waku-rest-api/api-spec/relayapi_messages.yaml

# /relay/v1/messages/{pubsubTopic}:  # Note the plural in messages
get: # get_waku_v2_relay_v1_messages
  summary: Get the latest messages on the polled topic
  description: Get a list of messages that were received on a subscribed PubSub topic after the last time this method was called. By default, messages are selected from the last 30 messages received by the node. You can modify the number of cached messages with the --rest-relay-cache-capacity CLI argument.
  operationId: getMessagesByTopic
  tags:
    - relay
  parameters:
    - in: path
      name: pubsubTopic   # Note the name is the same as in the path
      required: true
      schema:
        type: string
      description: The user ID
  responses:
    '200':
      description: The latest messages on the polled topic.
      content:
        application/json:
          schema:
            $ref: './schemas/apitypes.yaml#/RelayGetMessagesResponse'
    '4XX':
      description: Bad request.
    '5XX':
      description: Unexpected error.

post: # post_waku_v2_relay_v1_message
  summary: Publish a message to be relayed
  description: Publishes a message to be relayed on a PubSub topic.
  operationId: postMessagesToTopic
  tags:
    - relay
  parameters:
    - in: path
      name: pubsubTopic   # Note the name is the same as in the path
      description: The messages content topic
      required: true
      schema:
        $ref: './schemas/apitypes.yaml#/RelayPostMessagesRequest'
  requestBody:
    content:
      application/json:
        schema:
          $ref: './schemas/apitypes.yaml#/RelayPostMessagesRequest'
  responses:
    '200':
      description: OK
    '4XX':
      description: Bad request.
    '5XX':
      description: Unexpected error.