* @return 0, if no differences are found, otherwise a positive number
* indicating the number of differences.
* @throws java.io.IOException an this occurs while reading
*/
public int compare() throws java.io.IOException {
XMLFileReader reader1 = new XMLFileReader(_file1);
XMLNode node1 = reader1.read();
XMLFileReader reader2 = new XMLFileReader(_file2);
XMLNode node2 = reader2.read();
return compareNodes(node1, node2);
}