[solved]Struts 2 and Vaadin

[Tudor Raneti]

The actual question is how can i provide a "do nothing" struts 2 action for the error message described below.

I want to embed a Vaadin application in a JSP used by Struts 2.
While the Vaadin part is sound, beeing a separate servlet, Struts 2 goes into an endless loop saying:
it can't find a There is no Action mapped for action name VaadinvizApplication/UIDL/
so, whatever communication Vaadin is doing, i don't want struts 2 meddling with it if i can. How do i configure struts 2 for that in this case?

[David Newton]

I'm not sure what you're asking--what do you need a Struts 2 action for if it's a servlet?

[Tudor Raneti]

While displaying the web page, it goes in an infinite loop, displaying this error:
There is no Action mapped for action name VaadinvizApplication/UIDL/
VaadinvizApplication beeing my Vaadin servlet mapped path. Vaadin communicates through UIDL a lot asynchronously.
Struts 2 catches every request / response like an action and wants to do something about it since it filters everything with /*
UIDL is a Vaadin class that gets called asynchronously often, but i don't want Struts 2 to be doing anything about it.
That's why i asked "how can i provide a 'do nothing' struts 2 action".
I want to know how to map VaadinvizApplication/UIDL/ so i can just return "success" or nothing to the same page because i don't want to do nothing with the Struts 2 action.

P.S. I suspect the communication starts from Vaadin through UIDL, and sometime, Struts 2 gets in the way filtering the response by not beeing mapped, and it doesn't get to Vaadin.
If Struts 2 would just forward or ignore the Vaadin comms, i believe there wouldn't be a problem.

I got a war hosted here (but you have to get JSTL, Struts 2, c and sql tlds, Vaadin jar):
http://vaadin.com/forum/-/message_boards/message/99801

[David Newton]

Did you try mapping the servlet first in the web.xml?

[Tudor Raneti]

This is my web.xml:

  <?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	id="WebApp_ID" version="2.5">
	<display-name>loto</display-name>
	<welcome-file-list>
		<welcome-file>main</welcome-file>
	</welcome-file-list>
	<filter>
		<filter-name>struts2</filter-name>
		<filter-class>
			org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>struts2</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	<servlet>
		<servlet-name>VaadinvizApplication</servlet-name>
		<servlet-class>com.vaadin.terminal.gwt.server.ApplicationServlet</servlet-class>
		<init-param>
			<param-name>application</param-name>
			<param-value>VaadinLotoTest.app.VaadinvizApplication</param-value>
		</init-param>
		<init-param>
			<param-name>widgetset</param-name>
			<param-value>VaadinLotoTest.app.widgetset.VaadinWidgetset</param-value>
		</init-param>
	</servlet>

	<servlet-mapping>
		<servlet-name>VaadinvizApplication</servlet-name>
		<url-pattern>/VaadinvizApplication/*</url-pattern>
	</servlet-mapping>
</web-app>  

[David Newton]

Oh, right; I forgot S2 uses a filter--oops ;)

Are you in development mode? I guess I thought if S2 didn't see an action suffix (whatever you have that defined as--if you have a blank this could be causing the problem) it'd just pass it on without giving an error.

[Tudor Raneti]

How would that action look?
I made this experiment sending the result to the test2.jsp (simplified example - link below),
and i noticed this: struts 2 loads the jsp that embeds the Vaadin app, which communicates with its server counterpart for syncronization or something. Struts 2 catches this as an action, and since i send the response back to the page, the embedded vaadin app gets loaded again, which instead sends the UIDL communication again, which creates the infinite loop. How would i get out of this endless loop by configuring struts 2 properly. I want Struts 2 to ignore anything that contains "UIDL" for instance.
war here:
http://vaadin.com/forum/-/message_boards/message/99801

my struts.xml:

  <!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>
	<package name="default" extends="struts-default">
		<action name="test">
			<result name="success">test2.jsp</result>
		</action>
		<action name="*">
			<result name="success">test2.jsp</result>
		</action>
		<action name="VaadinvizApplication/UIDL/">
			<result name="success">test2.jsp</result>
		</action>
	</package>
</struts>  

[David Newton]

I'm saying that you shouldn't have an action defined if you don't want Struts 2 to process a URL.

[Tudor Raneti]

With no action defined, i get:
There is no Action mapped for namespace / and action name . - [unknown location]
when trying to acces the JSP i get:
There is no Action mapped for action name VaadinStruts2Application/UIDL/. - [unknown location]

still in the infinite loop too.

Doesn't seem to matter what i map (except i don't get the errors now):

  <action name="VaadinStruts2Application/UIDL/">
			<result type="redirectAction"></result>
		</action>  

[Tudor Raneti]

Ok, seems i've done it, the struts 2 just needs to send the intercepted UIDL to 'there be dragons', since it isn't suppose to do anything to it. I wish i knew how to ignore 'UIDL' requests. I'll update the war in the other forum with a working war.

