activemq networks

当有多个broker时，如果某个broker上没有consumers，那么这个broker上的消息可能会因得不到处理而积压起来。目前的解决方案是使用Networkof brokers，以便在broker之间存储转发消息。

两种方式：

第一种

broker 1:

<?xml version="1.0" encoding="UTF-8"?>
 	<!--
 	Licensed to the Apache Software Foundation (ASF) under one or more
 	contributor license agreements. See the NOTICE file distributed with
 	this work for additional information regarding copyright ownership.
 	The ASF licenses this file to You under the Apache License, Version 2.0
 	(the "License"); you may not use this file except in compliance with
 	the License. You may obtain a copy of the License at 	
 	http://www.apache.org/licenses/LICENSE-2.0 	
 	Unless required by applicable law or agreed to in writing, software
 	distributed under the License is distributed on an "AS IS" BASIS,
 	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 	See the License for the specific language governing permissions and
 	limitations under the License.
 	-->
 	<beans
 	xmlns="http://www.springframework.org/schema/beans"
 	xmlns:amq="http://activemq.apache.org/schema/core"
 	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-2.0.xsd
 	http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core.xsd">
 	
 	<broker brokerName="broker1" persistent="false" useJmx="false" xmlns="http://activemq.apache.org/schema/core">
 	
    <networkConnectors>
      <networkConnector uri="multicast://default"/>
    </networkConnectors>
 	
 	<persistenceAdapter>
 	<memoryPersistenceAdapter/>
 	</persistenceAdapter>
 	
  <transportConnectors>
      <transportConnector uri="tcp://localhost:0" discoveryUri="multicast://default"/>
    </transportConnectors>
 	
 	</broker>
 	
 	</beans>

broker 2:

<!--
    Licensed to the Apache Software Foundation (ASF) under one or more
    contributor license agreements.  See the NOTICE file distributed with
    this work for additional information regarding copyright ownership.
    The ASF licenses this file to You under the Apache License, Version 2.0
    (the "License"); you may not use this file except in compliance with
    the License.  You may obtain a copy of the License at
   
    http://www.apache.org/licenses/LICENSE-2.0
   
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
-->
<!-- START SNIPPET: example -->
<beans
  xmlns="http://www.springframework.org/schema/beans"
  xmlns:amq="http://activemq.apache.org/schema/core"
  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-2.0.xsd
  http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core.xsd">

    <!-- Allows us to use system properties as variables in this configuration file -->
    <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <value>file:${activemq.base}/conf/credentials.properties</value>
        </property>      
    </bean>
 <bean id="securityConstraint" class="org.eclipse.jetty.http.security.Constraint">
  <property name="name" value="BASIC" />
  <property name="roles" value="admin" />
  <property name="authenticate" value="true" /> 
 </bean>
    <!-- 
        The <broker> element is used to configure the ActiveMQ broker. 
    -->
    <broker xmlns="http://activemq.apache.org/schema/core" brokerName="broker2" dataDirectory="${activemq.base}/data" destroyApplicationContextOnStop="true">
          
        <destinationPolicy>
            <policyMap>
              <policyEntries>
                <policyEntry topic=">" producerFlowControl="true" memoryLimit="1mb">
                  <pendingSubscriberPolicy>
                    <vmCursor />
                  </pendingSubscriberPolicy>
                </policyEntry>
                <policyEntry queue=">" producerFlowControl="true" memoryLimit="1mb">
                  <!-- Use VM cursor for better latency
                       For more information, see:
                       
                       http://activemq.apache.org/message-cursors.html
                       
                  <pendingQueuePolicy>
                    <vmQueueCursor/>
                  </pendingQueuePolicy>
                  -->
                </policyEntry>
              </policyEntries>
            </policyMap>
        </destinationPolicy> 
 
 
    <networkConnectors>
      <networkConnector uri="multicast://default"/>
    </networkConnectors>
 	
 	<persistenceAdapter>
		<memoryPersistenceAdapter/>
 	</persistenceAdapter>
 	
   <transportConnectors>
      <transportConnector uri="tcp://localhost:0" discoveryUri="multicast://default"/>
    </transportConnectors>

    </broker>

    <!-- 
        Enable web consoles, REST and Ajax APIs and demos
        It also includes Camel (with its web console), see ${ACTIVEMQ_HOME}/conf/camel.xml for more info
        
        Take a look at ${ACTIVEMQ_HOME}/conf/jetty.xml for more details 
    -->
  
    
</beans>
<!-- END SNIPPET: example -->

第二种： multicast discovery

  <broker name="sender" persistent="false" useJmx="false">  
    <networkConnectors>
      <networkConnector uri="multicast://default"/>
    </networkConnectors>

    <persistenceAdapter>
      <memoryPersistenceAdapter/>
    </persistenceAdapter>

  <transportConnectors>
      <transportConnector uri="tcp://localhost:0" discoveryUri="multicast://default"/>
    </transportConnectors>
  </broker>

深入研究需参看文档

相关文章： http://blog.youkuaiyun.com/leisore/article/details/6221788