public class StudentMng
    {
        StudentContractClient client;

        public StudentMng()
        {
            client = new StudentContractClient();
        }

        ~StudentMng()
        {
            client.Close();
        }

        public void Add(Student entity)
        {
            client.Add(entity);
        }
        public Student GetByID(int id)
        {
            return client.GetByID(id);
        }

        public void DeleteByID(int id)
        {
            client.DeleteByID(id);
        }

        public void Update(Student entity)
        {
            client.Update(entity);
        }
    }

using(SoapClient client = new SoapClient())
{
    client.Add(entity);
}

------解决方案--------------------

不用封装呀，可以实现WCF 拦截器的。

http://blog.csdn.net/fangxinggood/article/details/6144893