  <struts>
	<package name="default" extends="struts-default">
		<action name="VaadinStruts2Application/UIDL/">
			<result type="redirectAction">test.html</result>
			<result name="success">relief.jsp</result>
		</action>
	</package>
</struts>  

[David Newton]

I'm still not convinced I understand the problem, as we have several servlets working just fine in our S2 apps without it throwing any errors :/

[David Newton]

What version of S2 are you using? You never answered what your action extension is--if it's S2.1 the default includes extension-less actions, which could be the problem.

[Tudor Raneti]

2.1.8.1
Vaadin framework has a client - server communication set up over a wrapper on top of JSON. Struts 2 hooks into that, although i don't understand perfectly well how i ended up in the infinite loop. As i observed, every time Vaadin gets embedded into the page, it sends a communication to its server side to be rendered. My guess is because i was responding with the same page, the embedding happened again, the communication happened again, and so on and so forth, an infinite loop.

[David Newton]

Okay, did you understand what I said?

[Tudor Raneti]

No didn't quite get that, you mean the classes that don't need to subclass ActionSupport?
I knew this. Don't they need their name to end in Action?
I can't relate to my problem with that.

[David Newton]

No, I mean that in Struts 2.0, the action extension was ".action". URLs not ending in ".action" were ignored.

In Struts 2.1 the action extension is ".action,,". URLs without an extension are *NOT* ignored by Struts. If you change the action extension to ".action" your problem will go away and you won't need to map an "empty" action to the servlet URL.

[Tudor Raneti]

Ok, sorry but i still don't get it, how would i call my page?
When calling: http://localhost:8080/VaadinStruts2/test.action
i receive: There is no Action mapped for namespace / and action name test. - [unknown location]
I even wrote a test class, still doesn't work.

[David Newton]

I don't understand. I thought your issue was that when calling the servlet you were getting S2 errors. The action extension setting is why.

[Tudor Raneti]

The actual flow is like this:
i call http://localhost:8080/VaadinStruts2/test.jsp
in test.jsp i have:

  <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en" />
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

<script type="text/javascript">
	var vaadin = {
		vaadinConfigurations : {
			'fb' : {
				appUri : '/VaadinStruts2/VaadinStruts2Application',
				pathInfo : '/',
				themeUri : '/VaadinStruts2/VAADIN/themes/reindeer',
				versionInfo : {
					vaadinVersion : "6.2.0-INTERNAL-NONVERSIONED-DEBUG-BUILD",
					applicationVersion : "NONVERSIONED"
				}
			}
		}
	};
</script>
<script type="text/javascript"
	src='/VaadinStruts2/VAADIN/widgetsets/VaadinStruts2.app.widgetset.VaadinStruts2Widgetset/VaadinStruts2.app.widgetset.VaadinStruts2Widgetset.nocache.js'></script>
<link rel="stylesheet" type="text/css"
	href="/VaadinStruts2/VAADIN/themes/reindeer/styles.css" />
</head>
<body>
	<div id="fb" style="height: 400px; border: 2px solid red; margin: 0"></div>
</body>
</html>  

which embeds Vaadin. At this point i suspect a UIDL communication starts from AJAX, triggering the struts2 filter, which messes things up.
i even tried <url-pattern>/VaadinStruts2Application/*.action</url-pattern>, because the UIDL is the culprit i think, although it appends a '/' as you can see above and i can't guess what the mapping should look like.

[David Newton]

I'm saying that if you fix the action extension configuration you shouldn't have a problem.

[Tudor Raneti]

I understood that, thank you. However, i don't know how to apply that in my case other than downgrading to an older Struts 2. I tried appending .action everywhere it seemed logical.

EDIT: although this seems to work too, perhaps because it's sending the UIDL object nowhere again:

  <action name="VaadinStruts2Application/UIDL/">
			
			<result name="success">test.action</result>
		</action>  

[David Newton]

...

http://struts.apache.org/2.x/docs/strutsproperties.html

### Used by the DefaultActionMapper
### You may provide a comma separated list, e.g. struts.action.extension=action,jnlp,do
### The blank extension allows you to match directory listings as well as pure action names
### without interfering with static resources.
struts.action.extension=action,,

[Tudor Raneti]

Found struts2-core-2.1.8.1.jar\org\apache\struts2\default.properties
struts.action.extension=action,,
...so it should be ignored by default because the action .../UIDL/ ends in / ?
Lost again here, what should i write in:
<constant name="struts.action.extension" value="action,," /> in my struts.xml ?
Tried a couple of things, didn't work.

[David Newton]

Tudor Andrei Raneti wrote:
Lost again here, what should i write in:
<constant name="struts.action.extension" value="action,," /> in my struts.xml ?

No! That's what it is now! Remove the empty string suffix.

[Tudor Raneti]

Thank you very much, it works, still unsure what happends technically though
Now all the requests are seen as .action(s)?

  <struts>
<constant name="struts.action.extension" value="action" />
	<package name="default" extends="struts-default">
		
	</package>
</struts>  

[David Newton]

With the empty suffix Struts 2 will attempt to process all requests as actions.

[Tudor Raneti]

Bangarang Thank you very much. Now only *.action(s) match actions.

[David Newton]

Glad to hear we got it sorted out :)