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Cache ComponentThis component is deprecated. As of Camel 2.18.0 You should use Ehcache. Available as of Camel 2.1 The cache component enables you to perform caching operations using EHCache as the Cache Implementation. The cache itself is created on demand or if a cache of that name already exists then it is simply utilized with its original settings. 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. If you need to perform selections from a pre-existing cache, use the processors defined for the cache component. Maven users will need to add the following dependency to their <dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-cache</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>
URI formatcache://cacheName[?options] You can append query options to the URI in the following format, Options
Cache Component options
Sending/Receiving Messages to/from the cacheMessage Headers up to Camel 2.7
Message Headers Camel 2.8+Header changes in Camel 2.8 The header names and supported values have changed to be prefixed with 'CamelCache' and use mixed case. This makes them easier to identify and keep separate from other headers. The CacheConstants variable names remain unchanged, just their values have been changed. Also, these headers are now removed from the exchange after the cache operation is performed.
The
Cache ProducerSending data to the cache involves the ability to direct payloads in exchanges to be stored in a pre-existing or created-on-demand cache. The mechanics of doing this involve
Cache ConsumerReceiving data from the cache involves the ability of the CacheConsumer to listen on a pre-existing or created-on-demand Cache using an event Listener and receive automatic notifications when any cache activity take place (i.e CamelCacheGet/CamelCacheUpdate/CamelCacheDelete/CamelCacheDeleteAll). Upon such an activity taking place
Cache ProcessorsThere are a set of nice processors with the ability to perform cache lookups and selectively replace payload content at the
Cache Usage SamplesExample 1: Configuring the cachefrom("cache://MyApplicationCache" +
"?maxElementsInMemory=1000" +
"&memoryStoreEvictionPolicy=" +
"MemoryStoreEvictionPolicy.LFU" +
"&overflowToDisk=true" +
"&eternal=true" +
"&timeToLiveSeconds=300" +
"&timeToIdleSeconds=true" +
"&diskPersistent=true" +
"&diskExpiryThreadIntervalSeconds=300")
Example 2: Adding keys to the cacheRouteBuilder builder = new RouteBuilder() {
public void configure() {
from("direct:start")
.setHeader(CacheConstants.CACHE_OPERATION, constant(CacheConstants.CACHE_OPERATION_ADD))
.setHeader(CacheConstants.CACHE_KEY, constant("Ralph_Waldo_Emerson"))
.to("cache://TestCache1")
}
};
Example 2: Updating existing keys in a cacheRouteBuilder builder = new RouteBuilder() {
public void configure() {
from("direct:start")
.setHeader(CacheConstants.CACHE_OPERATION, constant(CacheConstants.CACHE_OPERATION_UPDATE))
.setHeader(CacheConstants.CACHE_KEY, constant("Ralph_Waldo_Emerson"))
.to("cache://TestCache1")
}
};
Example 3: Deleting existing keys in a cacheRouteBuilder builder = new RouteBuilder() {
public void configure() {
from("direct:start")
.setHeader(CacheConstants.CACHE_OPERATION, constant(CacheConstants.CACHE_DELETE))
.setHeader(CacheConstants.CACHE_KEY", constant("Ralph_Waldo_Emerson"))
.to("cache://TestCache1")
}
};
Example 4: Deleting all existing keys in a cacheRouteBuilder builder = new RouteBuilder() {
public void configure() {
from("direct:start")
.setHeader(CacheConstants.CACHE_OPERATION, constant(CacheConstants.CACHE_DELETEALL))
.to("cache://TestCache1");
}
};
Example 5: Notifying any changes registering in a Cache to Processors and other ProducersRouteBuilder builder = new RouteBuilder() {
public void configure() {
from("cache://TestCache1")
.process(new Processor() {
public void process(Exchange exchange)
throws Exception {
String operation = (String) exchange.getIn().getHeader(CacheConstants.CACHE_OPERATION);
String key = (String) exchange.getIn().getHeader(CacheConstants.CACHE_KEY);
Object body = exchange.getIn().getBody();
// Do something
}
})
}
};
Example 6: Using Processors to selectively replace payload with cache valuesRouteBuilder builder = new RouteBuilder() {
public void configure() {
//Message Body Replacer
from("cache://TestCache1")
.filter(header(CacheConstants.CACHE_KEY).isEqualTo("greeting"))
.process(new CacheBasedMessageBodyReplacer("cache://TestCache1","farewell"))
.to("direct:next");
//Message Token replacer
from("cache://TestCache1")
.filter(header(CacheConstants.CACHE_KEY).isEqualTo("quote"))
.process(new CacheBasedTokenReplacer("cache://TestCache1","novel","#novel#"))
.process(new CacheBasedTokenReplacer("cache://TestCache1","author","#author#"))
.process(new CacheBasedTokenReplacer("cache://TestCache1","number","#number#"))
.to("direct:next");
//Message XPath replacer
from("cache://TestCache1").
