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    <p>MEF will definitely help you, but not only it. You have to use the <a href="http://msdn.microsoft.com/en-us/library/system.runtime.serialization.iserializationsurrogate.aspx" rel="nofollow">ISerializationSurrogate</a>. Most of the explanations for the below you can find <a href="http://msdn.microsoft.com/en-us/library/system.runtime.serialization.surrogateselector.aspx" rel="nofollow">here</a>.</p> <p>So, given the following definition for the packet interface:</p> <pre><code>public interface IPacket { string GetInfo(); } </code></pre> <p>You have the following implementations, residing in their own assembly:</p> <pre><code>[Export(typeof(IPacket))] class FirstPacket : IPacket { public FirstPacket() { Name = "Joe"; } public string Name { get; set; } public string GetInfo() { return "Name: " + Name; } } [Export(typeof(IPacket))] class SecondPacket : IPacket { public SecondPacket() { Measurement = 42.42m; } public decimal Measurement { get; set; } public string GetInfo() { return "Measurement: " + Measurement; } } </code></pre> <p>Now we will define another interface, something like:</p> <pre><code>public interface IPacketSurrogateProvider { void AddSurrogate(SurrogateSelector toSelector); } </code></pre> <p>And the matching implementations, in the same assembly where concrete packets are defined:</p> <pre><code>[Export(typeof(IPacketSurrogateProvider))] class FirstPacketSurrogateProvider : IPacketSurrogateProvider, ISerializationSurrogate { public void AddSurrogate(SurrogateSelector toSelector) { toSelector.AddSurrogate(typeof(FirstPacket), new StreamingContext(StreamingContextStates.All), this); } public void GetObjectData(object obj, SerializationInfo info, StreamingContext context) { info.AddValue("Name", ((FirstPacket)obj).Name); } public object SetObjectData(object obj, SerializationInfo info, StreamingContext context, ISurrogateSelector selector) { ((FirstPacket)obj).Name = info.GetString("Name"); return obj; } } [Export(typeof(IPacketSurrogateProvider))] class SecondPacketSurrogateProvider : IPacketSurrogateProvider, ISerializationSurrogate { public void AddSurrogate(SurrogateSelector toSelector) { toSelector.AddSurrogate(typeof(SecondPacket), new StreamingContext(StreamingContextStates.All), this); } public void GetObjectData(object obj, SerializationInfo info, StreamingContext context) { info.AddValue("Measurement", ((SecondPacket)obj).Measurement); } public object SetObjectData(object obj, SerializationInfo info, StreamingContext context, ISurrogateSelector selector) { ((SecondPacket)obj).Measurement = info.GetDecimal("Measurement"); return obj; } } </code></pre> <p>And now, in an assembly which does have reference to the one with the interfaces, but not to the one with the implementations, and having the same deployment folder as both of the above:</p> <pre><code>public static void Test() { var container = new CompositionContainer(new DirectoryCatalog(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location))); var packets = container.GetExportedValues&lt;IPacket&gt;().ToArray(); var packetSurrogateProviders = container.GetExportedValues&lt;IPacketSurrogateProvider&gt;(); var surrogateSelector = new SurrogateSelector(); foreach (var provider in packetSurrogateProviders) { provider.AddSurrogate(surrogateSelector); } var deserializedPackets = new IPacket[] { }; using (var stream = new MemoryStream()) { var formatter = new BinaryFormatter {SurrogateSelector = surrogateSelector}; formatter.Serialize(stream, packets); stream.Position = 0; deserializedPackets = (IPacket[])formatter.Deserialize(stream); } foreach (var packet in deserializedPackets) { Console.WriteLine("Packet info: {0}", packet.GetInfo()); } } </code></pre> <p>Which produces:</p> <blockquote> <p>Packet info: Name: Joe</p> <p>Packet info: Measurement: 42.42</p> </blockquote>
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    1. COThank you for your answer, but I have some questions.
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    2. COThank you for your answer, but I have some questions. Why do I need that surrogate class? I could use mef to load all IPackets into a list of IPacket without it and I'm pretty sure that my program would then recognize them.. I just thought that since I don't actually need them in a list, I would just let my program recognize them somehow during runtime.. It seems to me that it should be much simpler, I have the path and can Load the assembly, it shouldn't require so much effort..
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    3. COYou have to understand that exporting/loading the packets through MEF in my example is just for the sake of convenience. I could also serialize the packets from inside their own assembly and then deserialize on the receiving side, without adding reference. Your problem is not to recognize the type, because, as I understand, it's enough that you have the IPacket interface. Your problem is making the BinaryFormatter recognize the type, and that's what the surrogates are for. Another question is why don't you use WCF for communication?
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