[[PageOutline]]

= Ping-Pong Example =

== Description ==
In this experiment, you will establish a communication protocol within a community. We use a middleware called '''LGI''' (Law-governed interaction) to implement and enforce the protocol. '''LGI''' is developed by [http://www.cs.rutgers.edu/~minsky/ Naftaly Minsky] of Rutgers University. For more information about '''LGI''', please refer to [http://www.moses.rutgers.edu/ here].

The protocol we want to establish is a message exchange protocol, at '''application level''', somewhat analogous to the '''flow control''' discipline of TCP/IP. We allow the exchange of two types of messages: '''ping''' messages, which might represent such things as a question, or a request; and '''pong''' messages, used as a reply to a previously received ping messages. The ping-pong policy regulates the flow of messages between any two actors x, y as follows: x cannot send any pong message to y unless y has previously sent a ping message to x; and x cannot send a second ping message to y unless y answers with a pong message to x following the initial ping.

== Work Flow ==
[[Image(acontroller-animate.gif, 30%, nolink)]] 
== Topology ==
[[Image(ping-pong-topology.png, 35%, nolink)]] 

== Tutorial Instructions ==
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<table id="Table_01" height="409" border="0" cellpadding="0" cellspacing="0">
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		<td>
			<a href="http://groups.geni.net/geni/wiki/JoeSandbox/PingPongExample/DesignSetup"><img src="http://groups.geni.net/geni/attachment/wiki/GENIExperimenter/Tutorials/Graphics/design.png?format=raw" width="152" height="152" alt="Design/Setup"></a>
               </td>
               <td>
<ul> 
             <li><a href="http://groups.geni.net/geni/wiki/JoeSandbox/PingPongExample/DesignSetup">Part I: Design/Setup</a></li>
             <ul>
                 <li> Lists of steps for setting up the example </li>
             </ul></ul>
               </td>
	</tr>
	<tr>
		<td>
			<a href="http://groups.geni.net/geni/wiki/JoeSandbox/PingPongExample/Execute"><img src="http://groups.geni.net/geni/attachment/wiki/GENIExperimenter/Tutorials/Graphics/execute.png?format=raw" width="152" height="143" alt="Execute"></a>
                </td>
		<td>
             <ul>
<li><a href="http://groups.geni.net/geni/wiki/JoeSandbox/PingPongExample/Execute">Part II: Execute</a></li>
             <ul> 
                 <li> Lists of steps for executing the example</li>
             </ul></ul>
                </td>
	</tr>
	<tr>
		<td>
			<a href="http://groups.geni.net/geni/wiki/JoeSandbox/PingPongExample/Finish"><img src="http://groups.geni.net/geni/attachment/wiki/GENIExperimenter/Tutorials/Graphics/finish.png?format=raw" width="152" height="114" alt="Finish"></a>
                </td>

		<td>
             <ul>
             <li><a href="http://groups.geni.net/geni/wiki/JoeSandbox/PingPongExample/Finish">Part III: Finish</a></li>
             <ul>
                 <li> Lists of steps for tearing down the example</li>
             </ul></ul>
                </td>

	</tr>
</table>

}}}