org.axonframework.jgroups.commandhandling

Class JGroupsConnector

java.lang.Object

org.axonframework.jgroups.commandhandling.JGroupsConnector

All Implemented Interfaces:

CommandBusConnector, CommandRouter, MessageHandlerInterceptorSupport<CommandMessage<?>>, org.jgroups.MembershipListener, org.jgroups.MessageListener, org.jgroups.Receiver, org.jgroups.StateListener

public class JGroupsConnector
extends Object
implements CommandRouter, org.jgroups.Receiver, CommandBusConnector

A Connector for the DistributedCommandBus based on JGroups that acts both as the discovery and routing mechanism (implementing CommandRouter) as well as the Connector between nodes (implementing CommandBusConnector).

After configuring the Connector, it needs to connect(), before it can start dispatching messages to other nodes. For a clean shutdown, connectors should disconnect() to notify other nodes of the node leaving.

Constructor Summary

Constructors

Constructor and Description
JGroupsConnector(CommandBus localSegment, org.jgroups.JChannel channel, String clusterName, Serializer serializer) Initialize the connector using the given localSegment to handle commands on the local node, and the given channel to connect between nodes.
JGroupsConnector(CommandBus localSegment, org.jgroups.JChannel channel, String clusterName, Serializer serializer, RoutingStrategy routingStrategy) Initialize the connector using the given localSegment to handle commands on the local node, and the given channel to connect between nodes.
JGroupsConnector(CommandBus localSegment, org.jgroups.JChannel channel, String clusterName, Serializer serializer, RoutingStrategy routingStrategy, ConsistentHashChangeListener consistentHashChangeListener) Initialize the connector using the given localSegment to handle commands on the local node, and the given channel to connect between nodes.

Method Summary

Modifier and Type	Method and Description
boolean	awaitJoined() this method blocks until this member has successfully joined the other members, until the thread is interrupted, or when joining has failed.
boolean	awaitJoined(long timeout, TimeUnit timeUnit) this method blocks until this member has successfully joined the other members, until the thread is interrupted, when the given number of milliseconds have passed, or when joining has failed.
void	block()
protected void	broadCastMembership(int updateVersion, boolean expectReply) Send the local membership details (load factor and supported Command types) to other member nodes of this cluster.
void	connect() Connects this Node to the cluster and shares membership details about this node with the other nodes in the cluster.
void	disconnect() Disconnects from the Cluster, preventing any Commands from being routed to this node.
Optional<Member>	findDestination(CommandMessage<?> message) Returns the member instance to which the given message should be routed.
protected ConsistentHash	getConsistentHash() Returns the ConsistentHash instance that describes the current membership status.
String	getNodeName() Returns the name of the current node, as it is known to the Cluster.
void	getState(OutputStream ostream)
void	receive(org.jgroups.Message msg)
Registration	registerHandlerInterceptor(MessageHandlerInterceptor<? super CommandMessage<?>> handlerInterceptor) Register the given handlerInterceptor.
protected org.jgroups.Address	resolveAddress(Member destination) Resolve the JGroups Address of the given Member.
<C> void	send(Member destination, CommandMessage<? extends C> command) Sends the given command to the node assigned to handle messages with the given routingKey.
<C,R> void	send(Member destination, CommandMessage<C> command, CommandCallback<? super C,R> callback) Sends the given command to the node assigned to handle messages with the given routingKey.
void	setState(InputStream istream)
Registration	subscribe(String commandName, MessageHandler<? super CommandMessage<?>> handler) Subscribes a command message handler for commands with given commandName.
void	suspect(org.jgroups.Address suspected_mbr)
void	unblock()
void	updateMembership(int loadFactor, Predicate<? super CommandMessage<?>> commandFilter) Updates the load factor and capabilities of this member representing the current endpoint if the implementation allows memberships to be updated dynamically.
void	viewAccepted(org.jgroups.View view)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jgroups.MessageListener

receive

Constructor Detail

JGroupsConnector

public JGroupsConnector(CommandBus localSegment,
                        org.jgroups.JChannel channel,
                        String clusterName,
                        Serializer serializer)

Initialize the connector using the given localSegment to handle commands on the local node, and the given channel to connect between nodes. A unique clusterName should be chose to define which nodes can connect to each other. The given serializer is used to serialize messages when they are sent between nodes.

