Saxon

At present you can only do this by digging down to the underlying Java classes. The XsltTransformer.Implementation property takes you to the net.sf.saxon.Controller object, and this has methods getErrorListener() and setErrorListener(). You can write and register an ErrorListener that implements the interface javax.xml.transform.ErrorListener, or you can get the StandardErrorListener which is currently registered, and call its setLogger() method to change the destination of messages; you could use an instance of net.sf.saxon.lib.StandardLogger initialized to write to a specified file.

I'm afraid this all involves rather low-level grubbing around the innards, but it can be done.

Ahhh, okay. I supposed a solution like this, but it seems interesting. :) I think, I will try and if I am successful, I will post my solution. Thanks a lot.

I just implement the Interface. I think, it is very easy.

To use the classes and interfaces, you have to reference the libraries IKVM.OpenJDK.ClassLibrary.dll and of course the saxon9.dll. First I create a class "JavaErrorClass" and implements the "ErrorListener", using javax.xml.transform.

 public class JavaErrorListener : ErrorListener
    {
        private Logger _logger; //this is my Logger to save all messages in a SQL-Database
        private string _source; //this is the current file to transform

        public JavaErrorListener(Logger logger, string source)
        {
            _logger = logger;
            _source = source;
        }

        public void warning(TransformerException te)
        {
            if (te.getException() != null)
                _logger.LogException(te.getException(), TraceEventType.Warning);
            else
                _logger.LogMessage(string.Format("Warning for {0}: {1}", _source, te.Message), TraceEventType.Warning);
        }

        public void fatalError(TransformerException te)
        {
            if (te.getException() != null)
                _logger.LogException(te.getException(), TraceEventType.Error);
            else
                _logger.LogMessage(string.Format("Error for {0}: {1}", _source, te.Message), TraceEventType.Error);
        }

        public void error(TransformerException te)
        {
            if (te.getException() != null)
                _logger.LogException(te.getException(), TraceEventType.Error);
            else
                _logger.LogMessage(string.Format("Warning (JavaError) for {0}: {1}", _source, te.Message), TraceEventType.Warning);
        }
    }

before running the XsltTransformer, the ErrorListener of the transformer must be set.

    JavaErrorListener listener = new JavaErrorListener(Logger, sourcePath);
    transformer.Implementation.setErrorListener(listener);

Thats all! And it works really fine. Thanks a lot for the advice. And for the Saxon .Net API! :) I am really impressed about the features like creating my own .Net extensions and the listeners.