com.cookingfox.lapasse.impl.command.bus

Class DefaultCommandBus<S extends State>

java.lang.Object

com.cookingfox.lapasse.impl.message.bus.AbstractMessageBus<Command,CommandHandler<S,Command,Event>>

com.cookingfox.lapasse.impl.command.bus.DefaultCommandBus<S>

Type Parameters:

S - The concrete type of the state object.

All Implemented Interfaces:

CommandBus<S>, CommandLoggerAware, Disposable, MessageBus<Command,CommandHandler<S,Command,Event>>

public class DefaultCommandBus<S extends State>
extends AbstractMessageBus<Command,CommandHandler<S,Command,Event>>
implements CommandBus<S>

Default implementation of CommandBus.

Field Summary

Fields

Modifier and Type	Field and Description
protected ExecutorService	commandHandlerExecutor Executor service that runs the async command handlers.
protected EventBus<S>	eventBus The event bus to pass generated events to.
protected CommandLoggerHelper	loggerHelper Used for logging the command handler operations.
protected StateObserver<S>	stateObserver Provides access to the current state.
protected static Set<Class<? extends CommandHandler>>	SUPPORTED Set of supported command handlers.

Fields inherited from class com.cookingfox.lapasse.impl.message.bus.AbstractMessageBus

messageHandlerMap, messageStore, onMessageAddedToStore

Constructor Summary

Constructors

Constructor and Description
DefaultCommandBus(MessageStore messageStore, EventBus<S> eventBus, CommandLoggerHelper loggerHelper, StateObserver<S> stateObserver)

Method Summary

Modifier and Type	Method and Description
void	addCommandLogger(CommandLogger logger) Add a command logger.
void	dispose() Hook for cleaning up: remove listeners, shutdown threads, etc.
protected void	executeCommandHandler(S state, Command command, CommandHandler<S,Command,Event> handler) Execute a command handler that produces 0 or 1 event.
protected void	executeHandler(Command command, CommandHandler<S,Command,Event> commandHandler) Actually execute the message handler for this message.
protected void	executeMultiCommandHandler(S state, Command command, MultiCommandHandler<S,Command,Event> handler) Execute a command handler that produces a collection of events.
protected ExecutorService	getCommandHandlerExecutor() Returns the command handler executor.
void	handleCommand(Command command) Execute the command handler that is mapped to this command type.
protected void	handleMultiResult(Throwable error, Command command, Collection<Event> events) Handle result from a 'multi' command handler.
protected void	handleResult(Throwable error, Command command, Event event) Handle result from a 'single' command handler.
protected <C extends Command,E extends Event> void	isCommandHandlerSupported(CommandHandler<S,C,E> commandHandler) Checks whether this command handler implementation is supported.
<C extends Command,E extends Event> void	mapCommandHandler(Class<C> commandClass, CommandHandler<S,C,E> commandHandler) Map a command handler for a concrete command type.
void	removeCommandLogger(CommandLogger logger) Remove a command logger.
void	setCommandHandlerExecutor(ExecutorService executor) Sets the executor service to use for executing async command handlers.
protected boolean	shouldHandleMessageType(Message message) Returns whether this message bus implementation should handle the concrete message object.

Methods inherited from class com.cookingfox.lapasse.impl.message.bus.AbstractMessageBus

getMessageHandlers, handleMessage, mapMessageHandler

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SUPPORTED

protected static final Set<Class<? extends CommandHandler>> SUPPORTED

Set of supported command handlers.

commandHandlerExecutor

protected ExecutorService commandHandlerExecutor

Executor service that runs the async command handlers.

eventBus

protected final EventBus<S extends State> eventBus

The event bus to pass generated events to.

loggerHelper

protected final CommandLoggerHelper loggerHelper

Used for logging the command handler operations.

stateObserver

protected final StateObserver<S extends State> stateObserver

Provides access to the current state.

Constructor Detail

DefaultCommandBus

public DefaultCommandBus(MessageStore messageStore,
                         EventBus<S> eventBus,
                         CommandLoggerHelper loggerHelper,
                         StateObserver<S> stateObserver)

Method Detail

addCommandLogger

public void addCommandLogger(CommandLogger logger)

Description copied from interface: CommandLoggerAware

Add a command logger.

