Ehcache
Since Camel 2.18
Both producer and consumer are supported
The Ehcache component enables you to perform caching operations using Ehcache 3 as the Cache Implementation.
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>Configuring Options
Camel components are configured on two separate levels:
-
component level
-
endpoint level
Configuring Component Options
The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.
Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.
Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.
Configuring Endpoint Options
Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.
Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL as a type safe way of configuring endpoints.
A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.
The following two sections lists all the options, firstly for the component followed by the endpoint.
Component Options
The Ehcache component supports 16 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
The cache manager. |
CacheManager |
||
The cache manager configuration. |
Configuration |
||
URI pointing to the Ehcache XML configuration file’s location. |
String |
||
Configure if a cache need to be created if it does exist or can’t be pre-configured. |
true |
boolean |
|
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 |
|
Set the delivery mode (synchronous, asynchronous). Enum values:
|
ASYNCHRONOUS |
EventFiring |
|
Set the delivery mode (ordered, unordered). Enum values:
|
ORDERED |
EventOrdering |
|
Set the type of events to listen for (EVICTED,EXPIRED,REMOVED,CREATED,UPDATED). You can specify multiple entries separated by comma. Enum values:
|
String |
||
To configure the default cache action. If an action is set in the message header, then the operation from the header takes precedence. |
String |
||
To configure the default action key. If a key is set in the message header, then the key from the header takes precedence. |
Object |
||
Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. |
false |
boolean |
|
Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. |
true |
boolean |
|
The default cache configuration to be used to create caches. |
CacheConfiguration |
||
A map of cache configuration to be used to create caches. |
Map |
||
The cache key type, default java.lang.Object. |
String |
||
The cache value type, default java.lang.Object. |
String |
Endpoint Options
The Ehcache endpoint is configured using URI syntax:
ehcache:cacheName
with the following path and query parameters:
Query Parameters (17 parameters)
| Name | Description | Default | Type |
|---|---|---|---|
The cache manager. |
CacheManager |
||
The cache manager configuration. |
Configuration |
||
URI pointing to the Ehcache XML configuration file’s location. |
String |
||
Configure if a cache need to be created if it does exist or can’t be pre-configured. |
true |
boolean |
|
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 |
|
Set the delivery mode (synchronous, asynchronous). Enum values:
|
ASYNCHRONOUS |
EventFiring |
|
Set the delivery mode (ordered, unordered). Enum values:
|
ORDERED |
EventOrdering |
|
Set the type of events to listen for (EVICTED,EXPIRED,REMOVED,CREATED,UPDATED). You can specify multiple entries separated by comma. Enum values:
|
String |
||
To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored. |
ExceptionHandler |
||
Sets the exchange pattern when the consumer creates an exchange. Enum values:
|
ExchangePattern |
||
To configure the default cache action. If an action is set in the message header, then the operation from the header takes precedence. |
String |
||
To configure the default action key. If a key is set in the message header, then the key from the header takes precedence. |
Object |
||
Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. |
false |
boolean |
|
The default cache configuration to be used to create caches. |
CacheConfiguration |
||
A map of cache configuration to be used to create caches. |
Map |
||
The cache key type, default java.lang.Object. |
String |
||
The cache value type, default java.lang.Object. |
String |
Message Headers
The Ehcache component supports 8 message header(s), which is/are listed below:
| Name | Description | Default | Type |
|---|---|---|---|
|
Constant: |
The operation to be performed on the cache, valid options are: CLEAR PUT PUT_ALL PUT_IF_ABSENT GET GET_ALL REMOVE REMOVE_ALL REPLACE. |
String |
|
CamelEhcacheActionHasResult (common) Constant: |
Set to true if the action has a result. |
Boolean |
|
CamelEhcacheActionSucceeded (common) Constant: |
Set to true if the action was successful. |
Boolean |
|
|
Constant: |
The cache key used for an action. |
Object |
|
|
Constant: |
A list of keys, used in PUT_ALL GET_ALL REMOVE_ALL. |
Set |
|
|
Constant: |
The value to put in the cache or the result of an operation. |
Object |
|
|
Constant: |
The old value associated to a key for actions like PUT_IF_ABSENT or the Object used for comparison for actions like REPLACE. |
Object |
|
CamelEhcacheEventType (common) Constant: |
The type of event received. |
EventType |
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");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(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;
}
}Spring Boot Auto-Configuration
When using ehcache with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:
<dependency>
<groupId>org.apache.camel.springboot</groupId>
<artifactId>camel-ehcache-starter</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>The component supports 21 options, which are listed below.