.filter(header(CacheConstants.CACHE_KEY).isEqualTo("XML_FRAGMENT"))
.process(new CacheBasedXPathReplacer("cache://TestCache1","book1","/books/book1"))
.process (new CacheBasedXPathReplacer("cache://TestCache1","book2","/books/book2"))
.to("direct:next");
}
};
Example 7: Getting an entry from the Cachefrom("direct:start")
// Prepare headers
.setHeader(CacheConstants.CACHE_OPERATION, constant(CacheConstants.CACHE_OPERATION_GET))
.setHeader(CacheConstants.CACHE_KEY, constant("Ralph_Waldo_Emerson")).
.to("cache://TestCache1").
// Check if entry was not found
.choice().when(header(CacheConstants.CACHE_ELEMENT_WAS_FOUND).isNull()).
// If not found, get the payload and put it to cache
.to("cxf:bean:someHeavyweightOperation").
.setHeader(CacheConstants.CACHE_OPERATION, constant(CacheConstants.CACHE_OPERATION_ADD))
.setHeader(CacheConstants.CACHE_KEY, constant("Ralph_Waldo_Emerson"))
.to("cache://TestCache1")
.end()
.to("direct:nextPhase");
Example 8: Checking for an entry in the CacheNote: The CHECK command tests existence of an entry in the cache but doesn't place a message in the body. from("direct:start")
// Prepare headers
.setHeader(CacheConstants.CACHE_OPERATION, constant(CacheConstants.CACHE_OPERATION_CHECK))
.setHeader(CacheConstants.CACHE_KEY, constant("Ralph_Waldo_Emerson")).
.to("cache://TestCache1").
// Check if entry was not found
.choice().when(header(CacheConstants.CACHE_ELEMENT_WAS_FOUND).isNull()).
// If not found, get the payload and put it to cache
.to("cxf:bean:someHeavyweightOperation").
.setHeader(CacheConstants.CACHE_OPERATION, constant(CacheConstants.CACHE_OPERATION_ADD))
.setHeader(CacheConstants.CACHE_KEY, constant("Ralph_Waldo_Emerson"))
.to("cache://TestCache1")
.end();
Management of EHCacheEHCache has its own statistics and management from JMX. Here's a snippet on how to expose them via JMX in a Spring application context: <bean id="ehCacheManagementService" class="net.sf.ehcache.management.ManagementService" init-method="init" lazy-init="false">
<constructor-arg>
<bean class="net.sf.ehcache.CacheManager" factory-method="getInstance"/>
</constructor-arg>
<constructor-arg>
<bean class="org.springframework.jmx.support.JmxUtils" factory-method="locateMBeanServer"/>
</constructor-arg>
<constructor-arg value="true"/>
<constructor-arg value="true"/>
<constructor-arg value="true"/>
<constructor-arg value="true"/>
</bean>
Of course you can do the same thing in straight Java: ManagementService.registerMBeans(CacheManager.getInstance(), mbeanServer, true, true, true, true); You can get cache hits, misses, in-memory hits, disk hits, size stats this way. You can also change CacheConfiguration parameters on the fly. Cache replication Camel 2.8+The Camel Cache component is able to distribute a cache across server nodes using several different replication mechanisms including: RMI, JGroups, JMS and Cache Server. There are two different ways to make it work: 1. You can configure OR 2. You can configure these three options:
Configuring Camel Cache replication using the first option is a bit of hard work as you have to configure all caches separately. So in a situation when the all names of caches are not known, using The second option is much better when you want to use many different caches as you do not need to define options per cache. This is because replication options are set per It might be useful to read the EHCache manual to get a better understanding of the Camel Cache replication mechanism. Example: JMS cache replicationJMS replication is the most powerful and secured replication method. Used together with Camel Cache replication makes it also rather simple. |
