I can't seem to find clear in the docs what are the advantages of using AvroKafkaSerializer (that have schema support) vs serializing the object "manually" in code and sending them as bytes/string ?
Maybe schema check when producing a new message? What are the others ?
A message schema is a contract between a group of client applications producing and consuming messages. Schema validation is required when you have many independent applications that need to agree on a specific format, in order to exchange messages reliably.
If you also add a Schema Registry into the picture, then you don't need to include the schema in all your services or every single message, but you will get it from the common registry, with the additional support of schema evolution and validation rules (i.e. backward compatibility, versioning, syntax validation). It is one of the fundamental components in event driven architectures (EDA).