我已经成功地使用 mod_proxy 为示例应用程序配置了集群，但是当我将此集群用于 JSF 应用程序时，我得到了不可序列化的异常：
java.lang.IllegalArgumentException: setAttribute: Non-serializable attribute ErrorDisplay
at org.apache.catalina.session.StandardSession.setAttribute(StandardSession.java:1351)
at org.apache.catalina.ha.session.DeltaSession.setAttribute(DeltaSession.java:647)
at org.apache.catalina.ha.session.DeltaSession.setAttribute(DeltaSession.java:631)
at org.apache.catalina.session.StandardSessionFacade.putValue(StandardSessionFacade.java:135)
at com.avanza.unison.config.ApplicationRequestFilter.activityLoggingAspect(ApplicationRequestFilter.java:365)
at com.avanza.unison.config.ApplicationRequestFilter.sessionDataAspect(ApplicationRequestFilter.java:317)
at com.avanza.unison.config.ApplicationRequestFilter.transactionAspect(ApplicationRequestFilter.java:272)
at com.avanza.unison.config.ApplicationRequestFilter.validURLForUser(ApplicationRequestFilter.java:244)
at com.avanza.unison.config.ApplicationRequestFilter.authenticationAspect(ApplicationRequestFilter.java:217)
at com.avanza.unison.config.ApplicationRequestFilter.licenseAuthentication(ApplicationRequestFilter.java:131)
at com.avanza.unison.config.ApplicationRequestFilter.doFilter(ApplicationRequestFilter.java:113)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.avanza.unison.config.DataReloadFilter.doFilter(DataReloadFilter.java:42)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.avanza.unison.config.ApplicationRequestFilter.activityLoggingAspect(ApplicationRequestFilter.java:341)
at com.avanza.unison.config.ApplicationRequestFilter.sessionDataAspect(ApplicationRequestFilter.java:317)
at com.avanza.unison.config.ApplicationRequestFilter.transactionAspect(ApplicationRequestFilter.java:272)
at com.avanza.unison.config.ApplicationRequestFilter.validURLForUser(ApplicationRequestFilter.java:244)
at com.avanza.unison.config.ApplicationRequestFilter.authenticationAspect(ApplicationRequestFilter.java:217)
at com.avanza.unison.config.ApplicationRequestFilter.licenseAuthentication(ApplicationRequestFilter.java:131)
at com.avanza.unison.config.ApplicationRequestFilter.doFilter(ApplicationRequestFilter.java:113)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.ha.session.JvmRouteBinderValve.invoke(JvmRouteBinderValve.java:227)
at org.apache.catalina.ha.tcp.ReplicationValve.invoke(ReplicationValve.java:347)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:776)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:705)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:898)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
at java.lang.Thread.run(Thread.java:619)
将集群用于 JSF 应用程序是否有任何限制？作为例外指出一些不可序列化的类，我怎样才能使其可序列化。
May 2, 2012 1:31:09 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet Faces Servlet threw exception
java.lang.IllegalArgumentException: setAttribute: Non-serializable attribute ErrorDisplay
at org.apache.catalina.session.StandardSession.setAttribute(StandardSession.java:1351)
at org.apache.catalina.ha.session.DeltaSession.setAttribute(DeltaSession.java:647)
at org.apache.catalina.ha.session.DeltaSession.setAttribute(DeltaSession.java:631)
at org.apache.catalina.session.StandardSessionFacade.putValue(StandardSessionFacade.java:135)
at com.avanza.unison.config.ApplicationRequestFilter.activityLoggingAspect(ApplicationRequestFilter.java:365)
at com.avanza.unison.config.ApplicationRequestFilter.sessionDataAspect(ApplicationRequestFilter.java:317)
at com.avanza.unison.config.ApplicationRequestFilter.transactionAspect(ApplicationRequestFilter.java:272)
at com.avanza.unison.config.ApplicationRequestFilter.validURLForUser(ApplicationRequestFilter.java:244)
at com.avanza.unison.config.ApplicationRequestFilter.authenticationAspect(ApplicationRequestFilter.java:217)
at com.avanza.unison.config.ApplicationRequestFilter.licenseAuthentication(ApplicationRequestFilter.java:131)
at com.avanza.unison.config.ApplicationRequestFilter.doFilter(ApplicationRequestFilter.java:113)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.ha.session.JvmRouteBinderValve.invoke(JvmRouteBinderValve.java:227)
at org.apache.catalina.ha.tcp.ReplicationValve.invoke(ReplicationValve.java:347)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:776)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:705)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:898)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
at java.lang.Thread.run(Thread.java:619)