应用版本：
apache：2.2.3
tomcat：7.0.14
配置要点：
1.tomcat session复制：
server.xml,在<Engine>节点下添加:
<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"
address="228.0.0.4" <!-- 此地址不变 -->
port="45564"
frequency="500"
dropTime="3000"/>
<Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"
address="auto"
//tcpListenPort如果是同一机器部署两个tomcat7应用，则修改tomcat7_b为4001，以免冲突. 不同机器下，不用更改此项.
port="4000"
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=""/>
<Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve"/>
// 如果tomcat启动出现：严重: FarmWarDeployer can only work as host cluster subelement! 可以将此节点去掉
<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>
2. 为tomcat增加唯一标示（个人理解），添加jvmRoute属性，apache负载均衡用到
<Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcat7_1">
<Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcat7_2">
3.同一机子上有多个tomcat，SHUTDOWN 端口不能冲突。
tomcat7_1：<Server port="8006" shutdown="SHUTDOWN">
tomcat7_2：<Server port="8007" shutdown="SHUTDOWN">
4.同理，http端口和ajp端口都不能冲突：
eg：
<connector port="8082" protocol="HTTP/1.1" onnectionTimeout="20000" edirectPort="8443" />
<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />
5. 为了方便测试，直接用到了webapps 中的examples工程，
tomcat7_1\webapps\examples\WEB-INF\web.xml中加入<distributable/>
tomcat7_2\webapps\examples\WEB-INF\web.xml中加入<distributable/>
两个tomcat中examples工程都加入test.jsp
代码如下：
<%@ page contentType="text/html; charset=UTF-8" %>
<%@ page import="java.util.*" %>
<html><head><title>Cluster Test</title></head>
<body>
<%
//HttpSession session = request.getSession(true);
System.out.println(session.getId());
out.println("<br> SESSION ID:" + session.getId()+"<br>");
String name = request.getParameter("name");
if (name != null && name.length() > 0) {
String value = request.getParameter("value");
session.setAttribute(name, value);
}
out.print("<b>Session List:</b>");
Enumeration<String> names = session.getAttributeNames();
while (names.hasMoreElements()) {
String sname = names.nextElement();
String value = session.getAttribute(sname).toString();
out.println( sname + " = " + value+"<br>");
System.out.println( sname + " = " + value);
}
%>
<form action="test.jsp" method="post">
session名称:<input type=text size=20 name="name">
<br>
session值:<input type=text size=20 name="value">
<br>
<input type=submit value="提交">
</form>
</body>
</html>
在此，session复制工作完毕，测试：
访问tomcat7_1输入session名称和值提交以后再访问tomcat7_2，如果session列表中有tomcat7_1的名称和值说明session同步工作成功！
6.负载均衡配置：
负载方式有jk和 mod_proxy
jk方式曾经已经做过，本次尝试mod_proxy
配置步骤：
httpd.conf中增加以下模块：
LoadModule proxy_module modules/mod_proxy.so LoadModule proxy_ajp_module modules/mod_proxy_ajp.so LoadModule proxy_balancer_module modules/mod_proxy_balancer.so LoadModule proxy_connect_module modules/mod_proxy_connect.so LoadModule proxy_ftp_module modules/mod_proxy_ftp.so LoadModule proxy_http_module modules/mod_proxy_http.so
再增加：
#虚拟机配置,负载均衡配置
<VirtualHost *:80>
ServerAdmin [email protected]
ServerName localhost
ServerAlias localhost
ProxyPass / balancer://cluster/ stickysession=JSESSIONID|jsessionid nofailover=On
ProxyPassReverse / balancer://cluster/
#ErrorLog "logs/error.log"
#CustomLog "logs/access.log" common
</VirtualHost>
ProxyRequests Off
<proxy balancer://cluster>
BalancerMember ajp://内网ip:8009 loadfactor=1 route=tomcat7_1 smax=5 max=20 ttl=120 retry=300 timeout=15
BalancerMember ajp://内网ip:8010 loadfactor=1 route=tomcat7_2 smax=5 max=20 ttl=120 retry=300 timeout=15
# status=+H为配置热备，当所有机器都over时，才会请求该机器
#BalancerMember http://xxxxxxx:8009 status=+H
#lbmethod=byrequests 按照请求次数均衡(默认)
#lbmethod=bytraffic 按照流量均衡
#lbmethod=bybusyness 按照繁忙程度均衡(总是分配给活跃请求数最少的服务器)
ProxySet lbmethod=bytraffic
</proxy>
配置完毕。将今天的奋战结果记录下来，方便以后参考。好记性不如iteye的博客，
