Endless exception loop caused by invalid EL expression in a decision node of a page flow

[ask777]

Seam version: 2.1.1.GA

Set up a seam page flow with a decision node. Place an invalid expression in the decision node. Execute the page flow. An endless loop of exceptions
occur as shown below in the log snippets. The server needs to be stopped.

2009-04-07 08:51:26,745 ERROR [org.jboss.seam.bpm.SeamExpressionEvaluator] (http-localhost%2F127.0.0.1-8080-2) Exceptions occurred when parsing ${type1Flow.flowReturnValue(}
2009-04-07 08:51:26,745 ERROR [org.jboss.seam.bpm.SeamExpressionEvaluator] (http-localhost%2F127.0.0.1-8080-2) Possible cause
javax.el.ELException: Error Parsing: ${type1Flow.flowReturnValue(}
     at org.jboss.el.lang.ExpressionBuilder.createNodeInternal(ExpressionBuilder.java:130)
     at org.jboss.el.lang.ExpressionBuilder.build(ExpressionBuilder.java:151)
     at org.jboss.el.lang.ExpressionBuilder.createMethodExpression(ExpressionBuilder.java:213)
     at org.jboss.el.ExpressionFactoryImpl.createMethodExpression(ExpressionFactoryImpl.java:57)
     at org.jboss.seam.bpm.SeamExpressionEvaluator$1.initMethodExpression(SeamExpressionEvaluator.java:69)
     at org.jboss.seam.bpm.SeamExpressionEvaluator$1.evaluate(SeamExpressionEvaluator.java:87)
     at org.jboss.seam.bpm.SeamExpressionEvaluator.evaluate(SeamExpressionEvaluator.java:45)
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:39)
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:30)
     at org.jbpm.graph.node.Decision.execute(Decision.java:95)
     at org.jbpm.graph.def.Node.enter(Node.java:319)

.......

2009-04-07 08:51:26,745 ERROR [org.jboss.seam.bpm.SeamExpressionEvaluator] (http-localhost%2F127.0.0.1-8080-2) Possible cause
javax.el.ELException: Error Parsing: ${type1Flow.flowReturnValue(}
     at org.jboss.el.lang.ExpressionBuilder.createNodeInternal(ExpressionBuilder.java:130)
     at org.jboss.el.lang.ExpressionBuilder.build(ExpressionBuilder.java:151)
     at org.jboss.el.lang.ExpressionBuilder.createValueExpression(ExpressionBuilder.java:206)
     at org.jboss.el.ExpressionFactoryImpl.createValueExpression(ExpressionFactoryImpl.java:68)
     at org.jboss.seam.bpm.SeamExpressionEvaluator$1.initValueExpression(SeamExpressionEvaluator.java:77)
     at org.jboss.seam.bpm.SeamExpressionEvaluator$1.evaluate(SeamExpressionEvaluator.java:107)
     at org.jboss.seam.bpm.SeamExpressionEvaluator.evaluate(SeamExpressionEvaluator.java:45)
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:39)
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:30)
     at org.jbpm.graph.node.Decision.execute(Decision.java:95)


