org.axonframework.commandhandling

Class SimpleCommandBus

java.lang.Object

org.axonframework.commandhandling.SimpleCommandBus

All Implemented Interfaces:

CommandBus, MessageDispatchInterceptorSupport<CommandMessage<?>>, MessageHandlerInterceptorSupport<CommandMessage<?>>

Direct Known Subclasses:

AsynchronousCommandBus

public class SimpleCommandBus
extends Object
implements CommandBus

Implementation of the CommandBus that dispatches commands to the handlers subscribed to that specific command's name. Interceptors may be configured to add processing to commands regardless of their type or name, for example logging, security (authorization), sla monitoring, etc.

Since:

0.5

Author:

Allard Buijze, Martin Tilma

Constructor Summary

Constructors

Constructor and Description
SimpleCommandBus() Initializes the SimpleCommandBus.
SimpleCommandBus(TransactionManager transactionManager, MessageMonitor<? super CommandMessage<?>> messageMonitor) Initializes the SimpleCommandBus with the given transactionManager and messageMonitor

Method Summary

Modifier and Type	Method and Description
<C,R> void	dispatch(CommandMessage<C> command, CommandCallback<? super C,R> callback) Dispatch the given command to the CommandHandler subscribed to the given command's name.
protected <C,R> void	doDispatch(CommandMessage<C> command, CommandCallback<? super C,R> callback) Performs the actual dispatching logic.
protected <C,R> void	handle(CommandMessage<C> command, MessageHandler<? super CommandMessage<?>> handler, CommandCallback<? super C,R> callback) Performs the actual handling logic.
protected <C> CommandMessage<C>	intercept(CommandMessage<C> command) Invokes all the dispatch interceptors.
Registration	registerDispatchInterceptor(MessageDispatchInterceptor<? super CommandMessage<?>> dispatchInterceptor) Registers the given list of dispatch interceptors to the command bus.
Registration	registerHandlerInterceptor(MessageHandlerInterceptor<? super CommandMessage<?>> handlerInterceptor) Registers the given interceptor to the command bus.
void	setRollbackConfiguration(RollbackConfiguration rollbackConfiguration) Sets the RollbackConfiguration that allows you to change when the UnitOfWork is committed.
Registration	subscribe(String commandName, MessageHandler<? super CommandMessage<?>> handler) Subscribe the given handler to commands with given commandName.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.axonframework.commandhandling.CommandBus

dispatch

Constructor Detail

SimpleCommandBus

public SimpleCommandBus()

Initializes the SimpleCommandBus. This instance shall not manage any transactions or expose any monitoring information.

SimpleCommandBus

public SimpleCommandBus(TransactionManager transactionManager,
                        MessageMonitor<? super CommandMessage<?>> messageMonitor)

Initializes the SimpleCommandBus with the given transactionManager and messageMonitor

Parameters:

transactionManager - The transactionManager to manage transaction with

messageMonitor - the message monitor to monitor the command bus

Method Detail

dispatch

public <C,R> void dispatch(CommandMessage<C> command,
                           CommandCallback<? super C,R> callback)

Description copied from interface: CommandBus

Dispatch the given command to the CommandHandler subscribed to the given command's name. When the command is processed, one of the callback's methods is called, depending on the result of the processing.

When the method returns, the only guarantee provided by the CommandBus implementation is that the command has been successfully received. Implementations are highly recommended to perform basic validation of the command before returning from this method call.

Implementations must start a UnitOfWork when before dispatching the command, and either commit or rollback after a successful or failed execution, respectively.

Specified by:

dispatch in interface CommandBus

Type Parameters:

C - The payload type of the command to dispatch

R - The type of the expected result

Parameters:

command - The Command to dispatch

callback - The callback to invoke when command processing is complete

See Also:

GenericCommandMessage.asCommandMessage(Object)

intercept

protected <C> CommandMessage<C> intercept(CommandMessage<C> command)

Invokes all the dispatch interceptors.

Parameters:

command - The original command being dispatched

Returns:

The command to actually dispatch

doDispatch

protected <C,R> void doDispatch(CommandMessage<C> command,
                                CommandCallback<? super C,R> callback)

Performs the actual dispatching logic. The dispatch interceptors must have been invoked at this point.

Type Parameters:

C - The type of payload of the command

R - The type of result expected from the command handler

Parameters:

command - The actual command to dispatch to the handler

callback - The callback to notify of the result

handle

protected <C,R> void handle(CommandMessage<C> command,
                            MessageHandler<? super CommandMessage<?>> handler,
                            CommandCallback<? super C,R> callback)

Performs the actual handling logic.

Type Parameters:

C - The type of payload of the command

R - The type of result expected from the command handler

Parameters:

command - The actual command to handle

handler - The handler that must be invoked for this command

callback - The callback to notify of the result

subscribe

public Registration subscribe(String commandName,
                              MessageHandler<? super CommandMessage<?>> handler)

Subscribe the given handler to commands with given commandName. If a subscription already exists for the given name, then the new handler takes over the subscription.

Specified by:

subscribe in interface CommandBus

Parameters:

commandName - The name of the command to subscribe the handler to

handler - The handler instance that handles the given type of command

Returns:

a handle to unsubscribe the handler. When unsubscribed it will no longer receive commands.

registerHandlerInterceptor

public Registration registerHandlerInterceptor(MessageHandlerInterceptor<? super CommandMessage<?>> handlerInterceptor)

Registers the given interceptor to the command bus. All incoming commands will pass through the registered interceptors at the given order before the command is passed to the handler for processing.

Specified by:

registerHandlerInterceptor in interface MessageHandlerInterceptorSupport<CommandMessage<?>>

Parameters:

handlerInterceptor - The interceptor to invoke when commands are handled

Returns:

handle to unregister the interceptor

registerDispatchInterceptor

public Registration registerDispatchInterceptor(MessageDispatchInterceptor<? super CommandMessage<?>> dispatchInterceptor)

Registers the given list of dispatch interceptors to the command bus. All incoming commands will pass through the interceptors at the given order before the command is dispatched toward the command handler.

Specified by:

registerDispatchInterceptor in interface MessageDispatchInterceptorSupport<CommandMessage<?>>

Parameters:

dispatchInterceptor - The interceptors to invoke when commands are dispatched

Returns:

handle to unregister the interceptor

setRollbackConfiguration

public void setRollbackConfiguration(RollbackConfiguration rollbackConfiguration)

Sets the RollbackConfiguration that allows you to change when the UnitOfWork is committed. If not set the RollbackOnUncheckedExceptionConfiguration will be used, which triggers a rollback on all unchecked exceptions.

Parameters:

rollbackConfiguration - The RollbackConfiguration.