Chapter 84. Kestrel

Kestrel Component
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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 this component is therefore deprecated.

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

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

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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:

kestrel://kserver01:22133/foo

kestrel://kserver01:22133/foo

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

kestrel://foo

kestrel://foo

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

kestrel://kserver01/foo

kestrel://kserver01/foo

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

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

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

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

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

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

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Options
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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:

Expand

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.

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.

Configuring the Kestrel component using Spring XML
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The simplest form of explicit configuration is as follows:

<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>

<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>

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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:

<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>

<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>

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Usage Examples
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Example 1: Consuming
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from("kestrel://kserver02:22133/massive?concurrentConsumers=10&waitTimeMs=500")
  .bean("myConsumer", "onMessage");

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

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

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

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Example 2: Producing
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public class MyProducer {
    @EndpointInject(uri = "kestrel://kserver01:22133,kserver02:22133/myqueue")
    ProducerTemplate producerTemplate;

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

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

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

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Example 3: Spring XML Configuration
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  <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>

  <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>

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

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

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Dependencies
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The Kestrel component has the following dependencies:

spymemcached 2.5 (or greater)

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

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

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

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Alternatively, you can download the jar directly.

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, 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.

이 콘텐츠는 선택한 언어로 제공되지 않습니다.

Kestrel Component
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URI format
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Options
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Configuring the Kestrel component using Spring XML
링크 복사

Usage Examples
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Example 1: Consuming
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Example 2: Producing
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Example 3: Spring XML Configuration
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Dependencies
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spymemcached
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이 콘텐츠는 선택한 언어로 제공되지 않습니다.

Chapter 84. Kestrel

Kestrel Component링크 복사링크가 클립보드에 복사되었습니다!

URI format링크 복사링크가 클립보드에 복사되었습니다!

Options링크 복사링크가 클립보드에 복사되었습니다!

Configuring the Kestrel component using Spring XML링크 복사링크가 클립보드에 복사되었습니다!

Usage Examples링크 복사링크가 클립보드에 복사되었습니다!

Example 1: Consuming링크 복사링크가 클립보드에 복사되었습니다!

Example 2: Producing링크 복사링크가 클립보드에 복사되었습니다!

Example 3: Spring XML Configuration링크 복사링크가 클립보드에 복사되었습니다!

Dependencies링크 복사링크가 클립보드에 복사되었습니다!

spymemcached링크 복사링크가 클립보드에 복사되었습니다!

자세한 정보

평가판, 구매 및 판매

커뮤니티

Red Hat 문서 정보

보다 포괄적 수용을 위한 오픈 소스 용어 교체

Red Hat 소개

Theme

Red Hat legal and privacy links

Red Hat legal and privacy links

Kestrel Component
링크 복사

URI format
링크 복사

Options
링크 복사

Configuring the Kestrel component using Spring XML
링크 복사

Usage Examples
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Example 1: Consuming
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Example 2: Producing
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Example 3: Spring XML Configuration
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Dependencies
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spymemcached
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