Interface Step<I>

Type Parameters:

I - the concrete Java input type accepted by this Step

public interface Step<I>

Implements one durable unit of Flow logic.

waitFor(Context, I) is optional. When a Step does not override it, Dex skips the waiting phase and invokes execute(Context, I) immediately. When a Step implements waitFor, Dex invokes execute after the declared durable conditions are satisfied. Both methods are synchronous Java calls executed by the worker's bounded executor. A Step instance is shared across invocations, so keep per-execution state in Context, Attributes, or method-local variables rather than mutable instance fields.

final class ChargeOrder implements Step<OrderInput> {
    @Override
    public Class<OrderInput> getInputType() {
        return OrderInput.class;
    }

    @Override
    public Wait waitFor(Context context, OrderInput input) {
        return Wait.until(payment.forOne());
    }

    @Override
    public StepDecision execute(Context context, OrderInput input) {
        return StepDecision.gracefulComplete(input.orderId);
    }
}

Method Summary

Modifier and Type	Method	Description
StepDecision	execute(Context context, I input)	Executes the Step's application logic and returns its durable decision.
Class<I>	getInputType()	Returns the concrete class used to decode this Step's input.
default StepOptions	getStepOptions()	Returns retry, timeout, durability, locking, and failure behavior for this Step.
default String	getStepType()	Returns the Step type used to register this Step.
default Wait	waitFor(Context context, I input)	Declares the conditions that must be satisfied before execution.

Method Details

getInputType

Class<I> getInputType()

Returns the concrete class used to decode this Step's input.

The class must agree with I. A parameterized input such as List<Order> cannot be returned because List.class does not retain its element type. Wrap the list in a concrete input class and return that wrapper's class, or use Order[].class when an array fits the input model.

Returns:

the concrete, nonnull Step input class

execute

StepDecision execute(Context context,
 I input)

Executes the Step's application logic and returns its durable decision.

Parameters:

context - the invocation-scoped Flow context

input - the decoded Step input, which may be null for Void Steps

Returns:

the nonnull decision describing the next durable action

waitFor

default Wait waitFor(Context context,
 I input)

Declares the conditions that must be satisfied before execution.

When this method is not overridden, the registry marks the Step to skip wait-for invocation and execute immediately. An override may also return Wait.skipImmediately() explicitly.

Parameters:

context - the invocation-scoped Flow context

input - the decoded Step input

Returns:

the nonnull durable wait definition

getStepType

default String getStepType()

Returns the Step type used to register this Step.

The default is getClass().getSimpleName(). Use an explicit named class or override this method so refactoring does not accidentally change the Step type stored by Dex.

Returns:

the nonblank Step type

getStepOptions

default StepOptions getStepOptions()

Returns retry, timeout, durability, locking, and failure behavior for this Step.

Returns:

Step-specific options, or null to use all defaults