Chapter 88. Ehcache Component

Available as of Camel version 2.18

The ehcache component enables you to perform caching operations using Ehcache 3 as the Cache Implementation.

This component supports producer and event based consumer endpoints.

The Cache consumer is an event based consumer and can be used to listen and respond to specific cache activities. 

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-ehcache</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

88.1. URI format

ehcache://cacheName[?options]

You can append query options to the URI in the following format, ?option=value&option=#beanRef&…​

88.2. Options

The Ehcache component supports 7 options which are listed below.

NameDescriptionDefaultType

configuration (advanced)

Sets the global component configuration

 

EhcacheConfiguration

cacheManager (common)

The cache manager

 

CacheManager

cacheManager Configuration (common)

The cache manager configuration

 

Configuration

cacheConfiguration (common)

The default cache configuration to be used to create caches.

 

CacheConfiguration<?,?>

cachesConfigurations (common)

A map of caches configurations to be used to create caches.

 

Map

cacheConfigurationUri (common)

URI pointing to the Ehcache XML configuration file’s location

 

String

resolveProperty Placeholders (advanced)

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

boolean

The Ehcache endpoint is configured using URI syntax:

ehcache:cacheName

with the following path and query parameters:

88.2.1. Path Parameters (1 parameters):

NameDescriptionDefaultType

cacheName

Required the cache name

 

String

88.2.2. Query Parameters (17 parameters):

NameDescriptionDefaultType

cacheManager (common)

The cache manager

 

CacheManager

cacheManagerConfiguration (common)

The cache manager configuration

 

Configuration

configurationUri (common)

URI pointing to the Ehcache XML configuration file’s location

 

String

createCacheIfNotExist (common)

Configure if a cache need to be created if it does exist or can’t be pre-configured.

true

boolean

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

eventFiring (consumer)

Set the the delivery mode (synchronous, asynchronous)

ASYNCHRONOUS

EventFiring

eventOrdering (consumer)

Set the the delivery mode (ordered, unordered)

ORDERED

EventOrdering

eventTypes (consumer)

Set the type of events to listen for

EVICTED,EXPIRED,REMOVED,CREATED,UPDATED

Set

exceptionHandler (consumer)

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.

 

ExceptionHandler

exchangePattern (consumer)

Sets the exchange pattern when the consumer creates an exchange.

 

ExchangePattern

action (producer)

To configure the default cache action. If an action is set in the message header, then the operation from the header takes precedence.

 

String

key (producer)

To configure the default action key. If a key is set in the message header, then the key from the header takes precedence.

 

Object

configuration (advanced)

The default cache configuration to be used to create caches.

 

CacheConfiguration<?,?>

configurations (advanced)

A map of cache configuration to be used to create caches.

 

Map

keyType (advanced)

The cache key type, default java.lang.Object

java.lang.Object

String

synchronous (advanced)

Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).

false

boolean

valueType (advanced)

The cache value type, default java.lang.Object

java.lang.Object

String

88.2.3. Message Headers Camel 

 
HeaderTypeDescription

CamelEhcacheAction

String

The operation to be perfomed on the cache, valid options are:

* CLEAR * PUT * PUT_ALL * PUT_IF_ABSENT * GET * GET_ALL * REMOVE * REMOVE_ALL * REPLACE

CamelEhcacheActionHasResult

Boolean

Set to true if the action has a result

CamelEhcacheActionSucceeded

Boolean

Set to true if the actionsuccedded

CamelEhcacheKey

Object

The cache key used for an action

CamelEhcacheKeys

Set<Object>

A list of keys, used in

* PUT_ALL * GET_ALL * REMOVE_ALL

CamelEhcacheValue

Object

The value to put in the cache or the result of an operation

CamelEhcacheOldValue

Object

The old value associated to a key for actions like PUT_IF_ABSENT or the Object used for comparison for actions like REPLACE

CamelEhcacheEventType

EventType

The type of event received

88.3. Ehcache based idempotent repository example:

CacheManager manager = CacheManagerBuilder.newCacheManager(new XmlConfiguration("ehcache.xml"));
EhcacheIdempotentRepository repo = new EhcacheIdempotentRepository(manager, "idempotent-cache");

from("direct:in")
    .idempotentConsumer(header("messageId"), idempotentRepo)
    .to("mock:out");
 

88.4. Ehcache based aggregation repository example:

public class EhcacheAggregationRepositoryRoutesTest extends CamelTestSupport {
    private static final String ENDPOINT_MOCK = "mock:result";
    private static final String ENDPOINT_DIRECT = "direct:one";
    private static final int[] VALUES = generateRandomArrayOfInt(10, 0, 30);
    private static final int SUM = IntStream.of(VALUES).reduce(0, (a, b) -> a + b);
    private static final String CORRELATOR = "CORRELATOR";

    @EndpointInject(uri = ENDPOINT_MOCK)
    private MockEndpoint mock;

    @Produce(uri = ENDPOINT_DIRECT)
    private ProducerTemplate producer;

    @Test
    public void checkAggregationFromOneRoute() throws Exception {
        mock.expectedMessageCount(VALUES.length);
        mock.expectedBodiesReceived(SUM);

        IntStream.of(VALUES).forEach(
            i -> producer.sendBodyAndHeader(i, CORRELATOR, CORRELATOR)
        );

        mock.assertIsSatisfied();
    }

    private Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
        if (oldExchange == null) {
            return newExchange;
        } else {
            Integer n = newExchange.getIn().getBody(Integer.class);
            Integer o = oldExchange.getIn().getBody(Integer.class);
            Integer v = (o == null ? 0 : o) + (n == null ? 0 : n);

            oldExchange.getIn().setBody(v, Integer.class);

            return oldExchange;
        }
    }

    @Override
    protected RoutesBuilder createRouteBuilder() throws Exception {
        return new RouteBuilder() {
            @Override
            public void configure() throws Exception {
                from(ENDPOINT_DIRECT)
                    .routeId("AggregatingRouteOne")
                    .aggregate(header(CORRELATOR))
                    .aggregationRepository(createAggregateRepository())
                    .aggregationStrategy(EhcacheAggregationRepositoryRoutesTest.this::aggregate)
                    .completionSize(VALUES.length)
                        .to("log:org.apache.camel.component.ehcache.processor.aggregate.level=INFO&showAll=true&mulltiline=true")
                        .to(ENDPOINT_MOCK);
            }
        };
    }

    protected EhcacheAggregationRepository createAggregateRepository() throws Exception {
        CacheManager cacheManager = CacheManagerBuilder.newCacheManager(new XmlConfiguration("ehcache.xml"));
        cacheManager.init();

        EhcacheAggregationRepository repository = new EhcacheAggregationRepository();
        repository.setCacheManager(cacheManager);
        repository.setCacheName("aggregate");

        return repository;
    }
}