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Re: rdfa parsing issue -- was: fixed https://foafssl.org/test/WebId

From: Henry Story <henry.story@bblfish.net>
Date: Sat, 7 Jan 2012 14:46:10 +0100
Cc: "public-xg-webid@w3.org XG" <public-xg-webid@w3.org>, Damian Steer <pldms@mac.com>
Message-Id: <163F5360-2FC9-420F-A3BA-B2A63BD08BF5@bblfish.net>
To: Jürgen Jakobitsch <j.jakobitsch@semantic-web.at>

On 6 Jan 2012, at 22:03, Jürgen Jakobitsch wrote:

> henry,
> 
> i had exactly the same problem with rdfa parser from openrdf and DTD.

Do you know of a good way to reproduce this? I have tried with your profile

   http://2sea.org/sea.jsp

but when I try this locally with pretty much the same code base I never get 
the same error

> ERROR [pool-3-thread-5] (RDFDefaultErrorHandler.java:40) - http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd(line 106 column 22): {E213} Unexpected end of file from server

So it's a bit difficult for me to work out if I am fixing the problem.

> 
> 
> what you wanna do is :
> 
> 1. create a catalog (catalog.xml and download all DTDs)
> 2. add file "CatalogManager.properties" to the classpath (in a maven project on netbeans you would simply put it in "other resources", so it gets jar'd)
> 3. modify the code so the xml reader uses that catalog.
> 
> my parser looks about so :
> 
>   CatalogResolver catRes
>   Transformer transformer
> 
> constructor
> 
>   TransformerFactory transFact = TransformerFactory.newInstance();
>   CatalogManager catMan = new CatalogManager("CatalogManager.properties");
>   catRes = new CatalogResolver(catMan);
>   ClassLoader cl = RDFaParser.class.getClassLoader();
>   Templates cachedXSLT = transFact.newTemplates(new StreamSource(cl.getResourceAsStream(XSLT)));
>               transformer = cachedXSLT.newTransformer();
>               transformer.setURIResolver(catRes);
> 
> parserMethod (StreamSource source)
> 
> XMLReader reader = XMLReaderFactory.createXMLReader();
>          reader.setEntityResolver(catRes);
>          reader.setFeature("http://xml.org/sax/features/validation", Boolean.FALSE);
>          Source sXML=new SAXSource(reader, new InputSource(source.getInputStream()));
> 	  transformer.transform(sXML, new StreamResult(out));                     
> 
> 
> it took me some time to get this catalog thing up and running, here are some links,
> 
> 1. http://www.w3.org/blog/systeam/2008/02/08/w3c_s_excessive_dtd_traffic/  (see here for the overall trouble)
> 2. http://xml.apache.org/commons/components/resolver/resolver-article.html
> 3. http://nwalsh.com/docs/articles/xml2003/
> 4. http://xerces.apache.org/xerces2-j/faq-xcatalogs.html
> 5. http://www.sagehill.net/docbookxsl/WriteCatalog.html
> 6. http://xml.apache.org/mirrors.cgi (download apache's resolver)
> 
> to save you some time :
> 
> 1. find the catalog.xml and the catalog in use by WebIDRealm attached (copy the contents of catalog.zip to /usr/share/catalogs/ and make sure the files are readable)
>   if you copy the contents elsewhere you need to change the path in CatalogManager.properties as well.
> 2. find the CatalogManager.properties in use by WebIDRealm attached
> 
> the basic workflow would :
> 
> 1. CatalogManager reads CatalogManager.properties and finds path of catalog.xml
> 2. when resolving CatalogResolver looks in catalog.xml to see, if the docType (or module) is mapped there and tries to find the file in
>   path specified in the catalog.xml.
> 
> 
> 
> if you have any questions regarding the catalog feel free to ask.
> 
> wkr j
> 
> ----- Original Message -----
> From: "Henry Story" <henry.story@bblfish.net>
> To: "Damian Steer" <pldms@mac.com>
> Cc: "Jürgen Jakobitsch" <j.jakobitsch@semantic-web.at>, "public-xg-webid@w3.org XG" <public-xg-webid@w3.org>
> Sent: Friday, January 6, 2012 9:10:58 PM
> Subject: Re: rdfa parsing issue -- was: fixed https://foafssl.org/test/WebId
> 
> Thanks Damian,
> 
>  that was very helpful.
> 
> I have now fixed a couple of issues on my side now, and I see that Jürgen has updated his xhtml even to be closer to xhtml. So the foafssl.org tester should work with that resource in any case.
> 
> Btw, I get the following in the logs
> 
> INF: [console logger] dispatch: 2sea.org GET /sea.jsp HTTP/1.1
> ERROR [pool-3-thread-5] (RDFDefaultErrorHandler.java:40) - http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd(line 106 column 22): {E213} Unexpected end of file from server
> 
> It looks like the RDFa parser is following the DTDs. Is there a way to stop that? I guess the W3C does not serve those files.
> 
> Henry
> 
> 
> On 6 Jan 2012, at 15:57, Damian Steer wrote:
> 
>> Hi Henry and Jürgen,
>> 
>> On 06/01/12 12:49, Henry Story wrote:
>> 
>>> Shellac's parser parses the xhtml correctly as xhtml in fact, but
>>> when the html parser is used it comes to a different conclusion.
>> 
>> Yes, this is becoming a classic issue, and has nothing to do with RDFa
>> (although RDFa obscures the issue horribly).
>> 
>>> RDFA 1 is defined in xhtml only I understand, so it is true that we
>>> are going beyond what the spec by trying to parse html too. Perhaps
>>> this will be a lot simplified with rdfa1.1 which can be made to work
>>> with html5.
>> 
>> Yes, RDFa 1.0 is only really defined for xhtml, although useful work was
>> done on html 5 at the time (there are some html 5 tests). RDFa 1.1 does
>> address html 5, but note that it doesn't change anything here.
>> 
>> The problem is this:
>> 
>>   <div rel="foaf:depiction" href="http://2sea.org/2sealogo.png"/>
>>   <div rel="cert:key">
>> 	...
>>   </div>
>> 
>> An xml parser sees a closed div, followed by another div. An html parser
>> sees a broken div so repairs it as follows:
>> 
>>   <div rel="foaf:depiction" href="http://2sea.org/2sealogo.png">
>>     <div rel="cert:key">
>>       ...
>>     </div>
>>   </div> <!-- close that div -->
>> 
>> i.e. one div contains another now, and thus you find
>> 
>> <http://2sea.org/2sealogo.png> cert:key ....
>> 
>> I ought to add a utility to switch the parser based on content type,
>> however in practice there's so much broken xhtml out there that tag soup
>> parsing is much safer (although it does lead to issues like this).
>> 
>> My advice would be to expect tag soup parsing in the wild and change the
>> html:
>> 
>>   <div rel="foaf:depiction" href="http://2sea.org/2sealogo.png"></div>
>> 
>> Hope this makes sense,
>> 
>> Damian
> 
> Social Web Architect
> http://bblfish.net/
> 
> 
> 
> --
> | Jürgen Jakobitsch,
> | Software Developer
> | Semantic Web Company GmbH
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> 
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> <RDFACatalog.zip><CatalogManager.properties>

Social Web Architect
http://bblfish.net/
Received on Saturday, 7 January 2012 13:46:48 GMT

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