Method and system for processing write queries in an application programming interface based on declarative schemas for individual services

Certain aspects of the present disclosure provide techniques for processing north-south queries in an application programming interface (API) generated for a plurality of associated services. The method generally includes receiving a request to invoke a function exposed by a first service in the API, wherein the function commits data to one or more data repositories. A data record is generated by the first service based on the received request based on a data object definition and a service definition for the first service. A message is generated including the generated data record and an indication that the message is to be consumed by a data lake processing system to commit data to a data lake. The message is published on a message bus for consumption by the data lake processing system.