Available as of Apache 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, used the processors defined for the cache component.
cache://cacheName[?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
The available options are:
Name | Default Value | Description |
---|---|---|
maxElementsInMemory
|
1000
|
The numer of elements that may be stored in the defined cache |
memoryStoreEvictionPolicy
|
MemoryStoreEvictionPolicy.LFU
|
The number of elements that may be stored in the defined cache. The policy options include:
|
overflowToDisk
|
true
|
Specifies whether cache may overflow to disk. |
eternal
|
false
|
Sets whether elements are eternal. If eternal, timeouts are ignored and the element is never expired. |
timeToLiveSeconds
|
300
|
The maximum time between creation time and when an element expires. Is only used if the element is not eternal. |
timeToIdleSeconds
|
300
|
The maximum amount of time between accesses before an element expires. |
diskPersistent
|
true
|
Whether the disk store persists between restarts of the
Virtual Machine. The default value is
false . |
diskExpiryThreadIntervalSeconds
|
120
|
The number of seconds between runs of the disk expiry thread. The default value is 120 seconds. |
cacheManagerFactory
|
null
|
Apache Camel 2.3: If you
want to use a custom factory which instantiates and creates
the EHCache net.sf.ehcache.CacheManager . |
Header | Description |
---|---|
CACHE_OPERATION
|
The operation to be performed on the cache. The valid options are:
|
CACHE_KEY
|
The cache key used to store the message in the cache. The
cache key is optional, if the CACHE_OPERATION
is DELETEALL . |
Sending 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 - setting the Message Exchange Headers shown above. - ensuring that the Message Exchange Body contains the message directed to the cache
Receiving 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
ADD
/UPDATE
/DELETE
/DELETEALL
).
Upon such an activity taking place - an exchange containing Message
Exchange Headers and a Message Exchange Body containing the just
added/updated payload is placed and sent. - in case of a
DELETEALL
operation, the Message Exchange Header
CACHE_KEY
and the Message Exchange Body are not
populated.
There are a set of nice processors with the ability to perform cache lookups and selectively replace payload content at the - body - token - xpath level
from("cache://MyApplicationCache" + "?maxElementsInMemory=1000" + "&memoryStoreEvictionPolicy=" + "MemoryStoreEvictionPolicy.LFU" + "&overflowToDisk=true" + "&eternal=true" + "&timeToLiveSeconds=300" + "&timeToIdleSeconds=true" + "&diskPersistent=true" + "&diskExpiryThreadIntervalSeconds=300")
RouteBuilder builder = new RouteBuilder() { public void configure() { from("direct:start") .setHeader("CACHE_OPERATION", constant("ADD")) .setHeader("CACHE_KEY", constant("Ralph_Waldo_Emerson")) .to("cache://TestCache1") } };
RouteBuilder builder = new RouteBuilder() { public void configure() { from("direct:start") .setHeader("CACHE_OPERATION", constant("UPDATE")) .setHeader("CACHE_KEY", constant("Ralph_Waldo_Emerson")) .to("cache://TestCache1") } };
RouteBuilder builder = new RouteBuilder() { public void configure() { from("direct:start") .setHeader("CACHE_OPERATION", constant("DELETE")) .setHeader("CACHE_KEY", constant("Ralph_Waldo_Emerson")) .to("cache://TestCache1") } };
RouteBuilder builder = new RouteBuilder() { public void configure() { from("direct:start") .setHeader("CACHE_OPERATION", constant("DELETEALL")) .to("cache://TestCache1"); } };
RouteBuilder 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("CACHE_OPERATION"); String key = (String) exchange.getIn().getHeader("CACHE_KEY"); Object body = exchange.getIn().getBody(); // Do something } }) } };
RouteBuilder builder = new RouteBuilder() { public void configure() { //Message Body Replacer from("cache://TestCache1") .filter(header("CACHE_KEY").isEqualTo("greeting")) .process(new CacheBasedMessageBodyReplacer("cache://TestCache1","farewell")) .to("direct:next"); //Message Token replacer from("cache://TestCache1") .filter(header("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("CACHE_KEY").isEqualTo("XML_FRAGMENT")) .process(new CacheBasedXPathReplacer("cache://TestCache1","book1","/books/book1")) .process (new CacheBasedXPathReplacer("cache://TestCache1","book2","/books/book2")) .to("direct:next"); } };
from("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");
Note: CHECK command tests existence of the entry in the cache but doesn't place message to 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();
EHCache 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.