Distributed Messaging and Events

Apache Ignite® provides high-performance cluster-wide messaging functionality to exchange data via publish-subscribe and direct point-to-point communication models. Messages can be exchanged in an ordered or unordered fashion. Ordered messages are slightly slower, but when used, Ignite guarantees that messages will be received in the same order they were sent.

Ignite distributed events functionality allows applications to receive notifications when a variety of events occur in the distributed grid environment. You can automatically get notified for task executions, read, write or query operations occurring on local or remote nodes within the cluster. Event notifications can also be grouped together and sent in batches or timely intervals.

Code Examples:

                    Ignite ignite = Ignition.ignite();

                    IgniteMessaging rmtMsg = ignite.message(ignite.cluster().forRemotes());

                    // Add listener for ordered messages on all remote nodes.
                    rmtMsg.remoteListen("MyOrderedTopic", (nodeId, msg) -> {
                        System.out.println("Received ordered message [msg=" + msg + ", from=" + nodeId + ']');

                        return true; // Return true to continue listening.
                    });

                    // Send ordered messages to remote nodes.
                    for (int i = 0; i < 10; i++)
                        rmtMsg.sendOrdered("MyOrderedTopic", Integer.toString(i), 0);
                
                    Ignite ignite = Ignition.ignite();

                    IgniteMessaging rmtMsg = ignite.message(ignite.cluster().forRemotes());

                    // Add listener for unordered messages on all remote nodes.
                    rmtMsg.remoteListen("MyUnOrderedTopic", (nodeId, msg) -> {
                        System.out.println("Received unordered message [msg=" + msg + ", from=" + nodeId + ']');

                        return true; // Return true to continue listening.
                    });

                    // Send unordered messages to remote nodes.
                    for (int i = 0; i < 10; i++)
                        rmtMsg.send("MyUnOrderedTopic", Integer.toString(i));
                
                    Ignite ignite = Ignition.ignite();

                    // Local listener that listenes to local events.
                    IgnitePredicate<CacheEvent> locLsnr = evt -> {
                        System.out.println("Received local event [evt=" + evt.name() + "]");

                        return true; // Continue listening.
                    };

                    // Subscribe to specified cache events occuring on local node.
                    ignite.events().localListen(locLsnr,
                        EventType.EVT_CACHE_OBJECT_PUT,
                        EventType.EVT_CACHE_OBJECT_REMOVED);

                    // Get an instance of named cache.
                    final IgniteCache<Integer, String> cache = ignite.cache("cacheName");

                    // Generate cache events.
                    for (int i = 0; i < 20; i++)
                        cache.put(i, Integer.toString(i));
                
                    Ignite ignite = Ignition.ignite();

                    // Get an instance of named cache.
                    final IgniteCache<Integer, String> cache = ignite.jcache("cacheName");

                    // Sample remote filter which only accepts events for keys
                    // that are greater than or equal to 10.
                    IgnitePredicate<CacheEvent> rmtLsnr = evt -> {
                        System.out.println("Received remote event [evt=" + evt.<Integer>key() >= 10 + "]");

                        return true; // Continue listening.
                    };

                    // Subscribe to specified cache events on all nodes that have cache running.
                    ignite.events(ignite.cluster().forCacheNodes("cacheName")).remoteListen(null, rmtLsnr,
                        EventType.EVT_CACHE_OBJECT_PUT,
                        EventType.EVT_CACHE_OBJECT_REMOVED);

                    // Generate cache events.
                    for (int i = 0; i < 20; i++)
                        cache.put(i, Integer.toString(i));

GitHub Examples:

Also see messaging examplesavailable on GitHub.

Messaging & Events Features

Feature Description
Topic Based Messaging

Ignite distributed messaging allows for topic based cluster-wide communication between all nodes.

Docs for this feature
Point-to-Point Messaging

Ignite messages can be sent to either a group of nodes or to an individual node.

Docs for this Feature
Ordered vs. Unordered

Ignite supports ordered and unordered messages. Ordered messages are slightly slower, but when used, Ignite guarantees that messages will be received in the same order they were sent.

Docs for this Feature
Event Notifications

Ignite distributed events functionality allows applications to receive notifications when a variety of events occur within the cluster.

Docs for this feature
Local vs. Remote Events

Applications can get notified for task executions, read, write or query operations occurring on local or remote nodes within the cluster.

Docs for this feature
Automatic Batching

Event notifications can be grouped together and sent in batches or timely intervals.

Docs for this feature