Polling

Polling instructs the client to periodically make an HTTP GET request to the specified URL and eventually trigger an action.

Polling is typically used alongside External. For example, a step may first open an external URL and then poll for a server state change. The client may continue to another step or end the flow.

Given the step below, the client will start making requests to the specified URL every 5 seconds.

To continue polling, the response should have a 2xx status code and an empty body. The client will continue to make requests until the flow progresses or [maxAttempts] is reached.

To stop polling, the response should be a Flow Response with the X-DF-Response-Type header set accordingly. Note that older clients only support Action Response Body

Step.build {
    layout { }
    polling {
        url = "https://bar.foo/status?id=12345"
        delay = 5
        timeout = 60
        maxAttempts = 100
        onError {
            behavior = ActionBehavior.build {
                action {
                    exit = true
                    result = encodeToJsonElement(mapOf("exit-action-data" to "EXIT!!!"))
                }
            }
        }
    }
}

Given the above step, the behaviour in the onError object is triggered if:

• the response status code is a failure (>=400).
• the number of attempts exceeds the specified maxAttempts
• the response body does not match the X-DF-Response-Type header provided