public static  void validate(Compiler compiler,
    Node.Nodes page) throws JasperException 
{
        /*
         * Visit the page/tag directives first, as they are global to the page
         * and are position independent.
         */
        page.visit(new DirectiveVisitor(compiler));
        // Determine the default output content type
        PageInfo pageInfo = compiler.getPageInfo();
        String contentType = pageInfo.getContentType();
        if (contentType == null || contentType.indexOf("charset=") <  0) {
            boolean isXml = page.getRoot().isXmlSyntax();
            String defaultType;
            if (contentType == null) {
                defaultType = isXml ? "text/xml" : "text/html";
            } else {
                defaultType = contentType;
            }
            String charset = null;
            if (isXml) {
                charset = "UTF-8";
            } else {
                if (!page.getRoot().isDefaultPageEncoding()) {
                    charset = page.getRoot().getPageEncoding();
                }
            }
            if (charset != null) {
                pageInfo.setContentType(defaultType + ";charset=" + charset);
            } else {
                pageInfo.setContentType(defaultType);
            }
        }
        /*
         * Validate all other nodes. This validation step includes checking a
         * custom tag's mandatory and optional attributes against information in
         * the TLD (first validation step for custom tags according to
         * JSP.10.5).
         */
        page.visit(new ValidateVisitor(compiler));
        /*
         * Invoke TagLibraryValidator classes of all imported tags (second
         * validation step for custom tags according to JSP.10.5).
         */
        validateXmlView(new PageDataImpl(page, compiler), compiler);
        /*
         * Invoke TagExtraInfo method isValid() for all imported tags (third
         * validation step for custom tags according to JSP.10.5).
         */
        page.visit(new TagExtraInfoVisitor(compiler));
}