Produce Protobuf message using Rest proxy API

I am exploring options to integrate an ITSM system with Kafka. This needs Protobuf messages sent to Kafka via rest proxy API.

I followed below two articles and set the request body and headers.

https://docs.confluent.io/platform/current/kafka-rest/quickstart.html#produce-and-consume-protobuf-messages

On Confluent, I have created a topic and a schema for testing. Though I am able to produce a message under the topic via JSON, I am not able to produce Protobuf messages.

  1. I am not even able to test the ‘GET’ method as I am not able to find the SchemaRegistryHost and port. How can get these details from the Confluent console?
    http://{SchemaRegistryHost}:{SchemaRegistryPort}/subjects/salesorder_topic-value/versions/1

  2. Though I took the Schema ID manually and supplied it in the input, I received the message “{“error_code”:405,“message”:“HTTP 405 Method Not Allowed”}”. This made me think if there is any action needed on Schema for the ‘POST’ method to work.

  3. Aside, as this is not JSON, I wonder if I could not test this out in Postman. If it’s possible how can I test it otherwise what other tools can help me to perform the test?