Commands are routed based on the TargetAggregateIdentifier

Parameters:

localSegment - The CommandBus implementation that handles the local Commands

channel - The JGroups Channel used to communicate between nodes

clusterName - The name of the Cluster

serializer - The serializer to serialize Command Messages with

JGroupsConnector

public JGroupsConnector(CommandBus localSegment,
                        org.jgroups.JChannel channel,
                        String clusterName,
                        Serializer serializer,
                        RoutingStrategy routingStrategy)

Initialize the connector using the given localSegment to handle commands on the local node, and the given channel to connect between nodes. A unique clusterName should be chose to define which nodes can connect to each other. The given serializer is used to serialize messages when they are sent between nodes. The routingStrategy is used to define the key based on which Command Messages are routed to their respective handler nodes.

Parameters:

localSegment - The CommandBus implementation that handles the local Commands

channel - The JGroups Channel used to communicate between nodes

clusterName - The name of the Cluster

serializer - The serializer to serialize Command Messages with

routingStrategy - The strategy for routing Commands to a Node

JGroupsConnector

public JGroupsConnector(CommandBus localSegment,
                        org.jgroups.JChannel channel,
                        String clusterName,
                        Serializer serializer,
                        RoutingStrategy routingStrategy,
                        ConsistentHashChangeListener consistentHashChangeListener)

Initialize the connector using the given localSegment to handle commands on the local node, and the given channel to connect between nodes. A unique clusterName should be chose to define which nodes can connect to each other. The given serializer is used to serialize messages when they are sent between nodes. The routingStrategy is used to define the key based on which Command Messages are routed to their respective handler nodes. The given consistentHashChangeCallback is notified when a change in membership has potentially caused a change in the consistent hash.

Parameters:

localSegment - The CommandBus implementation that handles the local Commands

channel - The JGroups Channel used to communicate between nodes

clusterName - The name of the Cluster

serializer - The serializer to serialize Command Messages with

routingStrategy - The strategy for routing Commands to a Node

consistentHashChangeListener - The callback to invoke when the consistent hash has changed

Method Detail

updateMembership

public void updateMembership(int loadFactor,
                             Predicate<? super CommandMessage<?>> commandFilter)

Description copied from interface: CommandRouter

Updates the load factor and capabilities of this member representing the current endpoint if the implementation allows memberships to be updated dynamically.

Specified by:

updateMembership in interface CommandRouter

Parameters:

loadFactor - the new load factor of the member for this endpoint

commandFilter - the new capabilities of the member for this endpoint

broadCastMembership

protected void broadCastMembership(int updateVersion,
                                   boolean expectReply)
                            throws ServiceRegistryException

Send the local membership details (load factor and supported Command types) to other member nodes of this cluster.

Parameters:

updateVersion - The version for the update to be send with the membership information

expectReply -

Throws:

ServiceRegistryException - when an exception occurs sending membership details to other nodes

connect

public void connect()
             throws Exception

Connects this Node to the cluster and shares membership details about this node with the other nodes in the cluster.

The Join messages have been sent, but may not have been processed yet when the method returns. Before sending messages via this connector, await for the joining process to be completed (see and {@link #awaitJoined(long, TimeUnit)}.

Throws:

Exception - when an error occurs connecting or communicating with the cluster

disconnect

public void disconnect()

Disconnects from the Cluster, preventing any Commands from being routed to this node.

getState

public void getState(OutputStream ostream)

Specified by:

getState in interface org.jgroups.StateListener

setState

public void setState(InputStream istream)

Specified by:

setState in interface org.jgroups.StateListener

viewAccepted

public void viewAccepted(org.jgroups.View view)

Specified by:

viewAccepted in interface org.jgroups.MembershipListener

suspect

public void suspect(org.jgroups.Address suspected_mbr)

Specified by:

suspect in interface org.jgroups.MembershipListener

block

public void block()

Specified by:

block in interface org.jgroups.MembershipListener

unblock

public void unblock()

Specified by:

unblock in interface org.jgroups.MembershipListener

receive

public void receive(org.jgroups.Message msg)

Specified by:

receive in interface org.jgroups.MessageListener

awaitJoined

public boolean awaitJoined()
                    throws InterruptedException

this method blocks until this member has successfully joined the other members, until the thread is interrupted, or when joining has failed.

