Interface Flow<StartInput>

Type Parameters:
StartInput - the Java input type accepted by the Flow's start Step
public interface Flow<StartInput>
Defines the Steps, persistence, and RPC surface of one Flow type.

Applications implement this interface on a concrete class and register an instance with Registry. The generic parameter is the input accepted by the start Step; the typed StepList.startStep(Step) factory enforces that relationship at compile time. A Flow may omit a start Step and begin only through an RPC. The default Flow type is the concrete class's simple name, so explicit named classes make that type predictable and reviewable. 

final class OrderFlow implements Flow<OrderInput> {
    private final ValidateOrder start = new ValidateOrder();
    private final ChargeOrder charge = new ChargeOrder();

    @Override
    public StepList<OrderInput> getSteps() {
        return StepList.startStep(start).otherSteps(charge);
    }
}

  • Method Details

    • getFlowType

      default String getFlowType()
      Returns the Flow type used to register and start this Flow.

      The default is getClass().getSimpleName(). Override it when refactoring the Java class name must not change the Flow type stored by Dex.

      Returns:
      the nonblank Flow type

    • getSteps

      default StepList<StartInput> getSteps()
      Returns the Flow's start Step and all other registered Steps.

      The default is an empty list, which is valid for an RPC-only Flow. Every Step targeted by a decision or RPC result must appear in this list.

      Returns:
      the immutable typed Step list; never null

    • getPersistenceSchema

      default PersistenceSchema getPersistenceSchema()
      Returns the persistent Attributes and Channels used by this Flow.

      The default schema is empty. Every persistence definition used by Steps or RPC methods must be registered here.

      Returns:
      the Flow's immutable persistence schema; never null

    • handleTimeout

      default StepDecision handleTimeout(Context context)
      Handles expiration of this Flow's soft timeout.

      Override this method to make a positive timeout default to FlowTimeoutPolicy.HANDLER. Dex starts one logical execution after the durable timeout timer completes or is skipped; configured retry attempts may invoke it more than once. The returned decision may transition to another Step, end without closing, complete, fail, or request graceful completion. The Context belongs to this invocation and must not be retained.

      Parameters:
      context - the timeout-handler invocation Context
      Returns:
      the non-null decision applied with normal Step Execute semantics
      Throws:
      UnsupportedOperationException - when called without an application override