[jira] Commented: (TILES-286) TilesAccess won't set context attributes in Jetty 5.1.10

["Dmitry (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/struts/browse/TILES-286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=44470#action_44470 ] 

Dmitry commented on TILES-286:
------------------------------

Unfortunately I'm not able to upgrade Jetty on that particular server for which I'm developing an application. It's already running a number of critical applications and upgrading Jetty there means testing them all over again. My current task is to put a new application there so that it would work. Not using Tiles is probably the simplest way in my case. 

However when I found the bug I thought that an old Jetty might not be the only web server in which Tiles do not work. In any web server that implements ServletContext in the way Jetty 5 does (not public inner class) this bug will appear. The bug is connected to quite low-level things: java language access control and reflection.

I wonder why reflection is used in TilesAccess? Isn't it enough to cast the context variable to javax.servlet.ServletContext? I see the only reason to use reflection there: to implement "duck typing", i.e., accept contexts other than subclasses of javax.servlet.ServletContext. This is (probably) good but it doesn't work in all cases. The current implementation can be improved to support those weird cases as well.

> TilesAccess won't set context attributes in Jetty 5.1.10
> --------------------------------------------------------
>
>                 Key: TILES-286
>                 URL: https://issues.apache.org/struts/browse/TILES-286
>             Project: Tiles
>          Issue Type: Bug
>          Components: tiles-api
>    Affects Versions: 2.0.6
>         Environment: Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_12-b04), Jetty 5.1.11, SUSE Linux Enterprise 10, 64 bit
>            Reporter: Dmitry
>
> The code for setting a context attribute in the TilesAccess class is as follows: 
>     private static void setAttribute(Object context, String name, Object value) 
>         throws TilesException { 
>         try { 
>             Class<?> contextClass = context.getClass(); 
>             Method attrMethod = contextClass.getMethod("setAttribute", String.class, Object.class); 
>             attrMethod.invoke(context, name, value); 
>         } catch (Exception e) { 
>             throw new TilesException("Unable to set attribute for specified context: '" + context + "'"); 
>         } 
>     } 
> The line 
>             attrMethod.invoke(context, name, value); 
> throws an IllegalAccessException if Tiles are used inside a Jetty 5.1.11. This happens because Jetty's implementation of the javax.servlet.ServletContext interface is an inner class without the public modifier. 
> I.e., Jetty's org.mortbay.jetty.servlet.ServletHandler$Context is not public although it's setAttribute() is. 
> The same applies to getAttribute() and removeAttribute() methods.
> One of the possible solutions is to reflect the method not only from the class itself, but from all its superclasses and interfaces as well.

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