2009-04-07 08:51:26,745 WARN  [javax.enterprise.resource.webcontainer.jsf.lifecycle] (http-localhost%2F127.0.0.1-8080-2) couldn't evaluate expression '#{type1Flow.flowReturnValue(}'
org.jbpm.JbpmException: couldn't evaluate expression '#{type1Flow.flowReturnValue(}'
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:43)
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:30)
     at org.jbpm.graph.node.Decision.execute(Decision.java:95)
     at org.jbpm.graph.def.Node.enter(Node.java:319)
     at org.jbpm.graph.def.Transition.take(Transition.java:151)
     at org.jbpm.graph.def.Node.leave(Node.java:394)
     at org.jbpm.graph.node.ProcessState.leave(ProcessState.java:242)
     at org.jbpm.graph.exe.Token.signal(Token.java:195)
     at org.jbpm.graph.exe.Token.signal(Token.java:171)
     at org.jbpm.graph.exe.ProcessInstance.end(ProcessInstance.java:323)
     at org.jbpm.graph.exe.Token.notifyParentOfTokenEnd(Token.java:332)
     at org.jbpm.graph.exe.Token.end(Token.java:304)
     at org.jbpm.graph.exe.Token.end(Token.java:254)
     at org.jbpm.graph.node.EndState.execute(EndState.java:59)
     at org.jbpm.graph.def.Node.enter(Node.java:319)
     at org.jbpm.graph.def.Transition.take(Transition.java:151)
     at org.jbpm.graph.def.Node.leave(Node.java:394)
     at org.jbpm.graph.exe.Token.signal(Token.java:195)
     at org.jbpm.graph.exe.Token.signal(Token.java:158)
     at org.jbpm.graph.exe.ProcessInstance.signal(ProcessInstance.java:283)
     at org.jboss.seam.pageflow.Pageflow.signal(Pageflow.java:485)
     at org.jboss.seam.pageflow.Pageflow.navigate(Pageflow.java:341)
     at org.jboss.seam.jsf.SeamNavigationHandler.handleNavigation(SeamNavigationHandler.java:40)
     
Caused by: org.jbpm.jpdl.el.ELException: Error parsing ${type1Flow.flowReturnValue(}; not a valid EL expression
     at org.jboss.seam.bpm.SeamExpressionEvaluator$1.evaluate(SeamExpressionEvaluator.java:140)
     at org.jboss.seam.bpm.SeamExpressionEvaluator.evaluate(SeamExpressionEvaluator.java:45)
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:39)
     ... 74 more
2009-04-07 08:51:26,745 ERROR [javax.enterprise.resource.webcontainer.jsf.lifecycle] (http-localhost%2F127.0.0.1-8080-2) JSF1054: (Phase ID: INVOKE_APPLICATION 5, View ID: /type_1.xhtml) Exception thrown during phase execution: javax.faces.event.PhaseEvent[source=com.sun.faces.lifecycle.LifecycleImpl@1f759c0]
2009-04-07 08:51:26,745 WARN  [org.jboss.seam.web.ExceptionFilter] (http-localhost%2F127.0.0.1-8080-2) handling uncaught exception
javax.servlet.ServletException: couldn't evaluate expression '#{type1Flow.flowReturnValue(}'
     at javax.faces.webapp.FacesServlet.service(FacesServlet.java:277)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:73)
     at org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
     
Caused by: org.jbpm.jpdl.el.ELException: Error parsing ${type1Flow.flowReturnValue(}; not a valid EL expression
     at org.jboss.seam.bpm.SeamExpressionEvaluator$1.evaluate(SeamExpressionEvaluator.java:140)
     at org.jboss.seam.bpm.SeamExpressionEvaluator.evaluate(SeamExpressionEvaluator.java:45)
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:39)
     ... 74 more
2009-04-07 08:51:26,745 WARN  [org.jboss.seam.web.ExceptionFilter] (http-localhost%2F127.0.0.1-8080-2) exception root cause
org.jbpm.JbpmException: couldn't evaluate expression '#{type1Flow.flowReturnValue(}'
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:43)
     at org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator.evaluate(JbpmExpressionEvaluator.java:30)
     at org.jbpm.graph.node.Decision.execute(Decision.java:95)
     at org.jbpm.graph.def.Node.enter(Node.java:319)
     
