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The Kestrel component allows messages to be sent to a Kestrel queue, or messages to be consumed from a Kestrel queue. This component uses the spymemcached client for memcached protocol communication with Kestrel servers.

Warning

The kestrel project is inactive and the Camel team regard this components as deprecated.

 

URI format

Code Block

kestrel://[addresslist/]queuename[?options]

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 Block

kestrel://kserver01:22133/foo

If the addresslist is omitted, localhost:22133 is assumed, i.e.:

Code Block

kestrel://foo

Likewise, if a port is omitted from a host:port pair in addresslist, the default port 22133 is assumed, i.e.:

Code Block

kestrel://kserver01/foo

Here is an example of a Kestrel endpoint URI used for producing to a clustered queue:

Code Block

kestrel://kserver01:22133,kserver02:22133,kserver03:22133/massive

Here is an example of a Kestrel endpoint URI used for consuming concurrently from a queue:

Code Block

kestrel://kserver03:22133/massive?concurrentConsumers=25&waitTimeMs=500

...

The simplest form of explicit configuration is as follows:

Code Block
xml
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>

...

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 Block
xml
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>

...

Example 1: Consuming

Code Block

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

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

Example 2: Producing

Code Block

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

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

Example 3: Spring XML Configuration

Code Block
xml
xml

  <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>
Code Block

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

...

You must have the spymemcached jar on your classpath. Here is a snippet you can use in your pom.xml:

Code Block

<dependency>
  <groupId>spy</groupId>
  <artifactId>memcached</artifactId>
  <version>2.5</version>
</dependency>

...

Warning
titleLimitations

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.

Include Page
Endpoint See Also
Endpoint See Also