Question

我有一个传输应用程序，它用作pub- / sub服务器在客户端之间中继数据。 pub- / sub服务器只需要了解一些数据，例如它需要topicname能够将已发布的主题转发给正确的订阅者。

为了达到这个目的，我想到了一个方案，其中一个被装饰为ProtoContract的类包含一个byte []，而byte []又包含protobuf-net序列化数据。通过这种方式，服务器只需要对其中继的数据的一小部分进行反序列化（并且不需要知道类型）。我的类型看起来像这样;

[ProtoContract]
public class DataFrame
{
    /// <summary>
    /// Time the data was issued or sampled. In UTC time.
    /// </summary>
    [ProtoMember(1)]
    public DateTime TimeStamp = DateTime.UtcNow;

    /// <summary>
    /// The topic associated with the data
    /// </summary>
    [ProtoMember(2)]
    public string TopicName = string.Empty;

    /// <summary>
    /// Command, can be either Discover, Subscribe, Unsubscribe or Publish
    /// </summary>
    [ProtoMember(3)]
    public string Command = string.Empty;

    /// <summary>
    /// The fully qualified type name of the content
    /// </summary>
    [ProtoMember(4)]
    private string _typeName = string.Empty;

    /// <summary>
    /// Serialized content data (if any)
    /// </summary>
    [ProtoMember(5)]
    private byte[] _content;

    /// <summary>
    /// The fully qualified type name of the content
    /// </summary>
    public string TypeName
    {
        get
        {
            return _typeName;
        }
    }

    /// <summary>
    /// Get the content of this DataFrame
    /// </summary>
    /// <typeparam name="T">Type of the content</typeparam>
    /// <returns>The content</returns>
    public T GetContent<T>()
    {
        MemoryStream ms = new MemoryStream(_content);
        return Serializer.DeserializeWithLengthPrefix<T>(ms, PrefixStyle.Base128);
    }

    /// <summary>
    /// Set the content for this DataFrame
    /// </summary>
    /// <param name="value">The content to set, must be serializable and decorated as a protobuf contract type</param>
    public void SetContent<T>(T value)
    {
        MemoryStream ms = new MemoryStream();
        Serializer.SerializeWithLengthPrefix(ms, value, PrefixStyle.Base128);
        _content = ms.GetBuffer();
        _typeName = value.GetType().AssemblyQualifiedName;
    }

    /// <summary>
    /// Encode the frame to a serialized byte array suitable for tranmission over a network
    /// </summary>
    /// <returns>The encoded byte[]</returns>
    public byte[] Encode()
    {
        DataFrame frame = (DataFrame)this;
        MemoryStream ms = new MemoryStream();
        Serializer.SerializeWithLengthPrefix(ms, frame, PrefixStyle.Base128);
        return ms.GetBuffer();
    }

    /// <summary>
    /// Factory function to create a frame from a byte array that has been received
    /// </summary>
    /// <param name="buffer">The serialized data to decode</param>
    /// <returns>A new dataframe decoded from the byte[]</returns>
    public static DataFrame Decode(byte[] buffer)
    {
        MemoryStream ms = new MemoryStream(buffer);
        DataFrame frame = Serializer.DeserializeWithLengthPrefix<DataFrame>(ms, PrefixStyle.Base128);
        frame._timeStamp = DateTime.SpecifyKind(frame._timeStamp, DateTimeKind.Utc);
        return frame;
    }
}

问题是，我能够反序列化DataFrame，但是当反序列化有效负载byte []时，我得到了protobuf异常。也就是说，这是有效的（服务器是UdpClient）;

data = server.Receive(ref remoteEP);
DataFrame frame = DataFrame.Decode(data);

但即使内容是字符串，这也会给我一个protobuf异常;

string content = frame.GetContent<string>();

有没有人对我做错了什么有任何指示？

带有序列化byte []成员的Protobuf-net

0 个答案: