Page History

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}

{code}
kestrel://foo
{code}

{code}
kestrel://kserver01/foo
{code}

{code}
kestrel://kserver01:22133,kserver02:22133,kserver03:22133/massive
{code}

{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}

{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. Dependencies

The Kestrel component has the following dependencies:
- {{spymemcached}} 2.5+

h4. spymemcached
You *must* have the {{spymemcached}} jar on your classpath.  Here is a snippet you can 

from("kestrel://kserver02:22133/massive?concurrentConsumers=10&waitTimeMs=500")
  .bean("myConsumer", "onMessage");

public class MyConsumer {
    public void onMessage(String message) {
        ...
    }
}

public class MyProducer {
    @EndpointInject(uri = "kestrel://kserver01:22133,kserver02:22133/myqueue")
    ProducerTemplate producerTemplate;

    public void produceSomething() {
        producerTemplate.sendBody("Hello, world.");
    }
}

  <camelContext xmlns="http://camel.apache.org/schema/spring">
    <route>
      <from uri="kestrel://ks01:22133/sequential?concurrentConsumers=1&waitTimeMs=500"/>
      <bean ref="myBean" method="onMessage"/>
    </route>
    <route>
      <from uri="direct:start"/>
      <to uri="kestrel://ks02:22133/stuff"/>
    </route>
  </camelContext>

public class MyBean {
    public void onMessage(String message) {
        ...
    }
}

use in your pom.xml:
{code}
<dependency>
  <groupId>spy</groupId>
  <artifactId>memcached</artifactId>
  <version>2.5</version>
</dependency>
{code}

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, 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 for details.