C# Serialize() 抛出System.Runtime.Serialization.SerializationException

因为要往socket发送数据，需要把instance序列化(Serialization)，用下面的函数发现会抛出SerializationException，Exception thrown: 'System.Runtime.Serialization.SerializationException' in mscorlib.dll.

        ///<summary>         /// 序列化         /// </summary>         /// <param name="data">要序列化的对象</param>         /// <returns>返回存放序列化后的数据缓冲区</returns>         public static byte[] Serialize(object data)        {            BinaryFormatter formatter = new BinaryFormatter();            MemoryStream mems = new MemoryStream();            formatter.Serialize(mems, data);            return mems.GetBuffer();        }
class定义与序列化调用代码如下：
        class FeedbackObj        {            public FeedbackObj() { }            public string mUserName;            public int mUserId;            public string mContent;            public string mEmail;        }  
        byte[] buff = new byte[1024];        FeedbackObj fb = new FeedbackObj();        fb.mUserId = 1234;        fb.mUserName = "YOUQ";        fb.mContent = sendMessage;        fb.mEmail = "Youqi.Cai@xxx.com";        buff = Serialize(fb); 
查阅MSDN发现原来是需要序列化的class的定义需要mark it with the Serializable attribute。
[Serializable]public class MyObject {  public int n1 = 0;  public int n2 = 0;  public String str = null;}
附上MSDN关于序列化的几点建议大致意思：
确定一个class是否要定义为serializable 应该思考几个问题：该类是否有夸应用程序使用的需求？是否可能被远程使用(通过socket发送? By Youqi.)？该类的派生类是否有可能需要被序列化呢？等等。如果不确定就建议用serializable修饰，除非有以下下情况：
2.如果包含只有在当前这一个实例中有效的特殊的成员（unmanaged memory or file handles），可用NonSerialized 修饰，实例化过程中将忽略该元素；
3.如果类中数据成员包含敏感信息，需要有选择性的对成员进行序列化，建议implement ISerializable 来实现，做法更灵活。
原文如下：
Serialization Guidelines
You should consider serialization when designing new classes since a class cannot be made serializable after it has been compiled. Some questions to ask are: Do I have to send this class across application domains? Will this class ever be used with remoting? What will my users do with this class? Maybe they derive a new class from mine that needs to be serialized. When in doubt, mark the class as serializable. It is PRobably better to mark all classes as serializable unless:
They will never cross an application domain. If serialization is not required and the class needs to cross an application domain, derive the class from MarshalByRefObject.The class stores special pointers that are only applicable to the current instance of the class. If a class contains unmanaged memory or file handles, for example, ensure these fields are marked as NonSerialized or don't serialize the class at all.Some of the data members contain sensitive information. In this case, it will probably be advisable to implement ISerializable and serialize only the required fields.