Hi to all..
This is a repost of a previously unansweered mail :) if somebody could
help I'll be eternally grateful :)
Summary:
I've written a Generator that calls a servlet object directly without
passing again via HTTP/tomcat (i.e. it istantiate the servlet object if not
already created, then calls a "service-like" method that returns an XML
(wrapped ina DOM's Document). Unfortunately i have:
1) problems with namespace.. hope to solve them or to be more precise next
time (XSL is not applied when I have a namespace prefixed to node names...
weird because if I write a staitc XML file that has exactly the same output
returned by the servlet, it works..)
2) serious problem with ContentHandler: Generator.ContentHandler is NULL
one invokation, not null the following, NULL... not null, null not null
alternatively... why?? why???
Thanx a lot
Walter
---start repost---
Thanx 4 all the help ..
unfortunately I can't install Tomcat4 so I'll stick with this soultion
>
>>Hello!
>>
>>SUMMARY: How to use a servlet as a generator in Cocoon, but allowing
>>forms data to be passed via POST method (And NOT GET!!)
>>----------------------------------------------
>>
>>
>>I can obtain correct XML output, provided I am happy with the raw XML
>>and i don't translate it .. (and a side question could be.. how can I
>>make the transformation from DOM to SAX efficiently, using some
>>xml.apache.org library.. without serializing the DOM on a Stream and
>>parsing it back?? THis brute force approach is the one I use now... but
>>this is another question.. i suppose.. )
>
>
>Cocoon provides helpers to deal with DOM2SAX and SAX2DOM :
>org.apache.cocoon.xml.dom.DOMStreamer in your case. Look at Javadocs if
>this matches your needs.
Il'' see it in a while when I've resolved every other issue.. .. see below..
>Concerning your NPE, I already had the same : my mistake was to have sent
>two contentHandler.startDocument().
>And I think you may do so here according to your code : the first is
>explicitly written, and the second one may be implicit within the
>parser.parse().
Thanx! That was it!!!!!!!!!!.. now i can have the output without errors.
(erll.. sometimes).. It is still not parseed correctly by the XSL but I'll
manage.. it seem to be a problem with namespace only.. But I have another
nasty problem:
every other invokation of the servlet I get an exception because the
super.contentHandler of my generator is NULL. If i relaod it is not null,
if I reload again it is null (i've checked it by logging..) ..
Any idea?? I've found a vague refernce to this, stating that
"The content handler is NULL when trying to process
the SAX Events through the AbstractDOMTransformer."
but I can't see why it works every other invokation. THe generator is
recreated each time, I gather?
Thanks
Walter
>>THe Problem arises when I add a Trasformer:
>>
>> <map:match pattern="prova/test.html">
>> <map:generate type="testgen" >
>> <map:parameter name="servlet-class"
>> value="TestServlet"/>
>> </map:generate>
>> <map:transform src="stylesheets/prova/TestServlet.xsl"/>
>> <map:serialize type="html"/>
>> </map:match>
>>
>>I've made the xsl such that it works fine with our testServlet and the
>>requestGenerator:
>>...
>> <map:generate type="request" />
>> <map:transform src="stylesheets/prova/TestServlet.xsl"/>
>>
>>With the request generator it works fine and I get neatly formatted HTML,
>>with our servlet, that apparently generates the same kind of XMLm it
>>breaks down..
>>
>>Or, to be correct, it does not match any tags. The XSL is read because in
>>the browser the basic HTML tags and title of the page (as specified inthe
>>top level XSL "/" template-mathcing rule) are displayed, but any further
>>XML tag is ignored, and moreover cocoon complains:
>>
>>FATAL_E (2002-03-13) 09:54.57:446 [core.xslt-processor]
>>(/cocoon/prova/test.html) Thread-20/TraxErrorHandler: Error in
>>TraxTransformer: javax.xml.transform.TransformerException:
>>java.lang.NullPointerException
>>javax.xml.transform.TransformerException: java.lang.NullPointerException
>> at
>>
>org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerImpl.java:1230)
>>
>> at
>> org.apache.xalan.transformer.TransformerImpl.run(TransformerImpl.java:3139)
>> at java.lang.Thread.run(Thread.java:484)
>>---------
>>java.lang.NullPointerException
>> at
>>
>org.apache.xalan.transformer.TransformerImpl.applyTemplateToNode(TransformerImpl.java:1887)
>
>>
>> at
>>
>org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerImpl.java:1175)
>>
>> at
>> org.apache.xalan.transformer.TransformerImpl.run(TransformerImpl.java:3139)
>> at java.lang.Thread.run(Thread.java:484)
>>
>>
>>THat's it. I enclose the bit of code of the Generator that translated a
>>DOM to SAX events.. perhaps there is something here that works with raw
>>XML but breaks down when SAX events are sent down the pipeline..
>>
>>Any help would be appreciated!
>>Thanx
>>
>>Walter Gamba
>>
>>-----------------------
>>public synchronized void outputXML(String NSURI, Document doc)
>>{
>> try{
>> super.contentHandler.startDocument();
>> //super.contentHandler.startPrefixMapping("",NSURI);
>> transformDOM2SAX(super.contentHandler,doc);
>> //super.contentHandler.endPrefixMapping("");
>> super.contentHandler.endDocument();
>> }catch(SAXException s){
>> log.error("Errore SAX!:"+s);
>> }
>>}
>>
>>private static /* synchronized */ void transformDOM2SAX(ContentHandler
>>cHandler, Document doc) {
>> //brute force way
>>try {
>> //1) open stream
>> CharArrayWriter writer = new CharArrayWriter();
>>
>> printDocument(writer, doc);
>>
>> //2) create SAX parserthat can read from stream
>> SAXParserFactory spf = SAXParserFactory.newInstance();
>> SAXParser parser = spf.newSAXParser();
>>
>> //3) build a reader and InputSource
>> Reader reader = new CharArrayReader(writer.toCharArray());
>> InputSource source = new InputSource(reader);
>>
>> log.debug("TestGenerator::transformDOM2SAX -> parse");
>> ServletDefaultHandler sdh=new ServletDefaultHandler(cHandler);
>> try{
>> parser.parse(source, sdh);
>> }
>> catch(Exception npe){
>> log.error("Errore in PARSE:"+npe,npe);
>> }
>> //writer.close();
>> log.debug("TestGenerator::transformDOM2SAX -> end parse");
>>
>>}
>>catch (IOException ioe) {
>> log.error("Errore in creazione reader/writer oppure in source:"
>> + ioe, ioe);
>>}
>>catch (ParserConfigurationException pfe) {
>> log.error("Errore parseconfig!:" + pfe, pfe);
>>}
>>catch (SAXException sax) {
>> log.error("Errore sax!:" + sax, sax);
>>}
>>
>>
>>Walter Gamba
>>[EMAIL PROTECTED]
>>E-Gramma srl
>>via Palazzo di Citta' 8 - 10122 TORINO
>>tel 011-5136583 fax 011-5136582
>>www.e-gramma.it
>>
>>
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>
>
>
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Walter Gamba
[EMAIL PROTECTED]
E-Gramma srl
via Palazzo di Citta' 8 - 10122 TORINO
tel 011-5136583 fax 011-5136582
www.e-gramma.it
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