JSF Servlet异常:当应用程序会话在服务器之间跳转时，没有视图保存状态 [英] JSF Servlet Exception: No view save state when application session jumps between servers

问题描述

我有一个Web应用程序在Liberty服务器上的CICS环境中运行.对于工作负载管理，将应用程序会话设置为在3个不同的服务器之间切换，这在给定会话期间随机发生.实施此操作后，我目前收到以下错误:

I have a web app running on in a CICS environment on Liberty servers. For workload management, the application session is set up to shift between 3 different servers, which occurs randomly during a given session. Implementing this, I am currently receiving the following error:

Error 500: javax.servlet.ServletException: /{page_name}.xhtml - No saved view 
state could be found for the view identifier: /{page_name}.xhtml

该错误是随机发生的，但似乎只有在应用程序会话已跳至另一台服务器时才会发生.我通过关闭两台服务器来验证了这一点，然后发现会话可以正常运行.我的应用程序具有安全性，并且在会话启动时需要登录凭据，并且我认为这在某种程度上会影响它在跳转服务器时影响页面的呈现，就像凭据没有随会话一起跳转一样.我进行了一些研究，并尝试通过将以下上下文参数添加到应用程序web.xml中，将state_saving方法从服务器切换到客户端:

The error happens at random, but it appears that it only occurs when the application session has hopped to a different server. I verified this by shutting down two servers, and saw that a session would run without any problems after that. My application has security and requires login credentials when a session starts, and I believe this is somehow affecting the rendering of pages when it jumps servers, as if the credentials are not jumping with the session. I did some research and attempted to switch the state_saving method from server to client by adding the following context param to the applications web.xml:

<context-param>
    <param-name>javax.faces.STATE_SAVING_METHOD</param-name>        
    <param-value>client</param-value>
</context-param>

不幸的是，问题仍然存在.任何建议将不胜感激.如果需要更多信息或需要更大的堆栈跟踪，请在下面发表评论！

Unfortunately, the issue still persists. Any suggestions would be much appreciated. If any more information or a larger stack trace is needed, please comment below!

堆栈跟踪:

[2/12/19 15:25:53:672 CST] 00000056 com.ibm.ws.webcontainer.webapp                               
E SRVE0315E: An exception occurred: java.lang.Throwable: 
javax.servlet.ServletException: /pltdisable.xhtml - No saved view state 
could be found for the view identifier: /pltdisable.xhtml
at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:5006)
at com.ibm.ws.webcontainer.osgi.DynamicVirtualHost$2.handleRequest(DynamicVirtualHost.java:314)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:995)
at com.ibm.ws.webcontainer.osgi.DynamicVirtualHost$2.run(DynamicVirtualHost.java:279)
at com.ibm.ws.http.dispatcher.internal.channel.HttpDispatcherLink$TaskWrapper.run(HttpDispatcherLink.java:1009)
at com.ibm.cics.wlp.impl.CICSHttpRunnable.run(CICSHttpRunnable.java:244)
at com.ibm.cics.wlp.impl.CICSTaskWrapper.runWork(CICSTaskWrapper.java:762)
at com.ibm.cics.wlp.impl.CICSTaskWrapper.run(CICSTaskWrapper.java:415)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1160)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at com.ibm.cics.wlp.threading.CICSThread.run(CICSThread.java:245)
at com.ibm.cics.wlp.threading.CICSPooledThreadFactory.joinAsThreadInternal(CICSPooledThreadFactory.java:409)
at com.ibm.cics.wlp.threading.CICSPooledThreadFactory.joinAsThread(CICSPooledThreadFactory.java:335)
at com.ibm.cics.server.internal.ThreadJoiner.main(ThreadJoiner.java:106)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:90)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:508)
at com.ibm.cics.server.Wrapper.call_main(Wrapper.java:893)
at com.ibm.cics.server.Wrapper.callOSGiClass(Wrapper.java:2816)
at com.ibm.cics.server.Wrapper.invokeJvmServerOSGiClass(Wrapper.java:2683)
at com.ibm.cics.server.Wrapper.jvmServerOSGiEntry(Wrapper.java:2612)
at com.ibm.cics.osgi.impl.Controller.runService(Controller.java:1413)
at com.ibm.cics.osgi.impl.Controller.acceptRequest(Controller.java:322)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:90)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:508)
at com.ibm.cics.router.Router.route(Router.java:1317)
Caused by: javax.servlet.ServletException: /pltdisable.xhtml - No saved view 
state could be found for the view identifier: /pltdisable.xhtml
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:214)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1255)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:743)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:440)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1155)
at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:4962)
... 28 more

推荐答案

鉴于您的情况，当将请求路由到与其会话开始所在的服务器不同的服务器时，可能会发生No saved view state错误，并且新服务器无法处理其通过的视图状态.

Given your scenario, it's likely that the No saved view state error occurs when a request is routed to a different server than the one on which its session began, and that new server cannot process the view state it's passed.

之所以发生这种情况，是因为MyFaces默认情况下启用了视图状态加密-默认情况下，该加密的秘密密钥是在启动时随机生成的.因此，使用完全默认的配置，群集中的不同服务器将无法共享加密的视图状态，因为每个服务器都将使用不同的随机密钥进行初始化.为了在服务器之间共享加密的视图状态，需要将那些服务器配置为使用相同的密钥.可以通过以下Web配置参数进行设置:

This happens because MyFaces has view state encryption enabled by default - and by default, the secret keys for that encryption are generated randomly at startup. So given a completely default configuration, different servers in a cluster won't be able to share encrypted view states, because each server will have been initialized with a different random secret key. In order to share encrypted view states between servers, those servers need to have been configured to use the same secret keys. Those can be set via these web config parameters:

<!-- Defines the secret (Base64 encoded) used to initialize the secret key
     for encryption algorithm. The size of it depends on the algorithm used for encryption -->
<context-param>
    <param-name>org.apache.myfaces.SECRET</param-name>
    <param-value>your_secret_key</param-value>
</context-param>

<!-- Define the initialization code (Bas64 encoded) that are used to initialize the secret key used
     on the Message Authentication Code algorithm. The size of it depends on the algorithm used for mac calculation -->
<context-param>
    <param-name>org.apache.myfaces.MAC_SECRET</param-name>
    <param-value>your_mac_secret_key</param-value>
</context-param>

MyFaces Wiki 详细介绍了安全配置.除了安全密钥外，默认的安全参数设置也足以进行安全部署.

The MyFaces wiki details security configuration. The default security parameter settings - in addition to your secret keys - are sufficient for a secure deployment.

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