Hi Walter,
*********** REPLY SEPARATOR ***********
On 13.03.2002 at 18:46 Walter Gamba wrote:
>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 had the same problem some months ago. And I re-implemented my servlets :(
I'm afraid there's no really elegant way to use POST (at least there wasn't one
when I tried it).
You might have a look at
http://marc.theaimsgroup.com/?t=101098813500002&r=1&w=2 ,
this thread contains some hints other people gave me about this topic.
Greetings,
Andreas
>----------------------------------------------
>
>We use Cocoon 2.0.1 and Tomcat 3.2.1, JDK 1.3.1.
>
>I've been trying to solve this proble since a week, but I've been quite
>unlucky, everyone refers to FileGenerator and HTMLGenrator, which doesn't
>work with a Servlet that needs POSTed parameters.
>
>I have a big servlet-based application that must be used from Cocoon. If
>possible, without rewrinting the whole application...
>This servlet generates XML responses, that are translated by cocoon to
>HTML.
>UNtil now we have used the request Action to invoke the servlet URL in the
>generator appending the query string, thus
>GET ting the parameters to the servlet.
>
>So for example the servlet is invoked in the generator by wrintig
>something
>like this
>
><map:generator src="it.test.BigServlet?{QUERY_STRING}"/>
>
>This worked fine for a test environment, but now we must go online.. and
>we
>must handle submit from forms that can have long input texts. So we need
>to
>POST data.
>
>I've written a generator that calls directly the (modified) Servlet code
>(that runs in the same Tomcat installation) by passing HttpRequest and
>HttpResponse to a ad-hoc service() method .. thus avoiding the overhead of
>another URL request.
>
>THe Generator emulates instantiation of servlet, intialization(only
>once..), and service calling.. the acutal sending of SAX events in the
>pipeline is done via a callback method in the generator.
>Since the servlet generates internally a Document (DOM), this Document
>must
>be "output" using a SAX parser, in the aforementioned callback method of
>the generator. (see later for details)
>
>If i put in the sitemap.xconf
>
>
><!-- define new generator -->
> <map:generator
>name="testgen" logger="sitemap.generator.testgen"
>label="content,data"
> src="TestGenerator"/>
> <!-- ...... -->
>
> <map:match pattern="test/test.html">
>
> <map:generate type="testgen" >
> <map:parameter name="servlet-class"
>value="TestServlet"/>
> </map:generate>
>
> < <map:serialize type="xml"/>
> </map:match>
>
>
>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.. )
>
>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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