====== ReplayServer ======


The ReplayServer is a core server to provide Group messages history in the SDDL [[architecture|Middleware]]. He is capable to listen Topics saving their messages and retransmit then when solicited. It extends the pub/sub model in a perspective that a MobileNode or a DDS core server can recover past messages and connect or reconnect.  Moreover, it can replay messages sent for all clients or each specific group! 


===== ReplayServer Architecture =====
As a core server the ReplayServer must be placed inside the SDDL core network as displayed below:

{{ :replayserver01.jpg?300 |}}

It works with a listener that subscriber the [[hellogroup|Message and PrivateMessage]] SDDL topics in order receives all messages and save the selected in a DBMS (MySQL). Then anytime a client or another core server need some messages from a specific moment in the past. 

===== ReplayServer Usage =====

It was configured to be used by any application witch transport an String as a payload. To use the ReplayServer you must follow the steps below:

1) Download it from [[here]].

2) Make sure that you have the MySQL running with the db provided.

3) Provide the config parameters inside the file configurations.txt.

4) Run it!

It´s done.

To retrieve the messages you can easily test it by altering the [[hellomobile|connected method]] in any SDDL example as bellow:
<file java ClientTest.java>
  @Override

  public void connected(NodeConnection remoteCon) {
    ApplicationMessage message = null;
    message = new ApplicationMessage();
    ResquestType serializableContent = new ResquestType();
    serializableContent.fromPeriod = "2013-10-21 01:00:00"; // From when you desire the messages ...

    serializableContent.type = "gmessage"; // Specifying the kind of message, this is the default kind.
    serializableContent.group = 2; // GroupDefiner group code or -1 for messages sent for all clients.
    
    message.setContentObject(serializableContent);
    try {
      remoteCon.sendMessage(message);
    
}
    catch (IOException e) {
      e.printStackTrace();
    }
  }
</file> 

If you desire use other payloads or your own message type, you must include then in the [[hellocore|onNewData method a provide your processMessageTopic]]. You can easy inspect the code and reuse the extra samples.
==== Disclamer ====
This was done as the first contact with the SDDL middleware and the Pub/Sub paradigm. 

You can freely use this service and ask if you need some help:

Bruno Olivieri - bruno@olivieri.com.br