Tomcat 6 多机实现Session复制

session复制
session复制是指tomcat彼此之间通过组播方式将session发到各个tomcat实例上，如果其中一个访问出错，则另外tomcat仍然具有有效的session内容，从而能正常接管其session。坏处是当tomcat实例很多，或者用户在session中有大量操作时，组播发送的信息量十分惊人。

Tomcat的session复制目前有两种类型，他们的配置稍有区别
分别为：org.apache.catalina.ha.session.DeltaManager和org.apache.catalina.ha.session.BackupManager

DeltaManager复制并发送Session数据到集群下所有的节点，这个实现类被证明非常可靠、运行得非常好。不过有个局限性就是集群的节点类型要相同，而且要部署相同的应用程序。

测试环境
Using CATALINA_BASE:   "C:\tomcat_6_1"
Using CATALINA_HOME:   "C:\tomcat_6_1"
Using CATALINA_TMPDIR: "C:\tomcat_6_1\temp"
Using JRE_HOME:        "E:\Program Files\Java\jdk1.6.0_21"
Using CLASSPATH:       "C:\tomcat_6_1\bin\bootstrap.jar"
Server version: Apache Tomcat/6.0.26
JVM Version:    1.6.0_21-b07
JVM Vendor:     Sun Microsystems Inc.


一.DeltaManager
1.<distributable/> 配置
修改${CATALINA_HOME}\conf\web.xml文件，加入标签
<distributable/>
直接加在</web-app>之前
2.修改\conf\server.xml
修改：

<!--
      <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
-->   

为：

<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" channelSendOptions="8">
                <Manager className="org.apache.catalina.ha.session.DeltaManager"  expireSessionsOnShutdown="false" notifyListenersOnReplication="true" />
                <Channel className="org.apache.catalina.tribes.group.GroupChannel">
                        <Membership className="org.apache.catalina.tribes.membership.McastService"  [color=darkred]bind="127.0.0.1"[/color]  address="228.0.0.4" port="45564" frequency="500" dropTime="3000" />
                        <Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver" address="192.168.1.148" port="4005" autoBind="100" selectorTimeout="5000" maxThreads="6" /> 
                        <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">
                                <Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender" />
                        </Sender>
                        <Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector" />
                        <Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor" />
                 </Channel>
 
                <Valve className="org.apache.catalina.ha.tcp.ReplicationValve" filter=".*\.gif|.*\.js|.*\.jpeg|.*\.jpg|.*\.png|.*\.htm|.*\.html|.*\.css|.*\.txt" />
                <Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve" />
                <Deployer className="org.apache.catalina.ha.deploy.FarmWarDeployer" tempDir="/tmp/war-temp/" deployDir="/tmp/war-deploy/" watchDir="/tmp/war-listen/" watchEnabled="false" />  
                <ClusterListener className="org.apache.catalina.ha.session.JvmRouteSessionIDBinderListener" />
                <ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener" />
</Cluster>

二.DeltaManager
1.修改：

<!--
      <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
-->   

为：

<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" channelSendOptions="6"> 
				<Manager className="org.apache.catalina.ha.session.BackupManager"  expireSessionsOnShutdown="false" notifyListenersOnReplication="true" mapSendOptions="6"/> 
				<Channel className="org.apache.catalina.tribes.group.GroupChannel">  
				<Membership className="org.apache.catalina.tribes.membership.McastService" 
                        [color=red] bind="127.0.0.1" [/color]
                         address="228.0.0.4" 
                         port="45564" 
                         frequency="500" 
                         dropTime="3000"/> 
             <Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver" 
                       address="auto" 
                       port="4001" 
                       selectorTimeout="100" 
                       maxThreads="6"/> 
             <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter"> 
               <Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender" timeout="60000"/>  
             </Sender> 
             <Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/> 
             <Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor"/> 
             <Interceptor className="org.apache.catalina.tribes.group.interceptors.ThroughputInterceptor"/> 
           </Channel> 
              <Valve className="org.apache.catalina.ha.tcp.ReplicationValve" 
                  filter=".*\.gif;.*\.js;.*\.jpg;.*\.png;.*\.htm;.*\.html;.*\.css;.*\.txt;"/> 
              <ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/> 
         </Cluster>

2.<distributable/> 配置
修改web应用里面WEB-INF目录下的web.xml文件，加入标签
<distributable/>
直接加在</web-app>之前



三.最后，其他可能操作，开启网卡组播功能：
route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0


参考：
http://wiki.apache.org/tomcat/ClusteringOverview
http://blog.csdn.net/lifetragedy/article/details/7712691