When a template developer creates, updates, or deletes a stack that contains a custom resource, the request type is specified in the RequestType field of the provider request object sent by Resource Orchestration Service (ROS).
Each request type has a particular set of fields that are sent with the request, including a response URL (ResponseURL or InnerResponseURL) provided by the custom resource provider. The provider must respond to the URL with a SUCCESS or FAILED result within the timeout period (1 to 43,200 seconds). After the timeout period, the request times out. Each result also has a particular set of fields required by ROS.
ROS provides the following request types: