nodehandle.java

p2p仿真器。开发者可以工作在覆盖层中进行创造和测试逻辑算法或者创建和测试新的服务。PlanetSim还可以将仿真代码平稳转换为在Internet上的实验代码

package planet.commonapi;

/**
 * This interface is an abstraction of a node handle from the CommonAPI paper. A
 * node handle is a handle to a known node, which conceptually includes the
 * node's Id, as well as the node's underlying network address (such as IP/port).
 *
 * @author <a href="mailto: [e-mail]">Jordi Pujol</a>
 * 07-jul-2005
 */
public abstract class NodeHandle  extends java.util.Observable implements java.io.Serializable {
	
	//constants defining types of observable events
	public static final Integer PROXIMITY_CHANGED = new Integer(1);
	public static final Integer DECLARED_DEAD = new Integer(2);
	public static final Integer DECLARED_LIVE = new Integer(3);
	
	/**
	 * Returns this node's id.
     *
     * @return The corresponding node's id.  
	 */
	public abstract Id getId();
	
	/**
	 * Returns whether or not this node is currently alive
	 *
	 * @return Whether or not this node is currently alive
	 */ 
	public abstract boolean isAlive();
	
	/**
	 * Updates the alive flag.
	 * @param alive New value for the alive flag.
	 */
	public abstract void setAlive(boolean alive);
	
	/**
	 * Evaluates the proximity between the node who invokes this method,
	 * and the node that represents this NodeHandle.
	 * @return The proximity between the two nodes, who invokes and 
	 * the node represented by this NodeHandle.
	 */
	public abstract int getProximity();
    
    /**
     * Sets the new Id for this NodeHandle, and the flag 'alive' to true.
     * @param newValue The new Id
     * @return The same instance, after being updated.
     */
    public abstract NodeHandle setValues(Id newValue);
    
    /**
     * Sets the new Id for this NodeHandle, and the flag 'alive' to the
     * specified value.
     * @param newValue The new Id
     * @param alive true if the NodeHandle is alive.
     * @return The same instance, after being updated.     
     */
    public abstract NodeHandle setValues(Id newValue, boolean alive);
	
}