WCF中的动态ExpandoObject

Question

[尝试通过枚举类型的过程和动态数据操作来Ping / Pong我的服务。

[ServiceContract ( CallbackContract = typeof ( iStackoverflowCallBack ) )]
public interface iStackoverflow
{
    [OperationContract]
    void Ping ( Process Operation , dynamic Data );
}

[ServiceContract ( )]
public interface iStackoverflowCallBack
{
    [OperationContract]
    void Pong ( Process Operation , dynamic Data );
}

为什么该服务存在连接问题？

• 同时实现两个接口时，dynamic自动转换为object。
• 当从消费者ping提供我的服务时，ping根本无法到达该服务，但是该服务正常工作。

---

解决方案：

[DataContract]
public class SerializableDynamicObject : IDynamicMetaObjectProvider
{
    [DataMember]
    private IDictionary<string,object> dynamicProperties = new Dictionary<string,object>();

    #region IDynamicMetaObjectProvider implementation
    public DynamicMetaObject GetMetaObject (Expression expression)
    {
        return new SerializableDynamicMetaObject(expression, 
            BindingRestrictions.GetInstanceRestriction(expression, this), this);
    }
    #endregion

    #region Helper methods for dynamic meta object support
    internal object setValue(string name, object value) 
    {
        dynamicProperties.Add(name, value);
        return value;
    }

    internal object getValue(string name) 
    {
        object value;
        if(!dynamicProperties.TryGetValue(name, out value)) {
            value = null;
        }
        return value;
    }

    internal IEnumerable<string> getDynamicMemberNames() 
    {
        return dynamicProperties.Keys;
    }
    #endregion
}


public class SerializableDynamicMetaObject : DynamicMetaObject
{
    Type objType;

    public SerializableDynamicMetaObject(Expression expression, BindingRestrictions restrictions, object value) 
        : base(expression, restrictions, value) 
    {
        objType = value.GetType();
    }

    public override DynamicMetaObject BindGetMember (GetMemberBinder binder)
    {
        var self = this.Expression;
        var dynObj = (SerializableDynamicObject)this.Value;
        var keyExpr = Expression.Constant(binder.Name);
        var getMethod = objType.GetMethod("getValue", BindingFlags.NonPublic | BindingFlags.Instance);
        var target = Expression.Call(Expression.Convert(self, objType),
                                     getMethod,
                                     keyExpr);
        return new DynamicMetaObject(target,
            BindingRestrictions.GetTypeRestriction(self, objType));
    }

    public override DynamicMetaObject BindSetMember (SetMemberBinder binder, DynamicMetaObject value)
    {
        var self = this.Expression;
        var keyExpr = Expression.Constant(binder.Name); 
        var valueExpr = Expression.Convert(value.Expression, typeof(object));
        var setMethod = objType.GetMethod("setValue", BindingFlags.NonPublic | BindingFlags.Instance);
        var target = Expression.Call(Expression.Convert(self, objType),
        setMethod, 
        keyExpr, 
        valueExpr);
        return new DynamicMetaObject(target,
            BindingRestrictions.GetTypeRestriction(self, objType));
    }

    public override IEnumerable<string> GetDynamicMemberNames ()
    {
        var dynObj = (SerializableDynamicObject)this.Value;
        return dynObj.getDynamicMemberNames();
    }
}

Answer 1

任何WCF操作协定的参数必须是WCF数据协定（或原始类型），否则数据将不会序列化和传输。

http://msdn.microsoft.com/en-us/library/ms733127.aspx

Answer 2

详细介绍艾哈迈德提供的解决方案，如使用方法。

答案是从此页面获取的：https://loosexaml.wordpress.com/2011/01/01/wcf-serialization-of-dlr-dynamic-types/

[DataContract]
public class SerializableDynamicObject : IDynamicMetaObjectProvider
{
    [DataMember]
    private IDictionary<string,object> dynamicProperties = new Dictionary<string,object>();

    #region IDynamicMetaObjectProvider implementation
    public DynamicMetaObject GetMetaObject (Expression expression)
    {
        return new SerializableDynamicMetaObject(expression, 
            BindingRestrictions.GetInstanceRestriction(expression, this), this);
    }
    #endregion

    #region Helper methods for dynamic meta object support
    internal object setValue(string name, object value) 
    {
        dynamicProperties.Add(name, value);
        return value;
    }

    internal object getValue(string name) 
    {
        object value;
        if(!dynamicProperties.TryGetValue(name, out value)) {
            value = null;
        }
        return value;
    }

    internal IEnumerable<string> getDynamicMemberNames() 
    {
        return dynamicProperties.Keys;
    }
    #endregion
}


public class SerializableDynamicMetaObject : DynamicMetaObject
{
    Type objType;

    public SerializableDynamicMetaObject(Expression expression, BindingRestrictions restrictions, object value) 
        : base(expression, restrictions, value) 
    {
        objType = value.GetType();
    }

    public override DynamicMetaObject BindGetMember (GetMemberBinder binder)
    {
        var self = this.Expression;
        var dynObj = (SerializableDynamicObject)this.Value;
        var keyExpr = Expression.Constant(binder.Name);
        var getMethod = objType.GetMethod("getValue", BindingFlags.NonPublic | BindingFlags.Instance);
        var target = Expression.Call(Expression.Convert(self, objType),
                                     getMethod,
                                     keyExpr);
        return new DynamicMetaObject(target,
            BindingRestrictions.GetTypeRestriction(self, objType));
    }

    public override DynamicMetaObject BindSetMember (SetMemberBinder binder, DynamicMetaObject value)
    {
        var self = this.Expression;
        var keyExpr = Expression.Constant(binder.Name); 
        var valueExpr = Expression.Convert(value.Expression, typeof(object));
        var setMethod = objType.GetMethod("setValue", BindingFlags.NonPublic | BindingFlags.Instance);
        var target = Expression.Call(Expression.Convert(self, objType),
        setMethod, 
        keyExpr, 
        valueExpr);
        return new DynamicMetaObject(target,
            BindingRestrictions.GetTypeRestriction(self, objType));
    }

    public override IEnumerable<string> GetDynamicMemberNames ()
    {
        var dynObj = (SerializableDynamicObject)this.Value;
        return dynObj.getDynamicMemberNames();
    }
}

一种简单的使用方法：

dynamic d = new SerializableDynamicObject();
d.Name = “SomeData”;

d.Address = new SerializableDynamicObject();
d.Address.Line1 = “123 Spring St.”;

dynamic a = new SerializableDynamicObject();
a.Items = new List(new object[] { d, d });

return a;

但是请记住，WCF需要了解数据类型，因为它包含大多数最基本的数据类型，例如string，int等，所以这不是问题。但是，如果在动态对象中使用自定义数据类型，则必须使用[KnownType(typeof(XXX))]指令进行定义。这适用于enums，List<>和任何其他自定义类。

例如：

[KnownType(typeof(MyCustomEnum))]
[KnownType(typeof(List<object>))]
[DataContract]
public class SerializableDynamicObject : IDynamicMetaObjectProvider
...