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Posted to c-users@xalan.apache.org by "Dunko, Greg" <Gr...@FMR.COM> on 2003/01/23 21:34:27 UTC
General usage questions
Hiya folks. In the last couple days I've been trying to wrap my head around
the Xalan/Xerces APIs and I've run into some trouble that I can't seem to
get by.
As background, I'm new to these APIs as the XML work I did a couple years
ago was done using MSXML on Windows so I'm quite new to this library. I've
tried looking at as much documentation and samples as I can but alas I have
been unable to locate a clear direction for what I'm trying to do. The
differences between the two libraries DOM models and the fact that the Xalan
api uses the now deprecated Xerces DOM objects has me quite confused as to
what I'm "supposed" to be doing to accomplish my task :)
The basic issue is that I am trying to do some XSL transformations. My
input is an XML string in memory, the stylesheet is in a file on disk, and
I'd like my output to be in memory also (not in a file). I'd prefer DOM
output instead of a string. It's not entirely clear to me on how to do
this.
My initial attempt was to use a std::stringstream object to construct an
XSLTInputSource object but this didn't seem to work at all. Currently I
have some code using the deprecated Xerces API to produce a DOM_Document.
I'm then running that through the ParserLiasion and
XercesDOMWrapperParsedSource objects to get it into the transform. This
seems to work ok as long as the XSLTResultTarget points to a file on disk.
My problem is that as soon as I try to make the output of the transformation
use a XalanDocument it fails. I tried following what the documentation
describes:
XalanTransformer theXalanTransformer;
XercesDOMSupport theDOMSupport;
XercesParserLiaison theParserLiaison(theDOMSupport);
// Produce input and stylesheet InputSources
....
//
XalanDocument* docOut = theParserLiaison.createDocument();
XSLTResultTarget theDOMResultTarget(docOut);
int theResult = theXalanTransformer.transform(parsedSource, stylesheet ,
theDOMResultTarget);
This seems to fail in the transform returning a -4. From inspecting the
code this seems to be some sort of XercesException but there is no
indication as to what the issue is. Remember that this works fine if
theDOMResultTarget is constructed with a simple filename URI such as
"output.xml". Just getting the DOM output doesn't seem to work for me.
For a bit I thought the liaison could only be used once so I made a second
one for making the XalanDocument but that didn't work either.
Am I going about this whole thing the wrong way, making it more difficult
than it needs to be? I would think this would be a fairly common task to
perform and I'm a bit perplexed at the moment.
Thanks for your help!
--
Greg Dunko
Fidelity Investments
603.791.8216
mailto:greg.dunko@fmr.com
Re: General usage questions
Posted by David N Bertoni/Cambridge/IBM <da...@us.ibm.com>.
Hi Greg,
First things first -- you should not use anything in Xerces for the inputs.
You can use a memory stream as input to a transformation and a file for the
stylesheet. It's not clear to me from your posting if that's the case, but
can I assume it is? If not, take a look at the StreamTransform sample
program. It will illustrate how to use anything that derives from
std::istream for input.
For the output, you can produce serialized XML in memory by using
std::ostream. Take a look at the StreamTransform sample for that. You can
then parse that XML, or process it in any other way you want.
You can also produce the deprecated Xerces DOM on output, but not the new
one. In the next release of Xalan, you will be able to produce the new
Xerces DOM. This is probably what you want to do if you're going to
manipulate the tree after you've transformed it, although I don't know what
manipulations you could do in code that you can't do in your stylesheet.
Lastly, you can produce Xalan's source tree on output, which is a DOM-like
tree, but is not mutable. You might want to do this if you're going to do
a two-stage transformation where the output of the first stage is the input
to the second stage.
For more information on producing the Xerces DOM or Xalan's source tree,
look at the testXSLT program, which does either one, based on a command
line switch.
Now, the reason for the error -- this is not a XercesException, from what I
can see, instead, it's a XalanDOMException. Can you please confirm that?
If so, take a look at the error string returned from
XalanTransformer::getLastError(). My guess is the error code will be 3,
which is HIERARCHY_REQUEST_ERR. For more info, see the FAQ:
http://xml.apache.org/xalan-c/faq.html#faq-14
Hope that helps.
Dave
"Dunko, Greg"
<Greg.Dunko@FMR. To: "'xalan-c-users@xml.apache.org'" <xa...@xml.apache.org>
COM> cc: (bcc: David N Bertoni/Cambridge/IBM)
Subject: General usage questions
01/23/2003 12:34
PM
Hiya folks. In the last couple days I've been trying to wrap my head
around
the Xalan/Xerces APIs and I've run into some trouble that I can't seem to
get by.
As background, I'm new to these APIs as the XML work I did a couple years
ago was done using MSXML on Windows so I'm quite new to this library. I've
tried looking at as much documentation and samples as I can but alas I have
been unable to locate a clear direction for what I'm trying to do. The
differences between the two libraries DOM models and the fact that the
Xalan
api uses the now deprecated Xerces DOM objects has me quite confused as to
what I'm "supposed" to be doing to accomplish my task :)
The basic issue is that I am trying to do some XSL transformations. My
input is an XML string in memory, the stylesheet is in a file on disk, and
I'd like my output to be in memory also (not in a file). I'd prefer DOM
output instead of a string. It's not entirely clear to me on how to do
this.
My initial attempt was to use a std::stringstream object to construct an
XSLTInputSource object but this didn't seem to work at all. Currently I
have some code using the deprecated Xerces API to produce a DOM_Document.
I'm then running that through the ParserLiasion and
XercesDOMWrapperParsedSource objects to get it into the transform. This
seems to work ok as long as the XSLTResultTarget points to a file on disk.
My problem is that as soon as I try to make the output of the
transformation
use a XalanDocument it fails. I tried following what the documentation
describes:
XalanTransformer theXalanTransformer;
XercesDOMSupport theDOMSupport;
XercesParserLiaison theParserLiaison(theDOMSupport);
// Produce input and stylesheet InputSources
....
//
XalanDocument* docOut = theParserLiaison.createDocument();
XSLTResultTarget theDOMResultTarget(docOut);
int theResult = theXalanTransformer.transform(parsedSource, stylesheet ,
theDOMResultTarget);
This seems to fail in the transform returning a -4. From inspecting the
code this seems to be some sort of XercesException but there is no
indication as to what the issue is. Remember that this works fine if
theDOMResultTarget is constructed with a simple filename URI such as
"output.xml". Just getting the DOM output doesn't seem to work for me.
For a bit I thought the liaison could only be used once so I made a second
one for making the XalanDocument but that didn't work either.
Am I going about this whole thing the wrong way, making it more difficult
than it needs to be? I would think this would be a fairly common task to
perform and I'm a bit perplexed at the moment.
Thanks for your help!
--
Greg Dunko
Fidelity Investments
603.791.8216
mailto:greg.dunko@fmr.com