included within the type (e.g. com.mydomain.myservice.events.mymessagetype.v1) then an event producer that wants to create a breaking schema change can emit two events, one for v1 and one for v2, with different event types to distinguish them. Existing subscribers will receive the old schema, and new subscribers can choose to subscribe to v2. Eventually you’d want to turn off the v1 event type after an advertised deprecation period.