io.nflow.engine.listener

Interface WorkflowExecutorListener

All Known Implementing Classes:

WorkflowLogContextListener

public interface WorkflowExecutorListener

WorkflowExecutorListener is a global, stateless listener for workflow executors. The interface contains default (no-op) method implementations.

Same instance of WorkflowExecutorListener is used for all workflow state executions: all state must be stored in ListenerContext.data.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	WorkflowExecutorListener.ListenerContext ListenerContext instance is created at start of workflow state execution and passed to listener's life-cycle methods.

Method Summary

Modifier and Type	Method and Description
default void	afterFailure(WorkflowExecutorListener.ListenerContext listenerContext, Throwable throwable) Executed after state processing has failed and before persisting state.
default void	afterProcessing(WorkflowExecutorListener.ListenerContext listenerContext) Executed after state has been successfully processed and before persisting state.
default void	beforeProcessing(WorkflowExecutorListener.ListenerContext listenerContext) Executed before state is processed.
default boolean	handlePotentiallyStuck(WorkflowExecutorListener.ListenerContext listenerContext, org.joda.time.Duration processingTime) Called when instance processing is potentially stuck.
default NextAction	process(WorkflowExecutorListener.ListenerContext listenerContext, ListenerChain chain) Processing chain.

Method Detail

beforeProcessing

default void beforeProcessing(WorkflowExecutorListener.ListenerContext listenerContext)

Executed before state is processed. Exceptions are logged but they do not affect workflow processing.

Parameters:

listenerContext - The listener context.

process

default NextAction process(WorkflowExecutorListener.ListenerContext listenerContext,
                           ListenerChain chain)

Processing chain. Process methods in listeners form a Chain of Responsibility pattern. Listener can either call chain.next(listenerContext) to proceed to next filter or not to call it causing processing of state to be skipped. Changes to workflowInstance (not child workflows or state variables) by the filter will be persisted to database.

Typical implementation:

public NextAction process(ListenerContext listenerContext, ListenerChain chain) { return chain.next(listenerContext); }

Parameters:

listenerContext - The listener context.

chain - The listener chain.

Returns:

NextAction

afterProcessing

default void afterProcessing(WorkflowExecutorListener.ListenerContext listenerContext)

Executed after state has been successfully processed and before persisting state. Exceptions are logged but they do not affect workflow processing.

Parameters:

listenerContext - The listener context.

afterFailure

default void afterFailure(WorkflowExecutorListener.ListenerContext listenerContext,
                          Throwable throwable)

Executed after state processing has failed and before persisting state. Exceptions are logged but they do not affect workflow processing.

Parameters:

listenerContext - The listener context.

throwable - The exception thrown by the state handler method.

handlePotentiallyStuck

default boolean handlePotentiallyStuck(WorkflowExecutorListener.ListenerContext listenerContext,
                                       org.joda.time.Duration processingTime)

Called when instance processing is potentially stuck. Return true to interrupt the processing thread. Default implementation returns false.

Parameters:

listenerContext - The listener context.

processingTime - How long the instances has been processed.

Returns:

True if processing should be interruped, false otherwise.