Topology Starter

To start a topology, users must create a class which should implement TopologyStarter interface. Following is the interface code.

package samoa.core;

/**
 * Topology stater interface
 */
public interface TopologyStarter extends java.io.Serializable{
	/**
	 * Start the topology.
	 */
	void start();
}

In void start() method, users should call a function of there EntrancePI which brings next message/tuple from the external source, in a loop. Following is an example of a class implementing TopologyStarter interface.

package samoa.fpm;

import samoa.core.Processor;
import samoa.core.TopologyStarter;
import samoa.fpm.processors.StreamSourceP;

public class MyTopologyStarter implements TopologyStarter {

	private StreamSourceProcessor streamSource;
	
	public MyTopologyStarter(StreamSourceProcessor s)
	{
		this.streamSource = s;
	}
	
	@Override
	public void start() {
		while(true)
		streamSource.nextTuple();
	}

}

SAMOA calls the start() method of the Topology Starter class once in the beginning to start the topology. In the above code snippet, nextTuple() method of an EntranceProcessingItem is called in a loop which continuously brings external tuples/messages to the topology for processing.