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sending xml message in a java udp packet

I'm trying to send an xml message to a Java SAX parser listening on a UDP port.
When I send a message the parser it gives the error message

[Fatal Error] :1:1 Content is not allowed in prolog.

I've reduced my UDP packet to just the prolog and I still get the error

Here is what I'm sending

String xmlMsg = new String("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");

byte buffer[] = xmlMsg.getBytes();
DatagramSocket sndSocket = new DatagramSocket();
sndSocket.send(new DatagramPacket(buffer,buffer.length,InetAddress.getByName("127.0.0.1"),Integer.parseInt("3031")));

I want to find out what I'm doing wrong and how do I send an XML message in a UDP packet that the SAX parser will accept?

CEHJ

>> [Fatal Error] :1:1 Content is not allowed in prolog.

That sounds more like an error with reading xml, not writing it. At what point are you getting that message

mitchguy

ASKER

The reader is doing this

DatagramPacket incomingPacket = new DatagramPacket(buffer,buffer.length);
listenSocket.receive(incomingPacket);
byte data[] = incomingPacket.getData();
InputSource source = new InputSource(new StringReader(data.toString()));
fromXML(source);

private synchronized fromXML(InputSource in) throws Exception
{
XMLReader xr;
xr.setContentHandler(this);
xr.parse(in);
}

CEHJ

>>InputSource source = new InputSource(new StringReader(data.toString()));

should be as below

InputSource source = new InputSource(new StringReader(new String(data)));

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mitchguy

ASKER

I'm not sure I understand the difference between data.toString() and new String(data) ?

I made the change and ran it again I get this error listed below still

[Fatal Error] :1:39: Content is not allowed in prolog.
org.xml.sax.SAXParseException: Content is not allowed in prolog

Which is actually a little different than before, the difference being
before the numbers after [Fatal Error] were 1:1 and now it is 1:39
The size of the message is 38 maybe I have some sort of missing character
that is supposed to be at the end of the data for the parser?

CEHJ

Well byte[] doesn't have a toString method that will be of any use to you. Can you instead do this and tell us what gets printed?

String s = new String(data);
System.out.println(data);
InputSource source = new InputSource(new StringReader(s));

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mitchguy

ASKER

The output is certainly not what I expected

[B@1113708

Since I'm sending and receiving on the same machine it shouldn't be a byte swap problem right?

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CEHJ

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mitchguy

ASKER

If I do this
String myString = new String(incomingPacket.getData());
The output is
<?xml version="1.0" encoding="UTF-8"?>

However after that I did
InputSource source = new InputSource(new StringReader(myString));

and unfortunately still got the error
[Fatal Error] :1:39: Content is not allowed in prolog.
org.xml.sax.SAXParseException: Content is not allowed in prolog

CEHJ

Well of course your software is expecting to parse a document. 'myString' is just a header. You need the rest of the doc in there too

mitchguy

ASKER

That did the Trick:)
Thanks!

CEHJ

:-)