Cache and Cache Manger events in CDI

A long time ago, in a coffee bar far, far away, Infinispan met CDI. The two had the most amazing espressos, but they noticed that service was not as efficient as they wished. To help them out, the CDI support has been extended to include CDI Events.

Coffee Events

In case you haven't heard about CDI events, here is a really quick example:

	@Qualifier
	@Retention(RUNTIME)
	@Target({TYPE, METHOD, FIELD, PARAMETER})
	public @interface CoffeeOrdered {
	}
	public class Waiter {
	@CoffeeOrdered
	@Inject
	Event<Coffee> orderCoffee;
	public void takeOrder(Coffee coffee) {
	orderCoffee.fire(coffee);
	}
	}
	public class Barista {
	public void prepareCoffee(@CoffeeOrdered @Observes Coffee coffee) {
	....
	}
	}

view raw CDI - Coffee example hosted with ❤ by GitHub

When Waiter receives an order - he fires a CDI event. On the other hand Barista acts as a listener for ordered coffees (@CoffeeOrdered and @Observes). As a result Barista and Waiter are loosely coupled and moreover they don't know anything about each other.

Cache based Coffee Events

Now let's complicate this situation a little bit... Let's assume that when Waiter is passing an order to Barista, he might be actually busy processing another order. So let's introduce a little buffer between them - Waiter puts an order into the Cache and later on - Barista takes it and prepares our delicious coffee...

	@Qualifier
	@Retention(RUNTIME)
	@Target({TYPE, METHOD, FIELD, PARAMETER})
	public @interface CoffeeOrdered {
	}
	public class Waiter {
	@Inject
	@CoffeeOrdered
	Cache<String, Coffee> orderedCoffees;
	public void takeOrder(Coffee coffee) {
	orderedCoffees.put(UUID.randomUUID().toString(), coffee);
	}
	}
	public class Barista {
	@Inject
	@CoffeeOrdered
	Cache<String, Coffee> orderedCoffees;
	public void prepareCoffee(@CoffeeOrdered @Observes CacheEntryCreatedEvent coffee) {
	if(haveTime()) {
	prepareDelicious(coffee);
	} else {
	// continue doing something else
	// later use orderedCoffees methods, for example orderedCoffees.keySet()
	}
	}
	...
	}

view raw CDI - Coffee and Infinispan example hosted with ❤ by GitHub

Beyond good espressos

As you can see - introducing CDI improved the service a lot. Now Waiter does not hurry Barista with the orders. This is why they serve the best espresso in the world there...

They have also a lot more time to think about other improvements (and to be honest... I think they will introduce CacheEntryModifiedEvent, CacheEntryRemovedEvent and CacheStartedEvent really shortly)... Or perhaps they'll find some other ideas in Infinispan's manual?

Hot Rod Remote Events #3: Customizing events

This blog post is the third in a series that looks at the forthcoming Hot Rod Remote Events functionality included in Infinispan 7.0. In the first article we looked at how to get started receiving remote events from Hot Rod servers. In the second article, we saw how Hot Rod remote events can be filtered providing key/value filter factories that can create instances that filter which events are sent to clients, and how these filters can act on client provided information.

This time we are going to focus on how to customize events sent to clients. Events generated by default contain just enough information to make the event relevant but avoid cramming too much information in order to reduce the cost of sending them. Normally, this information consists of key and type of event.

Optionally, the information shipped in these events can be customized in order to contain more information, such as values, or to contain even less information. This customization is done with org.infinispan.notifications.cachelistener.filter.CacheEventConverter instances which are created by implementing a org.infinispan.notifications.cachelistener.filter.CacheEventConverterFactory class. Each factory must have a name associated to it via the org.infinispan.filter.NamedFactory annotation.

When a listener is added, we can provide the name of a converter factory to use with this listener, and when the listener is added, the server will look up the factory and invoke getConverter method to get a org.infinispan.notifications.cachelistener.filter.CacheEventConverter class instance to customize events server side.

Here's a sample implementation which will send custom events containing value information back to clients for a cache of Integers and Strings:

	import org.infinispan.notifications.cachelistener.filter.*;
	import org.infinispan.metadata.Metadata;
	@NamedFactory(name = "value-added-converter-factory")
	class ValueAddedConverterFactory implements CacheEventConverterFactory {
	public CacheEventConverter<Integer, String, ValueAddedEvent> getConverter(final Object[] params) {
	return new ValueAddedConverter();
	}
	static class ValueAddedConverter implements CacheEventConverter<Integer, String, ValueAddedEvent> {
	public ValueAddedEvent convert(Integer key, String oldValue, Metadata oldMetadata,
	String newValue, Metadata newMetadata, EventType eventType) {
	return new ValueAddedEvent(key, value);
	}
	}
	}
	// Needs to be Serializable or Externalizable!
	class ValueAddedEvent implements Serializable {
	final Integer key;
	final String value;
	ValueAddedEvent(Integer key, String value) {
	this.key = key;
	this.value = value;
	}
	}

view raw gistfile1.java hosted with ❤ by GitHub

In the example above, the converter generates a new custom event which includes the value as well as the key in the event. This will result in bigger event payloads compared with default events, but if combined with filtering, it can reduce its network bandwidth cost.

