protected function checkUpload()
    {
        //no upload field defined for uploaded field
        if(!isset($this->uploadFields[$this->uploadedField])) {
            $this->uploadMessages[] = sprintf('No definition set for POST uploadField field "%s"', $this->uploadedField);
            return false;
        }
        //no processing method implemented for any of outputs
        foreach($this->uploadFieldsDefinitions[$this->uploadedField]['outputs'] as $output => $outputDefinition) {
            if(isset($outputDefinition['processor'])) {
                if(!method_exists($this, $outputDefinition['processor'])) {
                    $this->uploadMessages[] = sprintf('Class <b>%s</b> must define method <b>%s</b> to process output <b>%s</b> of upload field <b>%s</b>', $this->name, $outputDefinition['processor'], $output, $this->uploadedField);
                    return false;
                }
            }
        }
        return true;
    }