Returns:

true if the member successfully joined, otherwise false.

Throws:

InterruptedException - when the thread is interrupted while joining

awaitJoined

public boolean awaitJoined(long timeout,
                           TimeUnit timeUnit)
                    throws InterruptedException

this method blocks until this member has successfully joined the other members, until the thread is interrupted, when the given number of milliseconds have passed, or when joining has failed.

Parameters:

timeout - The amount of time to wait for the connection to complete

timeUnit - The time unit of the timeout

Returns:

true if the member successfully joined, otherwise false.

Throws:

InterruptedException - when the thread is interrupted while joining

getNodeName

public String getNodeName()

Returns the name of the current node, as it is known to the Cluster.

Returns:

the name of the current node

getConsistentHash

protected ConsistentHash getConsistentHash()

Returns the ConsistentHash instance that describes the current membership status. The ConsistentHash is used to decide which node is to be sent a Message.

Returns:

the ConsistentHash instance that describes the current membership status

send

public <C> void send(Member destination,
                     CommandMessage<? extends C> command)
              throws Exception

Description copied from interface: CommandBusConnector

Sends the given command to the node assigned to handle messages with the given routingKey. The sender does not expect a reply.

If this method throws an exception, the sender is guaranteed that the destination of the command did not receive it. If the method returns normally, the actual implementation of the connector defines the delivery guarantees.

Connectors route the commands based on the given routingKey. Using the same routingKey will result in the command being sent to the same member. Each message must be sent to exactly one member.

Specified by:

send in interface CommandBusConnector

Parameters:

destination - The member of the network to send the message to

command - The command to send to the (remote) member

Throws:

Exception - when an error occurs before or during the sending of the message

send

public <C,R> void send(Member destination,
                       CommandMessage<C> command,
                       CommandCallback<? super C,R> callback)
                throws Exception

Description copied from interface: CommandBusConnector

Sends the given command to the node assigned to handle messages with the given routingKey. The sender expect a reply, and will be notified of the result in the given callback.

If this method throws an exception, the sender is guaranteed that the destination of the command did not receive it. If the method returns normally, the actual implementation of the connector defines the delivery guarantees. Implementations should always invoke the callback with an outcome.

If a member's connection was lost, and the result of the command is unclear, the CommandCallback.onFailure(org.axonframework.commandhandling.CommandMessage, Throwable) method is invoked with a RemoteCommandHandlingException describing the failed connection. A client may choose to resend a command.

Connectors route the commands based on the given routingKey. Using the same routingKey will result in the command being sent to the same member.

Specified by:

send in interface CommandBusConnector

Type Parameters:

C - The type of object expected as command

R - The type of object expected as result of the command

Parameters:

destination - The member of the network to send the message to

command - The command to send to the (remote) member

callback - The callback

Throws:

Exception - when an error occurs before or during the sending of the message

subscribe

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

Description copied from interface: CommandBusConnector

Subscribes a command message handler for commands with given commandName.

Specified by:

subscribe in interface CommandBusConnector

Parameters:

commandName - the command name. Usually this equals the fully qualified class name of the command.

handler - the handler to subscribe

Returns:

a handle that can be used to end the subscription

resolveAddress

protected org.jgroups.Address resolveAddress(Member destination)

Resolve the JGroups Address of the given Member.

Parameters:

destination - The node of which to solve the Address

Returns:

The JGroups Address of the given node

Throws:

CommandBusConnectorCommunicationException - when an error occurs resolving the adress

findDestination

public Optional<Member> findDestination(CommandMessage<?> message)

Description copied from interface: CommandRouter

Returns the member instance to which the given message should be routed. If no suitable member could be found an empty Optional is returned.

Specified by:

findDestination in interface CommandRouter

Parameters:

message - the command message to find a member for

Returns:

the member that should handle the message or an empty Optional if no suitable member was found

registerHandlerInterceptor

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

Description copied from interface: MessageHandlerInterceptorSupport

Register the given handlerInterceptor. After registration, the interceptor will be invoked for each handled Message on the messaging component that it was registered to, prior to invoking the message's handler.

Specified by:

registerHandlerInterceptor in interface MessageHandlerInterceptorSupport<CommandMessage<?>>

Parameters:

handlerInterceptor - The interceptor to register

Returns:

a Registration, which may be used to remove the unregister the interceptor