public class DistributedPubSubMediator
extends java.lang.Object
implements akka.actor.Actor, akka.actor.ActorLogging
The DistributedPubSubMediator
actor is supposed to be started on all nodes,
or all nodes with specified role, in the cluster. The mediator can be
started with the DistributedPubSub
extension or as an ordinary actor.
Changes are only performed in the own part of the registry and those changes are versioned. Deltas are disseminated in a scalable way to other nodes with a gossip protocol. The registry is eventually consistent, i.e. changes are not immediately visible at other nodes, but typically they will be fully replicated to all other nodes after a few seconds.
You can send messages via the mediator on any node to registered actors on any other node. There is three modes of message delivery.
1. DistributedPubSubMediator.Send
-
The message will be delivered to one recipient with a matching path, if any such
exists in the registry. If several entries match the path the message will be sent
via the supplied routingLogic
(default random) to one destination. The sender of the
message can specify that local affinity is preferred, i.e. the message is sent to an actor
in the same local actor system as the used mediator actor, if any such exists, otherwise
route to any other matching entry. A typical usage of this mode is private chat to one
other user in an instant messaging application. It can also be used for distributing
tasks to registered workers, like a cluster aware router where the routees dynamically
can register themselves.
2. DistributedPubSubMediator.SendToAll
-
The message will be delivered to all recipients with a matching path. Actors with
the same path, without address information, can be registered on different nodes.
On each node there can only be one such actor, since the path is unique within one
local actor system. Typical usage of this mode is to broadcast messages to all replicas
with the same path, e.g. 3 actors on different nodes that all perform the same actions,
for redundancy.
3. DistributedPubSubMediator.Publish
-
Actors may be registered to a named topic instead of path. This enables many subscribers
on each node. The message will be delivered to all subscribers of the topic. For
efficiency the message is sent over the wire only once per node (that has a matching topic),
and then delivered to all subscribers of the local topic representation. This is the
true pub/sub mode. A typical usage of this mode is a chat room in an instant messaging
application.
4. DistributedPubSubMediator.Publish
with sendOneMessageToEachGroup -
Actors may be subscribed to a named topic with an optional property group
.
If subscribing with a group name, each message published to a topic with the
sendOneMessageToEachGroup
flag is delivered via the supplied routingLogic
(default random) to one actor within each subscribing group.
If all the subscribed actors have the same group name, then this works just like
DistributedPubSubMediator.Send
and all messages are delivered to one subscribe.
If all the subscribed actors have different group names, then this works like normal
DistributedPubSubMediator.Publish
and all messages are broadcast to all subscribers.
You register actors to the local mediator with DistributedPubSubMediator.Put
or
DistributedPubSubMediator.Subscribe
. Put
is used together with Send
and
SendToAll
message delivery modes. The ActorRef
in Put
must belong to the same
local actor system as the mediator. Subscribe
is used together with Publish
.
Actors are automatically removed from the registry when they are terminated, or you
can explicitly remove entries with DistributedPubSubMediator.Remove
or
DistributedPubSubMediator.Unsubscribe
.
Successful Subscribe
and Unsubscribe
is acknowledged with
DistributedPubSubMediator.SubscribeAck
and DistributedPubSubMediator.UnsubscribeAck
replies.
Constructor and Description |
---|
DistributedPubSubMediator(akka.cluster.pubsub.DistributedPubSubSettings settings) |
Modifier and Type | Method and Description |
---|---|
akka.cluster.Cluster |
cluster() |
scala.collection.immutable.Iterable<akka.cluster.pubsub.DistributedPubSubMediator.Internal.Bucket> |
collectDelta(scala.collection.immutable.Map<akka.actor.Address,java.lang.Object> otherVersions) |
scala.collection.immutable.Set<java.lang.String> |
getCurrentTopics() |
static DistributedPubSubMediator.GetTopics |
getTopicsInstance()
Java API: Send this message to the mediator and it will reply with
DistributedPubSubMediator.CurrentTopics containing the names of the (currently known)
registered topic names. |
void |
gossip()
Gossip to peer nodes.
