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    <p>You can't detect the type in isolation, since the protobuf spec doesn't add any data to the stream for this; however, there are a number of ways of making this easy, depending on the context:</p> <ul> <li>a union type (as mentioned by Jon) covers a range of scenarios</li> <li>inheritance (protobuf-net specific) can be versatile - you can have a base-message type, and any number of concrete message types</li> <li>you can use a prefix to indicate the incoming type</li> </ul> <p>the last approach is actually very valuable in the case of raw TCP streams; this is <em>on the wire</em> identical to the union type, but with a different implementation; by deciding in advance that 1=Foo, 2=Bar etc (exactly as you do for the union type approach), you can use <code>SerializeWithLengthPrefix</code> to write (specifying the 1/2/etc as the field number), and the non-generic <code>TryDeserializeWithLengthPrefix</code> to read (this is under Serializer.NonGeneric in the v1 API, or on the TypeModel in the v2 API), you can provide a type-map that resolves the numbers back to types, and hence deserialize the correct type. And to pre-empt the question "why is this useful with TCP streams?" - because: in an ongoing TCP stream you <strong>need</strong> to use the <code>WithLengthPrefix</code> methods <strong>anyway</strong>, to avoid over-reading the stream; so you might as well get the type identifier for free!</p> <p>summary:</p> <ul> <li>union type: easy to implement; only down side is having to then check which of the properties is non-null</li> <li>inheritance: easy to implement; can use polymorphism or discriminator to handle "what now?"</li> <li>type prefix: a bit more fiddly to implement, but allows more flexibility, and has zero overhead on TCP streams</li> </ul>
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    1. COHi thanks for the detailed reply. I've managed to accomplish the desired result using Serializer.SerializeWithLengthPrefix & Serializer.NonGeneric.TryDeserializeWithLengthPrefix I would like to use the RuntimeTypeModel to avoid having attributes on my classes. The model.SerializeWithLengthPrefix seems to work as expected but I could not find an equivallent of TryDeserializeWithLengthPrefix on the RuntimeTypeModel. The model.DeserializeWithLengthPrefix seems to expect a type. How should I accomplish the equivalent of TryDeserializeWithLengthPrefix using the model. Using version 2.0.0.480 nuget
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      1. USYavor Shahpasov
    2. COI've changed my code to add to add model definitions to RuntimeTypeModel.Default and I can use the TryDeserializeWithLengthPrefix without attributes. Before I was creating a new model using TypeModel.Create So problem solved Thanks
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    3. CO@Yavor on TypeModel, it is just DeserializeWithLengthPrefix, along with a TypeResolver. Not sure where the Try went! I'll look for it behind the cushions on the sofa - that is where most things end up.
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