How to Canonicalize a Stax XML object.

Question

Hello, i want to Canonicalize a Stax object, the program it's doing it with DOM, but dom can't manage big XML documents (like 1GB), so STAX it's the solution.

The Code that i have it's:

File file=new File("big-1gb.xml");

org.apache.xml.security.Init.init(); 
DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance(); 
DocumentBuilder documentBuilder = dfactory.newDocumentBuilder();

Document doc = documentBuilder.parse(file);

Canonicalizer c14n = Canonicalizer.getInstance("http://www.w3.org/TR/2001/REC-xml-c14n-20010315");

outputBytes = c14n.canonicalizeSubtree(doc.getElementsByTagName("SomeTag").item(0));

The idea it's do the code below with Stax...

Thx :)

Answer 1

I solve this problem with XOM library, here is the equivalent code.

ByteArrayOutputStream bytestream = new ByteArrayOutputStream();
ObjectOutputStream outputstream = new ObjectOutputStream(bytestream);

nu.xom.Builder builder = new nu.xom.Builder(false, new nu.xom.samples.MinimalNodeFactory()); //The false parameter is for avoid a ValidationException that trows XOM

try {
nu.xom.canonical.Canonicalizer outputter = new nu.xom.canonical.Canonicalizer(outputstream);
nu.xom.Document input = builder.build(file);
outputter.write(input);
 }
catch (Exception ex) {
System.err.println(ex);
ex.printStackTrace();
}

outputstream.close();

MessageDigest sha1 = MessageDigest.getInstance("SHA1");
sha1.reset();
sha1.update(java.nio.ByteBuffer.wrap(bytestream.toByteArray()));
salidasha1=sha1.digest();
String tagDigestValue=new String(Base64.encodeBase64(salidasha1));

This code can manage files of 200Mb, and take 7 minutes to do the canonicalization, if you have doubt's, see the XOM documentation, it's pretty clear and have a lot of Examples.

Thx to all for your comments :)