2009-04-07 08:51:26,761 WARN  [org.jboss.seam.web.ExceptionFilter] (http-localhost%2F127.0.0.1-8080-2) running exception handlers
2009-04-07 08:51:26,808 WARN  [org.jboss.seam.jsf.SeamPhaseListener] (http-localhost%2F127.0.0.1-8080-2) uncaught exception, passing to exception handler
java.lang.IllegalStateException: pageflow is not currently at a <page> or <start-page> node (note that pageflows that begin during the RENDER_RESPONSE phase should use <start-page> instead of <start-state>)
     at org.jboss.seam.pageflow.Pageflow.getPage(Pageflow.java:232)
     at org.jboss.seam.faces.FacesManager.prepareBackswitch(FacesManager.java:263)
     at org.jboss.seam.jsf.SeamPhaseListener.afterRenderResponse(SeamPhaseListener.java:505)
     at org.jboss.seam.jsf.SeamPhaseListener.afterServletPhase(SeamPhaseListener.java:247)
     at org.jboss.seam.jsf.SeamPhaseListener.afterPhase(SeamPhaseListener.java:194)
     at com.sun.faces.lifecycle.Phase.handleAfterPhase(Phase.java:175)
     at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:114)
     at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
     
2009-04-07 08:51:26,870 WARN  [org.jboss.seam.jsf.SeamPhaseListener] (http-localhost%2F127.0.0.1-8080-2) uncaught exception, passing to exception handler
java.lang.IllegalStateException: pageflow is not currently at a <page> or <start-page> node (note that pageflows that begin during the RENDER_RESPONSE phase should use <start-page> instead of <start-state>)
     at org.jboss.seam.pageflow.Pageflow.getPage(Pageflow.java:232)
     at org.jboss.seam.faces.FacesManager.prepareBackswitch(FacesManager.java:263)
     at org.jboss.seam.jsf.SeamPhaseListener.afterRenderResponse(SeamPhaseListener.java:505)
     at org.jboss.seam.jsf.SeamPhaseListener.afterServletPhase(SeamPhaseListener.java:247)
     at org.jboss.seam.jsf.SeamPhaseListener.afterPhase(SeamPhaseListener.java:194)
     at com.sun.faces.lifecycle.Phase.handleAfterPhase(Phase.java:175)
     at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:114)
     at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
     at javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
     at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
     
2009-04-07 08:51:26,886 WARN  [org.jboss.seam.jsf.SeamPhaseListener] (http-localhost%2F127.0.0.1-8080-2) uncaught exception, passing to exception handler
java.lang.IllegalStateException: pageflow is not currently at a <page> or <start-page> node (note that pageflows that begin during the RENDER_RESPONSE phase should use <start-page> instead of <start-state>)
     at org.jboss.seam.pageflow.Pageflow.getPage(Pageflow.java:232)
     at org.jboss.seam.faces.FacesManager.prepareBackswitch(FacesManager.java:263)
     at org.jboss.seam.jsf.SeamPhaseListener.afterRenderResponse(SeamPhaseListener.java:505)
     at org.jboss.seam.jsf.SeamPhaseListener.afterServletPhase(SeamPhaseListener.java:247)
     
     

[oguzyalcin.oguzhanyalcin.gazi.edu.tr]

i think the problem is with the EL. I saw the EL has a missing close bracket.

${type1Flow.flowReturnValue(}

you can basically add a closing bracket for the method flowReturnValue the code will be

${type1Flow.flowReturnValue()}

or

${type1Flow.flowReturnValue}

[ssunkara.rinit_r.yahoo.com]

I am in a similar situation..I am sure my el is good and I have the same exact behavior..I can add an entry in pages.xml to bypass this endless loop, but I would really like to see what the root exception is and a better way of handling this.

This is driving me NUTS!!!!

[ssunkara.rinit_r.yahoo.com]

Also, I believe it has to do with the combination of jpdl and jsf el. I say this because, if an exception occurs in a jpdl expression, jpdl will throw an exception and will attempt to continue with the pageflow. But it looks like jsf is trying to invoke the same expression(that just failed) again and it goes in an infinite loop.

I also think the view may be doing a post to itself and it could be another possibility.

In any case, if someone has more clarity on this issue, please drop your 2 cents.

[ssunkara.rinit_r.yahoo.com]

https://jira.jboss.org/jira/browse/JBSEAM-2152

This will answer atleast some of your prayers