In another converter implementation, the user could decide to send back an event that contains no key or event type information. This would result in extremely lightweight events at the expense of richness of information provided by the event itself.

Plugging the server with this converter requires deploying this converter factory (and associated converter class) within a jar file including a service definition inside the META-INF/services/org.infinispan.notifications.cachelistener.filter.CacheEventConverterFactory file:

sample.ValueAddedConverterFactory

view raw META-INF\services\org.infinispan.notifications.cachelistener.filter.CacheEventConverterFactory hosted with ❤ by GitHub

With the server plugged with the converter, the next step is adding a remote client listener that will use this converter. How to implement a listener for custom events is slightly different to the listeners we've seen in the last couple of blog posts because we know have to deal with customised events as opposed to the default ones. To do so, the same annotations are used as previous blog posts, but the callbacks receive instances of org.infinispan.client.hotrod.event.ClientCacheEntryCustomEvent<T>, where T is the type of custom event we are sending from the server:

	import org.infinispan.client.hotrod.annotation.*;
	import org.infinispan.client.hotrod.event.*;
	@ClientListener(converterFactoryName = "value-added-converter-factory")
	public class CustomEventLogListener {
	@ClientCacheEntryCreated
	@ClientCacheEntryModified
	@ClientCacheEntryRemoved
	public void handleRemoteEvent(ClientCacheEntryCustomEvent<ValueAddedEvent> e) {
	System.out.println(event);
	}
	}

view raw gistfile1.java hosted with ❤ by GitHub

Now it's time to write a simple main java class which adds the remote event listener and executes some operations against the remote cache:

	import org.infinispan.client.hotrod.*;
	RemoteCacheManager rcm = new RemoteCacheManager();
	RemoteCache<Integer, String> cache = rcm.getCache();
	CustomEventLogListener listener = new CustomEventLogListener();
	try {
	cache.addClientListener(listener);
	cache.put(1, "one");
	cache.put(1, "new-one");
	cache.remove(1);
	} finally {
	cache.removeClientListener(listener);
	}

view raw gistfile1.java hosted with ❤ by GitHub

Once executed, we should see a console console output similar to this:

	ClientCacheEntryCustomEvent(eventData=ValueAddedEvent{key=1, value='one'}, eventType=CLIENT_CACHE_ENTRY_CREATED)
	ClientCacheEntryCustomEvent(eventData=ValueAddedEvent{key=1, value='new-one'}, eventType=CLIENT_CACHE_ENTRY_MODIFIED)
	ClientCacheEntryCustomEvent(eventData=ValueAddedEvent{key=1, value='null'}, eventType=CLIENT_CACHE_ENTRY_REMOVED)

view raw gistfile1.txt hosted with ❤ by GitHub

Similar to events, converters can also act on client provided information, enabling converter instances to customize events depending on the information given when the listener was added. The API provides an extra parameter to pass in converter parameters when the listener is added. Given the similarities with filtering, this part is not covered by this blog post.

A final note on the marshalling aspects of this example. In order to facilitate both server and client writing against type safe APIs, both the client and server need to be aware of custom event type and be able to marshall it. Client side, this is done by an optional marshaller configurable via the RemoteCacheManager. Server side, this is done by a marshaller recently added to the Hot Rod server configuration.

In the next blog post in the Hot Rod remote events series, we will look at how to receive remote events in a clustered environment, how to deal with failover situations...etc.

Cheers,
Galder

Infinispan 7.0.0.Beta2 is out!

Dear Infinispan Community,

We are happy to announce the second Beta release of Infinispan 7.0.0!

This release brings many improvements and fixes:

• Many fixes and performance optimizations for non-indexed queries (ISPN-4670, ISPN-4700)
• Significant improvements to the reliability of indexed (i.e. Lucene based) queries:
• InfinispanIndexManager reworked to handle locking on topology changes (ISPN-4599)
• MassIndexer 20x performance improvement (ISPN-4644)
• Some race conditions fixed in the Lucene Directory (ISPN-2981)
• Fixed serialization of indexing messages under high load (ISPN-4573)
• Resolved a race condition in (indexed) Cache initializations (ISPN-4719)
• Improved classloading when run in containers (ISPN-4226, ISPN-4667)
• Fixed JBoss modules to use Externalizers when run in containers (ISPN-4685)
• (and many more minor improvements)

• ISPN-4574 - Partition handling improvements for replicated caches and distributed caches with numOwners > cluster size / 2
• ISPN-4646 - Eviction performance improvements, thanks to Karsten Blees

For a complete list of features and bug fixes included in this release please refer to the release notes.  Visit our downloads section to find the latest release.

If you have any questions please check our forums, our mailing lists or ping us directly on IRC.

Cheers,

The Infinispan team.