def wf_string?(str)
      #
      # Only allows PCRE "word" characters, spaces, full-stops and
      # commas in tags and descriptions. This might be too restrictive,
      # but if it is, this is the only place we need to change it.
      #
      if str.is_a?(String) && str.size < 1024 && str =~ /^[\-\w \.,]*$/
        return true
      end

      raise Wavefront::Exception::InvalidString
    end
def wf_string?(str)
      #
      # Only allows PCRE "word" characters, spaces, full-stops and
      # commas in tags and descriptions. This might be too restrictive,
      # but if it is, this is the only place we need to change it.
      #
      if str.is_a?(String) && str.size < 1024 && str =~ /^[\-\w \.,]*$/
        return true
      end

      raise Wavefront::Exception::InvalidString
    end
Ensure the given argument is a valid string, for a tag name.

 @param str [String] the string name to validate
 @return True if the string is valid
 @raise Wavefront::Exception::InvalidString if string is not valid.