|
akka.actor.Cancellable |
gossipTask() |
void |
gossipTo(akka.actor.Address address) |
boolean |
matchingRole(akka.cluster.Member m) |
java.lang.String |
mkKey(akka.actor.ActorPath path) |
java.lang.String |
mkKey(akka.actor.ActorRef ref) |
scala.collection.immutable.Map<akka.actor.Address,java.lang.Object> |
myVersions() |
scala.Function0<java.lang.Object> |
nextVersion() |
scala.collection.immutable.Set<akka.actor.Address> |
nodes() |
boolean |
otherHasNewerVersions(scala.collection.immutable.Map<akka.actor.Address,java.lang.Object> otherVersions) |
void |
postStop() |
void |
preStart() |
static akka.actor.Props |
props(akka.cluster.pubsub.DistributedPubSubSettings settings)
Scala API: Factory method for
DistributedPubSubMediator Props . |
void |
prune() |
scala.concurrent.duration.FiniteDuration |
pruneInterval() |
akka.actor.Cancellable |
pruneTask() |
void |
publish(java.lang.String path,
java.lang.Object msg,
boolean allButSelf) |
void |
publishToEachGroup(java.lang.String path,
java.lang.Object msg) |
void |
put(java.lang.String key,
scala.Option<akka.actor.ActorRef> valueOption) |
scala.PartialFunction<java.lang.Object,scala.runtime.BoxedUnit> |
receive() |
void |
registerTopic(akka.actor.ActorRef ref) |
scala.collection.immutable.Map<akka.actor.Address,akka.cluster.pubsub.DistributedPubSubMediator.Internal.Bucket> |
registry() |
long |
removedTimeToLiveMillis() |
scala.Option<akka.actor.Address> |
selectRandomNode(scala.collection.immutable.IndexedSeq<akka.actor.Address> addresses) |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public DistributedPubSubMediator(akka.cluster.pubsub.DistributedPubSubSettings settings)
public static akka.actor.Props props(akka.cluster.pubsub.DistributedPubSubSettings settings)
DistributedPubSubMediator
Props
.settings
- (undocumented)public static DistributedPubSubMediator.GetTopics getTopicsInstance()
DistributedPubSubMediator.CurrentTopics
containing the names of the (currently known)
registered topic names.public akka.cluster.Cluster cluster()
public long removedTimeToLiveMillis()
public akka.actor.Cancellable gossipTask()
public scala.concurrent.duration.FiniteDuration pruneInterval()
public akka.actor.Cancellable pruneTask()
public scala.collection.immutable.Map<akka.actor.Address,akka.cluster.pubsub.DistributedPubSubMediator.Internal.Bucket> registry()
public scala.collection.immutable.Set<akka.actor.Address> nodes()
public scala.Function0<java.lang.Object> nextVersion()
public void preStart()
preStart
in interface akka.actor.Actor
public void postStop()
postStop
in interface akka.actor.Actor
public boolean matchingRole(akka.cluster.Member m)
public scala.PartialFunction<java.lang.Object,scala.runtime.BoxedUnit> receive()
receive
in interface akka.actor.Actor
public void publish(java.lang.String path, java.lang.Object msg, boolean allButSelf)
public void publishToEachGroup(java.lang.String path, java.lang.Object msg)
public void put(java.lang.String key, scala.Option<akka.actor.ActorRef> valueOption)
public scala.collection.immutable.Set<java.lang.String> getCurrentTopics()
public void registerTopic(akka.actor.ActorRef ref)
public java.lang.String mkKey(akka.actor.ActorRef ref)
public java.lang.String mkKey(akka.actor.ActorPath path)
public scala.collection.immutable.Map<akka.actor.Address,java.lang.Object> myVersions()
public scala.collection.immutable.Iterable<akka.cluster.pubsub.DistributedPubSubMediator.Internal.Bucket> collectDelta(scala.collection.immutable.Map<akka.actor.Address,java.lang.Object> otherVersions)
public boolean otherHasNewerVersions(scala.collection.immutable.Map<akka.actor.Address,java.lang.Object> otherVersions)
public void gossip()
public void gossipTo(akka.actor.Address address)
public scala.Option<akka.actor.Address> selectRandomNode(scala.collection.immutable.IndexedSeq<akka.actor.Address> addresses)
public void prune()