Package com.azure.core.util.polling

Interface PollingStrategy<T,U>

Type Parameters:
T - the TypeReference of the response type from a polling call, or BinaryData if raw response body should be kept
U - the TypeReference of the final result object to deserialize into, or BinaryData if raw response body should be kept
All Known Implementing Classes:
ChainedPollingStrategy, DefaultPollingStrategy, LocationPollingStrategy, OperationResourcePollingStrategy, StatusCheckPollingStrategy
public interface PollingStrategy<T,U>
Represents a known strategy for polling a long-running operation in Azure.

The methods in the polling strategy will be invoked from the PollerFlux. The order of the invocations is:

  1. canPoll(Response) - exits if returns false
  2. onInitialResponse(Response, PollingContext, TypeReference) - immediately after canPoll(Response) returns true
  3. poll(PollingContext, TypeReference) - invoked after each polling interval, if the last polling response indicates an "In Progress" status. Returns a PollResponse with the latest status
  4. getResult(PollingContext, TypeReference) - invoked when the last polling response indicates a "Successfully Completed" status. Returns the final result of the given type
If the user decides to cancel the AsyncPollResponse or SyncPoller, the cancel(PollingContext, PollResponse) method will be invoked. If the strategy doesn't support cancellation, an error will be returned.

Users are not expected to provide their own implementation of this interface. Built-in polling strategies in this library and other client libraries are often sufficient for handling polling in most long-running operations in Azure. When there are special scenarios, built-in polling strategies can be inherited and select methods can be overridden to accomplish the polling requirements, without writing an entire polling strategy from scratch.

  • Method Details

    • canPoll

      Mono<Boolean> canPoll(Response<?> initialResponse)
      Checks if this strategy is able to handle polling for this long-running operation based on the information in the initial response.
      Parameters:
      initialResponse - the response from the initial method call to activate the long-running operation
      Returns:
      true if this polling strategy can handle the initial response, false if not

    • onInitialResponse

      Mono<PollResponse<T>> onInitialResponse(Response<?> response, PollingContext<T> pollingContext, TypeReference<T> pollResponseType)
      Parses the initial response into a LongRunningOperationStatus, and stores information useful for polling in the PollingContext. If the result is anything other than LongRunningOperationStatus.IN_PROGRESS, the long-running operation will be terminated and none of the other methods will be invoked.
      Parameters:
      response - the response from the initial method call to activate the long-running operation
      pollingContext - the PollingContext for the current polling operation
      pollResponseType - the TypeReference of the response type from a polling call, or BinaryData if raw response body should be kept. This should match the generic parameter PollingStrategy.
      Returns:
      a publisher emitting the poll response containing the status and the response content

    • poll

      Mono<PollResponse<T>> poll(PollingContext<T> pollingContext, TypeReference<T> pollResponseType)
      Parses the response from the polling URL into a PollResponse, and stores information useful for further polling and final response in the PollingContext. The result must have the LongRunningOperationStatus specified, and the entire polling response content as a BinaryData.
      Parameters:
      pollingContext - the PollingContext for the current polling operation
      pollResponseType - the TypeReference of the response type from a polling call, or BinaryData if raw response body should be kept. This should match the generic parameter PollingStrategy.
      Returns:
      a publisher emitting the poll response containing the status and the response content

    • getResult

      Mono<U> getResult(PollingContext<T> pollingContext, TypeReference<U> resultType)
      Parses the response from the final GET call into the result type of the long-running operation.
      Parameters:
      pollingContext - the PollingContext for the current polling operation
      resultType - the TypeReference of the final result object to deserialize into, or BinaryData if raw response body should be kept.
      Returns:
      a publisher emitting the final result

    • cancel

      default Mono<T> cancel(PollingContext<T> pollingContext, PollResponse<T> initialResponse)
      Cancels the long-running operation if service supports cancellation. If service does not support cancellation then the implementer should return Mono.error with an error message indicating absence of cancellation. Implementing this method is optional - by default, cancellation will not be supported unless overridden.
      Parameters:
      pollingContext - the PollingContext for the current polling operation, or null if the polling has started in a SyncPoller
      initialResponse - the response from the initial operation
      Returns:
      a publisher emitting the cancellation response content