As you are using it with Kafka, https://github.com/gklijs/bkes-demo/blob/main/graphql-endpoint/src/nl/openweb/graphql_endpoint/transaction_service.clj might help as example.

Internally, Lacinia uses core.async to model the asynchronous behavior associated with streams.

However, it doesn't expose that directly, instead it provides a function, a source stream, that your code may repeatedly invoke.

That function puts values into the necessary core.async channels, and ultimately, ensures that the data is pushed down to the client.

okay, thank you @U26FJ5FDM @U04VDKC4G

If we have it (source-stream (sum a b)) then we should run the subscription as {subscription (a:1, b:2) {ask anything to return}}

Yes, something like that. But it's an subscription, so you need something in place that when whatever happens that should result in a new message, you call the source-stream function again.

okay, thanks @U26FJ5FDM