When you create, update, or delete a stack that contains a custom resource, Resource Orchestration Service (ROS) specifies the operation in the RequestType field of the request object sent to the provider.
Each request type includes a specific set of fields, along with a response URL (ResponseURL or InnerResponseURL) from the custom resource provider. The provider must respond with a SUCCESS or FAILED result within the timeout period (1 to 43,200 seconds). If the provider does not respond in time, the request times out. Each result also includes a specific set of fields required by ROS.
ROS provides the following request types: