C＃客户端服务器对象列表转换错误

Question

I am developing a client server application in C#.

I am sending from my server to client an List of Students objects which I serialize on the server side and deserialize on client side. The serialization and deserialization are as follows :

// server side serialization.
List<Student> ordByMedGen = repo.ordByMedGen();
BinaryFormatter binaryFormatter = new BinaryFormatter();
binaryFormatter.Serialize(writer.BaseStream, ordByMedGen);

// client side deserialization.
BinaryFormatter bin = new BinaryFormatter();
List<Student> list = (List<Student>)bin.Deserialize(receive.BaseStream);
Console.WriteLine(list.Count);
// print the list

Using this method I succesfully send a List of Strings from server side and printed on the client side. When I tried with my Student class I got the following error

[A]System.Collections.Generic.List 1[ServerClient.Student] cannot be cast to [B]System.Collections.Generic.List 1[ServerClient.Student]. Type A originates from 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'LoadNeither' at location 'C:\\Windows\\Microsoft.Net\\assembly\\GAC_64\\mscorlib\\v4.0_4.0.0.0__b77a5c561934e089\\mscorlib.dll'. Type B originates from 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'LoadNeither' at location 'C:\\Windows\\Microsoft.Net\\assembly\\GAC_64\\mscorlib\\v4.0_4.0.0.0__b77a5c561934e089\\mscorlib.dll'.

To create the Server.exe and Client.exe I used the following commands:

C:\Windows\Microsoft.NET\Framework\v4.0.30319\csc.exe Server.cs Repository.cs Student.cs
C:\Windows\Microsoft.NET\Framework\v4.0.30319\csc.exe Client.cs Student.cs

and I get no errors or warning. Also my Student class have the [Serialization] attribute. I did searched the web for this kind of errors but i couldn't find anything usefull.

Later Edit: Maybe at compilation the fact that Student.cs is provided as a reference both on Server and Client somehow confuse the compiler and sees Student as 2 different types as in error: A and B ?

Later Edit(2): This problem can be also solved by creating at compilation an dll for Student.cs and referenced on server and client, so the compiler doesen't get confused.

Answer 1

It sounds like you have two different assemblies - one at the client, one on the server - contributing this type. Types are defined by their assembly, and even if identical: are not interchangeable. Basically, BinaryFormatter will fight you every step of the way here. My advice: don't use BinaryFormatter. Most other serializers (XmlSerializer, json.jet, jil, DataContractSerializer, protobuf-net etc) will work perfectly fine in your scenario, and will not complain at all.