protected function _getManifest( $filepath )
	{
		if( !file_exists( $filepath ) ) {
			throw new MW_Jsb2_Exception( sprintf( 'File does not exists: "%1$s"', $filepath ) );
		}

		if( ( $content = file_get_contents( $filepath ) ) === false ) {
			throw new MW_Jsb2_Exception( sprintf( 'Unable to read content from "%1$s"', $filepath ) );
		}

		if( ( $content = json_decode( $content ) ) === null ) {
			throw new MW_Jsb2_Exception( 'File content is not JSON encoded' );
		}

		return $content;
	}