/**
  * Walk the XML tree and validate all nodes.
  *
  * @param received
  * @param source
  * @param validationContext
  */
 private void validateXmlTree(
     Node received,
     Node source,
     XmlMessageValidationContext validationContext,
     NamespaceContext namespaceContext,
     TestContext context) {
   switch (received.getNodeType()) {
     case Node.DOCUMENT_TYPE_NODE:
       doDocumentTypeDefinition(received, source, validationContext, namespaceContext, context);
       break;
     case Node.DOCUMENT_NODE:
       validateXmlTree(
           received.getFirstChild(),
           source.getFirstChild(),
           validationContext,
           namespaceContext,
           context);
       break;
     case Node.ELEMENT_NODE:
       doElement(received, source, validationContext, namespaceContext, context);
       break;
     case Node.TEXT_NODE:
     case Node.CDATA_SECTION_NODE:
       doText(received, source);
       break;
     case Node.ATTRIBUTE_NODE:
       throw new IllegalStateException();
     case Node.COMMENT_NODE:
       doComment(received);
       break;
     case Node.PROCESSING_INSTRUCTION_NODE:
       doPI(received);
       break;
   }
 }
  /**
   * Checks whether the given node contains a validation matcher
   *
   * @param node
   * @return true if node value contains validation matcher, false if not
   */
  private boolean isValidationMatcherExpression(Node node) {
    switch (node.getNodeType()) {
      case Node.ELEMENT_NODE:
        return node.getFirstChild() != null
            && StringUtils.hasText(node.getFirstChild().getNodeValue())
            && ValidationMatcherUtils.isValidationMatcherExpression(
                node.getFirstChild().getNodeValue().trim());

      case Node.ATTRIBUTE_NODE:
        return StringUtils.hasText(node.getNodeValue())
            && ValidationMatcherUtils.isValidationMatcherExpression(node.getNodeValue().trim());

      default:
        return false; // validation matchers makes no sense
    }
  }
  /**
   * Handle element node.
   *
   * @param received
   * @param source
   * @param validationContext
   */
  private void doElement(
      Node received,
      Node source,
      XmlMessageValidationContext validationContext,
      NamespaceContext namespaceContext,
      TestContext context) {

    doElementNameValidation(received, source);

    doElementNamespaceValidation(received, source);

    // check if element is ignored either by xpath or by ignore placeholder in source message
    if (XmlValidationUtils.isElementIgnored(
        source, received, validationContext.getIgnoreExpressions(), namespaceContext)) {
      return;
    }

    // work on attributes
    if (log.isDebugEnabled()) {
      log.debug("Validating attributes for element: " + received.getLocalName());
    }
    NamedNodeMap receivedAttr = received.getAttributes();
    NamedNodeMap sourceAttr = source.getAttributes();

    Assert.isTrue(
        countAttributes(receivedAttr) == countAttributes(sourceAttr),
        ValidationUtils.buildValueMismatchErrorMessage(
            "Number of attributes not equal for element '" + received.getLocalName() + "'",
            countAttributes(sourceAttr),
            countAttributes(receivedAttr)));

    for (int i = 0; i < receivedAttr.getLength(); i++) {
      doAttribute(
          received, receivedAttr.item(i), source, validationContext, namespaceContext, context);
    }

    // check if validation matcher on element is specified
    if (isValidationMatcherExpression(source)) {
      ValidationMatcherUtils.resolveValidationMatcher(
          source.getNodeName(),
          received.getFirstChild().getNodeValue().trim(),
          source.getFirstChild().getNodeValue().trim(),
          context);
      return;
    }

    // work on child nodes
    NodeList receivedChilds = received.getChildNodes();
    NodeList sourceChilds = source.getChildNodes();

    Assert.isTrue(
        receivedChilds.getLength() == sourceChilds.getLength(),
        ValidationUtils.buildValueMismatchErrorMessage(
            "Number of child elements not equal for element '" + received.getLocalName() + "'",
            sourceChilds.getLength(),
            receivedChilds.getLength()));

    for (int i = 0; i < receivedChilds.getLength(); i++) {
      this.validateXmlTree(
          receivedChilds.item(i),
          sourceChilds.item(i),
          validationContext,
          namespaceContext,
          context);
    }

    if (log.isDebugEnabled()) {
      log.debug(
          "Validation successful for element: "
              + received.getLocalName()
              + " ("
              + received.getNamespaceURI()
              + ")");
    }
  }