Get schemaurl of an existing definition

Is there is a way to get the schemaurl associated with an existing definition that was not deployed using the manager? It was created with the older idx tools (createdefinition and publishschema). I have the definition ID (kjzl6cwe1jw…)

If you use the ModelManager, you can simply import the definition using the useDeployedDefinition() method and it will also import the schema.
Otherwise, you can simply load the definition stream based on its ID and check the schema value in the stream contents.