agentproxy.cs

Agent技术在智能交通中的应用

using System;
using System.Reflection;

namespace MobileAgents
{
	/// <summary>
	/// A sample implementation of an agent proxy class. A proxy class will
	/// help protect object references.
	/// </summary>
	[Serializable]
	public class AgentProxy
	{
		/// <summary>
		/// A weak reference to the agent object instance.
		/// </summary>
		private WeakReference _agent = null;

		/// <summary>
		/// Keeps track of whether or not the agent is still at this location or not.
		/// </summary>
		private bool _agentLeft = false;

		/// <summary>
		/// Internal Ctor.
		/// </summary>
		/// <param name="agentToProxy">The Agent to wrap.</param>
		internal AgentProxy(Agent agentToProxy)
		{
			_agent = new WeakReference(agentToProxy);
			agentToProxy.AgentMoved += new EventHandler(agentToProxy_AgentMoved);
		}

		/// <summary>
		/// Calls the wrapped Agent's Move method if the agent is still around.
		/// </summary>
		/// <param name="hostUrl">The url of the host to move to.</param>
		public void Move(string hostUrl)
		{
			if ((_agent.IsAlive) && (!_agentLeft))
			{
				Agent agent = (Agent)_agent.Target;
				agent.Move(hostUrl);
			}
			else
				throw new Exception("The agent no longer exists here.");
		}

		/// <summary>
		/// Invokes a member of the agent instance.
		/// </summary>
		/// <param name="memberName">The name of the member to invoke.</param>
		/// <param name="memberArguments">The arguments for the member</param>
		/// <returns>The return value (if any) resulting from invoking the member.</returns>
		public object InvokeMethod(string methodName, params object[] methodArguments)
		{
			if ((_agent.IsAlive) && (!_agentLeft))
			{
				Agent a = (Agent)_agent.Target;
				Type agentType = a.GetType();
				object retVal = agentType.InvokeMember(methodName, BindingFlags.Public | BindingFlags.InvokeMethod | BindingFlags.Instance, null, a, methodArguments);
				return retVal;
			}
			else
				throw new Exception("The agent no longer exists here.");
		}

		/// <summary>
		/// Handler for the wrapped Agent's AgentMoved event.  When the agent moves,
		/// don't let others contact it!
		/// </summary>
		/// <param name="sender">Sender of event.</param>
		/// <param name="e">Args of event.</param>
		private void agentToProxy_AgentMoved(object sender, EventArgs e) 
		{
			_agentLeft = true;
			_agent.Target = null;
		}
	}
}