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From "Max Pfingsthorn" <m.pfingsth...@hippo.nl>
Subject RE: error handling in aggregations
Date Tue, 21 Mar 2006 15:32:37 GMT
Hi!

Yes, this works well. I've tested it and with 'when="external"' on 'map:handle-errors', it
does stop the serializer from dumping the data before the error page. Also, 'when="internal"'
works wonderfully inside the aggregate!

I would be all for this change before 2.1.9 comes out. If noone objects, I'll commit it within
the hour.

max

> -----Original Message-----
> From: Bruno Dumon [mailto:bruno@outerthought.org]
> Sent: Sunday, March 19, 2006 14:33
> To: dev@cocoon.apache.org
> Subject: Re: error handling in aggregations
> 
> 
> On Sun, 2006-03-19 at 12:10 +0000, Jeremy Quinn wrote:
> > Hi All
> > 
> > Investigating this further, I came up with this simplest possible  
> > sitemap to reproduce the problem :
> > 
> > <?xml version="1.0"?>
> > <map:sitemap xmlns:map="http://apache.org/cocoon/sitemap/1.0">
> > 
> >    <map:components>
> >      <map:generators default="file">
> >        <map:generator name="file" label="content"  
> > logger="sitemap.generator.file" pool-grow="4" pool-max="32" pool- 
> > min="4" src="org.apache.cocoon.generation.FileGenerator"/>
> >     </map:generators>
> >      <map:serializers default="xml">
> >        <map:serializer name="xml" logger="sitemap.serializer.xml"  
> > mime-type="text/xml" pool-grow="4" pool-max="32" pool-min="4"  
> > src="org.apache.cocoon.serialization.XMLSerializer"/>
> >      </map:serializers>
> >      <map:matchers default="wildcard">
> >        <map:matcher logger="sitemap.matcher.wildcard" 
> name="wildcard"  
> > src="org.apache.cocoon.matching.WildcardURIMatcher"/>
> >      </map:matchers>
> >      <map:pipes default="noncaching">
> >        <map:pipe logger="sitemap.pipes.noncaching" 
> name="noncaching"  
> > 
> src="org.apache.cocoon.components.pipeline.impl.NonCachingProc
> essingPipe 
> > line">
> >          <parameter name="outputBufferSize" value="32768"/>
> >        </map:pipe>
> >      </map:pipes>
> >    </map:components>
> > 
> >    <map:pipelines>
> > 
> >      <map:pipeline internal-only="false" type="noncaching">
> > 
> >        <map:match pattern="test">
> >          <map:aggregate element="site">
> >            <map:part element="content1" src="nothing.xml"/>
> >            <map:part element="content2" src="nothingelse.xml"/>
> >          </map:aggregate>
> >          <map:serialize type="xml" />
> >        </map:match>
> > 
> >      </map:pipeline>
> > 
> >    </map:pipelines>
> > 
> > </map:sitemap>
> > 
> > I set this up as the top-level sitemap, loaded by cocoon.xconf.
> > 
> > I access the url and I get this :
> > 
> > $ curl http://localhost:8888/test
> > <?xml version="1.0" encoding="ISO-8859-1"?><site><content1/></

> > site><html><head><title>Resource Not Found</title><style><!--body
 
> > { background-color: white; color: black; font-family: verdana,  
> > helvetica, sanf serif;}h1 {color: #336699; margin: 0px 0px 
> 20px 0px;  
> > border-width: 0px 0px 1px 0px; border-style: solid; border-color:  
> > #336699;}p.footer { color: #336699; border-width: 1px 0px 0px 0px;  
> > border-style: solid; border-color: #336699; }span {color: #336699;} 
> > pre {padding-left: 20px;}a:link {font-weight: bold; color: 
> #336699;} 
> > a:visited {color: #336699; }a:hover {color: #800000; background- 
> > color: #ffff80;}a:active {color: #006666;}--></style></ 
> > head><body><h1>Resource Not Found</h1><p><span>Message:</span>
 
> > Resource Not Found</p><p><span>Description:</span> The requested
 
> > resource &quot;/test&quot; could not be found</p><p><span>Sender:</

> > span> org.apache.cocoon.servlet.CocoonServlet</p><p><span>Source:</

> > span> Cocoon Servlet</p><p class='footer'><a href='http:// 
> > cocoon.apache.org/'>Apache Cocoon 2.1.9-dev</p></body></html>
> > 
> > Two outputs ....
> > 
> > First the content of the failed aggregation : 
> <site><content1/></site>
> > Then the generic error message.
> > 
> > 
> > If I now comment out the line "<parameter name="outputBufferSize"  
> > value="32768"/>" from the <map:pipe>. then I only get the 
> error message.
> > 
> > I have tested this in 2.1.7 --> 2.1.9-dev.
> > 
> > I suspect this did not occur in 2.1.6.
> > 
> > 
> > Is this a bug, or is it what I should expect to happen if 
> an output  
> > buffer is configured?
> 
> Hi Jeremy,
> 
> Given the streaming nature of the SAX pipeline, buffering the complete
> output at the end of the pipeline is indeed the only way to reliably
> recover from exceptions that might happen during its 
> execution. This is
> not necessarily bad, as whatever other way you would solve this, you
> would need to temporarily store the data in one way or another to be
> able to recover from errors.
> 
> There's a little bit more to it though. In case of an error the output
> your pipeline is quite small:
> 
> <?xml version="1.0" encoding="ISO-8859-1"?><site><content1/></site>
> 
> which is much less then your buffer size of 32768, so normally Cocoon
> should still be able to reset the output before generating the error
> page.
> 
> Someone asked the exact same question a week or two ago on the users
> list, at which time I had a quick look into this. The cause 
> is that the
> ContentAggregator class, which does the aggregation, will 
> still generate
> the endDocument event in case an exception occurs. IMO, it 
> should not do
> this (unless it would also catch the exception). Here is the relevant
> fragment:
> 
> 
>                 try {
>                     SourceUtil.parse(this.manager, part.source, this);
>                 } finally {
>                     if (part.element != null) {
>                         endElem(part.element);
>                     }
>                 }
>             }
>         } finally {
>             endElem(this.rootElement);
>             this.contentHandler.endDocument();
>         }
> 
> 
> I'd be in favor of removing these two finally blocks.
> 
> -- 
> Bruno Dumon                             http://outerthought.org/
> Outerthought - Open Source, Java & XML Competence Support Center
> bruno@outerthought.org                          bruno@apache.org
> 
> 

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