Package com.opencqrs.framework.command

Class CommandRouter

java.lang.Object

com.opencqrs.framework.command.CommandRouter

public final class CommandRouter
extends Object

Command router implementation providing CQRS-style command execution.

See Also:

• send(Command, Map)

Constructor Summary

Constructors

Constructor	Description
CommandRouter(EventReader eventReader, ImmediateEventPublisher immediateEventPublisher, List<CommandHandlerDefinition> commandHandlerDefinitions, List<StateRebuildingHandlerDefinition> stateRebuildingHandlerDefinitions)	Creates a pre-configured instance of this with disabled meta-data propagation and NoStateRebuildingCache.
CommandRouter(EventReader eventReader, ImmediateEventPublisher immediateEventPublisher, List<CommandHandlerDefinition> commandHandlerDefinitions, List<StateRebuildingHandlerDefinition> stateRebuildingHandlerDefinitions, StateRebuildingCache stateRebuildingCache, PropagationMode propagationMode, Set<String> propagationKeys)	Creates a pre-configured instance of this.

Method Summary

Modifier and Type	Method	Description
<R> R	send(Command command)	Sends the given command with empty meta-data to the appropriate CommandHandler for execution.
<R> R	send(Command command, Map<String,?> metaData)	Sends the given command and meta-data to the appropriate CommandHandler for execution.

Methods inherited from class java.lang.Object

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

Constructor Details

CommandRouter

public CommandRouter(EventReader eventReader,
 ImmediateEventPublisher immediateEventPublisher,
 List<CommandHandlerDefinition> commandHandlerDefinitions,
 List<StateRebuildingHandlerDefinition> stateRebuildingHandlerDefinitions,
 StateRebuildingCache stateRebuildingCache,
 PropagationMode propagationMode,
 Set<String> propagationKeys)

Creates a pre-configured instance of this.

Parameters:

eventReader - the event source

immediateEventPublisher - the event sink

commandHandlerDefinitions - a non-empty list of command handler definitions to be executable

stateRebuildingHandlerDefinitions - a non-empty list of state rebuilding handler definitions used for event-sourcing

stateRebuildingCache - the cache to use for state rebuilding

propagationMode - the propagation sourcingMode for command meta-data

propagationKeys - the command meta-data keys to propagate, if necessary

CommandRouter

public CommandRouter(EventReader eventReader,
 ImmediateEventPublisher immediateEventPublisher,
 List<CommandHandlerDefinition> commandHandlerDefinitions,
 List<StateRebuildingHandlerDefinition> stateRebuildingHandlerDefinitions)

Creates a pre-configured instance of this with disabled meta-data propagation and NoStateRebuildingCache.

Parameters:

eventReader - the event source

immediateEventPublisher - the event sink

commandHandlerDefinitions - a non-empty list of command handler definitions to be executable

stateRebuildingHandlerDefinitions - a non-empty list of state rebuilding handler definitions used for event-sourcing

Method Details

send

public <R> R send(Command command)

Sends the given command with empty meta-data to the appropriate CommandHandler for execution. The command execution process involves the following:

1. the matching CommandHandler is determined
2. the instance type for state rebuilding is determined
3. all matching StateRebuildingHandlers are determined
4. the StateRebuildingCache is fetched
5. newer (than cached) events are EventReader.consumeAsObject(EventReader.ClientRequestor, BiConsumer) read} from the underlying event store, upcasted and converted to Java objects
6. the Command.getSubjectCondition() is checked
7. the events are applied to all matching StateRebuildingHandlers to reconstruct the instance state
8. the cache is updated with the reconstructed instance state
9. the command is executed on the instance
10. all events captured as part of the command execution are published atomically to the underlying event store
11. the CommandHandler result is returned to the caller

No events will be published in case of an exception thrown from any of the involved handlers.

Type Parameters:

R - the result type

Parameters:

command - the command to be executed

Returns:

the result from the CommandHandler, may be null

send

public <R> R send(Command command,
 Map<String,?> metaData)

Sends the given command and meta-data to the appropriate CommandHandler for execution. The command execution process involves the following:

1. the matching CommandHandler is determined
2. the instance type for event-sourcing is determined
3. all matching StateRebuildingHandlers are determined
4. the StateRebuildingCache is fetched
5. newer (than cached) events are EventReader.consumeAsObject(EventReader.ClientRequestor, BiConsumer) read} from the underlying event store, upcasted and converted to Java objects
6. the Command.getSubjectCondition() is checked
7. the events are applied to all matching StateRebuildingHandlers to reconstruct the instance state
8. the cache is updated with the reconstructed instance state
9. the command is executed on the instance
10. all events captured as part of the command execution are applied with propagated command meta-data
11. the events are published atomically to the underlying event store
12. the CommandHandler result is returned to the caller

No events will be published in case of an exception thrown from any of the involved handlers.

Type Parameters:

R - the result type

Parameters:

command - the command to be executed

metaData - the meta-data to be passed to the command handler

Returns:

the result from the CommandHandler, may be null