THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
Wiki Markup |
---|
h2. Kestrel Component The Kestrel component allows messages to be sent to a [Kestrel|https://github.com/robey/kestrel] queue, or messages to be consumed from a Kestrel queue. This component uses the [spymemcached|http://code.google.com/p/spymemcached/] client for memcached protocol communication with Kestrel servers. h3. URI format {code} kestrel://[addresslist/]queuename[?options] {code} Where *queuename* is the name of the queue on Kestrel. The *addresslist* part of the URI may include one or more {{host:port}} pairs. For example, to connect to the queue {{foo}} on {{kserver01:22133}}, use: {code} kestrel://kserver01:22133/foo {code} If the addresslist is omitted, {{localhost:22133}} is assumed, i.e.: {code} kestrel://foo {code} Likewise, if a port is omitted from a {{host:port}} pair in addresslist, the default port 22133 is assumed, i.e.: {code} kestrel://kserver01/foo {code} Here is an example of a Kestrel endpoint URI used for producing to a clustered queue: {code} kestrel://kserver01:22133,kserver02:22133,kserver03:22133/massive {code} Here is an example of a Kestrel endpoint URI used for consuming concurrently from a queue: {code} kestrel://kserver03:22133/massive?concurrentConsumers=25&waitTimeMs=500 {code} h3. Options You can configure properties on each Kestrel endpoint individually by specifying them in the {{?parameters}} portion of the endpoint URI. Any {{?parameters}} that are omitted will default to what is configured on the KestrelComponent's base KestrelConfiguration. The following properties may be set on KestrelConfiguration and/or each individual endpoint: {div:class=confluenceTableSmall} || Option || Default Value || Description || | {{concurrentConsumers}} | {{1}} | Specifies the number of concurrent consumer threads. | | {{waitTimeMs}} | {{100}} | Specifies the {{/t=...}} wait time passed to Kestrel on GET requests. | {div} *NOTE:* If *waitTimeMs* is set to zero (or negative), the {{/t=...}} specifier does *not* get passed to the server on GET requests. When a queue is empty, the GET call returns immediately with no value. In order to prevent "tight looping" in the polling phase, this component will do a {{Thread.sleep(100)}} whenever nothing is returned from the GET request (only when nothing is returned). You are *highly encouraged* to configure a positive non-zero value for waitTimeMs. h3. Configuring the Kestrel component using Spring XML The simplest form of explicit configuration is as follows: {code:xml} <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd"> <bean id="kestrel" class="org.apache.camel.component.kestrel.KestrelComponent"/> <camelContext xmlns="http://camel.apache.org/schema/spring"> </camelContext> </beans> {code} That will enable the Kestrel component with all default settings, i.e. it will use {{localhost:22133}}, 100ms wait time, and a single non-concurrent consumer by default. To use specific options in the base configuration (which supplies configuration to endpoints whose {{?properties}} are not specified), you can set up a KestrelConfiguration POJO as follows: {code:xml} <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd"> <bean id="kestrelConfiguration" class="org.apache.camel.component.kestrel.KestrelConfiguration"> <property name="addresses" value="kestrel01:22133"/> <property name="waitTimeMs" value="100"/> <property name="concurrentConsumers" value="1"/> </bean> <bean id="kestrel" class="org.apache.camel.component.kestrel.KestrelComponent"> <property name="configuration" ref="kestrelConfiguration"/> </bean> <camelContext xmlns="http://camel.apache.org/schema/spring"> </camelContext> </beans> {code} h3. Usage Examples h4. Example 1: Consuming {code} from("kestrel://kserver02:22133/massive?concurrentConsumers=10&waitTimeMs=500") .bean("myConsumer", "onMessage"); {code} {code} public class MyConsumer { public void onMessage(String message) { ... } } {code} h4. Example 2: Producing {code} public class MyProducer { @EndpointInject(uri = "kestrel://kserver01:22133,kserver02:22133/myqueue") ProducerTemplate producerTemplate; public void produceSomething() { producerTemplate.sendBody("Hello, world."); } } {code} h4. Example 3: Spring XML Configuration {code:xml} <camelContext xmlns="http://camel.apache.org/schema/spring"> <route> <from uri="kestrel://ks01:22133/sequential?concurrentConsumers=1&waitTimeMs=500"/> <to uri="log:something<bean ref="myBean" method="onMessage"/> </route> <route> <from uri="direct:start"/> <to uri="kestrel://ks02:22133/stuff"/> </route> </camelContext> {code} {code} public class MyBean { public void onMessage(String message) { ... } } {code} h3. Dependencies The Kestrel component has the following dependencies: - {{spymemcached}} 2.5 (or greater) h4. spymemcached You *must* have the {{spymemcached}} jar on your classpath. Here is a snippet you can use in your pom.xml: {code} <dependency> <groupId>spy</groupId> <artifactId>memcached</artifactId> <version>2.5</version> </dependency> {code} Alternatively, you can [download the jar|http://code.google.com/p/spymemcached/downloads/list] directly. {warning:title=Limitations} *NOTE:* The spymemcached client library does *not* work properly with kestrel when JVM assertions are enabled. There is a known issue with spymemcached when assertions are enabled and a requested key contains the {{/t=...}} extension (i.e. if you're using the {{waitTimeMs}} option on an endpoint URI, which is highly encouraged). Fortunately, JVM assertions are *disabled by default*, unless you [explicitly enable them|http://download.oracle.com/javase/1.4.2/docs/guide/lang/assert.html], so this should not present a problem under normal circumstances. Something to note is that Maven's Surefire test plugin *enables* assertions. If you're using this component in a Maven test environment, you may need to set {{enableAssertions}} to {{false}}. Please refer to the [surefire:test reference|http://maven.apache.org/plugins/maven-surefire-plugin/test-mojo.html] for details. {warning} {include:Endpoint See Also} |