http://bugswarm.net/docs/write-a-swarm-enabled-app

gistfile1.java

package earthquake_detector;
import java.util.Map;
import com.buglabs.bug.swarm.connector.pub.ISyncFilter;

/**
 * Given a previous sample and the current sample, determine if the difference is great enough to pass data to the server.
 *
 */
public class AccelerometerSampleFilter implements ISyncFilter {

	private float lx, ly, lz;
	
	public AccelerometerSampleFilter() {
		lx = 0;
		ly = 0;
		lz = 0;
	}
	
	@Override
	public boolean synchronize(Map model, Object[] keys) {
		boolean retVal = false;
		
		float nx = (Float) model.get("x");
		float ny = (Float) model.get("y");
		float nz = (Float) model.get("z");
		
		if (deviates(lx, nx, 1) || deviates(ly, ny, 1) || deviates(lz, nz, 1)) {
			retVal = true;
		}
		
		lx = nx;
		ly = ny;
		lz = nz;
		
		return retVal;
	}
	
	private boolean deviates(float src, float target, float delta) {
		return Math.abs(src - target) > delta;
	}
}