EtCouchbaseClient client = clientFactory.getClient(couchHosts, getMandatoryString("bucket", message), password);
String fileId = getMandatoryString("files_id", message);
Number n = getMandatoryNumber("n", message);
String key = fileId + "!" + n;
client.asyncGet(key, new FutureCallback<Object>() {
@Override
public void onSuccess(Object o) {
message.reply((byte[]) o);
}