Specified by:

addCommandLogger in interface CommandLoggerAware

Parameters:

logger - The command logger to add.

dispose

public void dispose()

Description copied from interface: Disposable

Hook for cleaning up: remove listeners, shutdown threads, etc.

Specified by:

dispose in interface Disposable

Overrides:

dispose in class AbstractMessageBus<Command,CommandHandler<S extends State,Command,Event>>

handleCommand

public void handleCommand(Command command)

Description copied from interface: CommandBus

Execute the command handler that is mapped to this command type. Throws if no handler is mapped yet.

Specified by:

handleCommand in interface CommandBus<S extends State>

Parameters:

command - The command to handle.

See Also:

CommandBus.mapCommandHandler(Class, CommandHandler)

mapCommandHandler

public <C extends Command,E extends Event> void mapCommandHandler(Class<C> commandClass,
                                                                  CommandHandler<S,C,E> commandHandler)

Description copied from interface: CommandBus

Map a command handler for a concrete command type.

Specified by:

mapCommandHandler in interface CommandBus<S extends State>

Type Parameters:

C - The concrete command type that this handler will handle.

E - The concrete event type that this handler will produce.

Parameters:

commandClass - The concrete command type that this handler will handle.

commandHandler - The handler that is executed when CommandBus.handleCommand(Command) is called.

removeCommandLogger

public void removeCommandLogger(CommandLogger logger)

Description copied from interface: CommandLoggerAware

Remove a command logger.

Specified by:

removeCommandLogger in interface CommandLoggerAware

Parameters:

logger - The command logger to remove.

setCommandHandlerExecutor

public void setCommandHandlerExecutor(ExecutorService executor)

Sets the executor service to use for executing async command handlers.

Specified by:

setCommandHandlerExecutor in interface CommandBus<S extends State>

Parameters:

executor - The executor service to use.

executeHandler

protected void executeHandler(Command command,
                              CommandHandler<S,Command,Event> commandHandler)

Description copied from class: AbstractMessageBus

Actually execute the message handler for this message.

Specified by:

executeHandler in class AbstractMessageBus<Command,CommandHandler<S extends State,Command,Event>>

Parameters:

command - The message to handle.

commandHandler - The message handler that is associated with this message.

shouldHandleMessageType

protected boolean shouldHandleMessageType(Message message)

Description copied from class: AbstractMessageBus

Returns whether this message bus implementation should handle the concrete message object. Typically this returns the result of an `instanceof` check for the concrete message type `M`.

Specified by:

shouldHandleMessageType in class AbstractMessageBus<Command,CommandHandler<S extends State,Command,Event>>

Parameters:

message - The concrete message object.

Returns:

Whether the message should be handled by this message bus.

See Also:

M

executeCommandHandler

protected void executeCommandHandler(S state,
                                     Command command,
                                     CommandHandler<S,Command,Event> handler)

Execute a command handler that produces 0 or 1 event.

Parameters:

state - The current state object.

command - The command object.

handler - The handler to execute.

executeMultiCommandHandler

protected void executeMultiCommandHandler(S state,
                                          Command command,
                                          MultiCommandHandler<S,Command,Event> handler)

Execute a command handler that produces a collection of events.

Parameters:

state - The current state object.

command - The command object.

handler - The handler to execute.

getCommandHandlerExecutor

protected ExecutorService getCommandHandlerExecutor()

Returns the command handler executor. Creates a new single thread executor if it has not been set explicitly.

Returns:

The command handler executor.

handleResult

protected void handleResult(Throwable error,
                            Command command,
                            Event event)

Handle result from a 'single' command handler.

Parameters:

error - (Optional) An error that occurred.

command - The command that was handled.

event - (Optional) The event that was produced by the command handler.

handleMultiResult

protected void handleMultiResult(Throwable error,
                                 Command command,
                                 Collection<Event> events)

Handle result from a 'multi' command handler.

Parameters:

error - (Optional) An error that occurred.

command - The command that was handled.

events - (Optional) The events that were produced by the command handler.

isCommandHandlerSupported

protected <C extends Command,E extends Event> void isCommandHandlerSupported(CommandHandler<S,C,E> commandHandler)

Checks whether this command handler implementation is supported.

Type Parameters:

C - Concrete type of the command.

E - Concrete type of the event.

Parameters:

commandHandler - The command handler to check.

Throws:

UnsupportedCommandHandlerException - if the implementation is not supported.