function headObject(params, callback) {
    submitRequest.call(this, {
        Action: 'name/cos:HeadObject',
        method: 'HEAD',
        Bucket: params.Bucket,
        Region: params.Region,
        Key: params.Key,
        VersionId: params.VersionId,
        headers: params.Headers,
    }, function (err, data) {
        if (err) {
            var statusCode = err.statusCode;
            if (params.Headers['If-Modified-Since'] && statusCode && statusCode === 304) {
                return callback(null, {
                    NotModified: true,
                    statusCode: statusCode,
                });
            }
            return callback(err);
        }
        if (data.headers && data.headers.etag) {
            data.ETag = data.headers && data.headers.etag;
        }
        callback(null, data);
    });
}