How to properly migrate from WCF DatacontractSerializer to Protobuf-net?

Question

We have a huge application with a lot of classes. We are currently porting this .net application to IPad with Monotouch. We have some problems with the DataContractSerializer and we would like to use Marc Gravell's protobuf-net serializer.

The communication between the client and the server is managed by a WCF Service.

A WCF service is made of one Interface exposed to the client and the server, and one implementation of this interface on the server.

The interface looks like that:

[ServiceContract]
public interface IMyService
{
    [OperationContract]
    SomeObject MyFunction(SomeObject myObject);
}

The server side implementation looks like that:

[ServiceBehavior(...)]
public class MyService
{
    public SomeObject MyFunction(SomeObject myObject)
    {
    }
}

Our classes looks like that:

[DataContract]
public class MyClass
{
    [DataMember]
    public int SomeProp {get; set;}

    [OnSerialized]
    public void OnSerialized(StreamingContext context)
    {
    }
}

So here are my questions:

What would be the changes to do to my classes, wcf interface and wcf implementation.
How would I replace the default WCF DataContractSerializer to the Protobuf Serializer.

Please note that on monotouch, I only have access to Protobuf and Protobuf.Meta namespaces.

[EDIT] I found a way to swap the serializer runtime: Custom WCF DataContractSerializer

The above solution uses the DataContractSerializerOperationBehavior. Does Protobuf-net provides such behavior?

Second what Marc said: don't assume that just because you can swap out the serializer on MS .NET that you can do it in Mono, let along MonoTouch. Mono's WCF stack is immature and MT implements only a subset from that... — TheNextman, Aug 05 '11 at 16:45

score 2 · Accepted Answer · answered Aug 05 '11 at 14:50

2

In all honesty, I am unfamiliar with the WCF options available to you in monmotouch; they are very different between regular .NET and Silvelight, for example - and I see no reason to assume that monotouch has the ability to swap serializer at runtime (which "full" .NET does, at least under the MS version). This makes it hard to do the transition silently, as we can't wrestle control from DataContractSerializer.

As such, IMO the simplest option is to seize control of the data manually, and send raw byte[] - ideally with MTOM encoding enabled if monotouch can do that. Then once you have your byte[] the world is your mollusc, as they say.

Re changes to your types... well, MyFunction() is an oddity, in that it doesn't transfer any data, so I'm not sure what you want me to suggest on that one. With MyClass, all it needs is a unique number (unique within the type, not globally) per member, i.e.

[DataContract]
public class MyClass
{
    [DataMember(Order=1)] // <==== this provides the 1 as the key
    public int SomeProp {get; set;}

    // see below re callback
}

You also have a serialization callback; these are fully supported, but it expects to find a familiar pattern - StreamContext is not one that I know of (although it should work with StreamingContext and a few others).

Finally, note that by default protobuf-net executes the constructor, which is different to DataContractSerializer. If you desire, you can suppress this via:

[DataContract(SkipConstructor=true)]
public class MyClass {...}

If I've missed the intent here, let me know.

Note there are also ways of doing all the configuration without changing/adding any attributes if you prefer.

answered Aug 05 '11 at 14:50

Marc Gravell

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Thank you for your answer Marc. What I meant to show in my interface (MyFunction) is that I have a ServiceContract attribute and a OperationContract. What I would want to know is does these attributes remains the same? And I made a mistake when typing my exemple, it is not a StreamContext but a StreamingContext. I'll edit my post. – Jean-Philippe Leclerc Aug 05 '11 at 15:00
And How would I do the configuration without changing any attributes? – Jean-Philippe Leclerc Aug 05 '11 at 15:08
@Jean - re the latter question; "v2" has a `RuntimeTypeModel` which allows everything to be configured. Re the first - without replacing the core serializer (which you can do in MS full .NET). Hence my suggestion to use `byte[]` as the core object on the API, so that we can control serialization *outside* this. Not as convenient as full .NET, I agree. Of course, at that point you might wonder what WCF is adding for you.... maybe a raw socket or HTTP POST is simpler. – Marc Gravell Aug 05 '11 at 21:45
@MarcGravell is there anyway to automatically fill the Order from DataContract to be used in Protobuf.NET as the Name alphabetically ordered? Eg: [DataMember(Name = "a") would be Order=1. – Iúri dos Anjos Jun 28 '18 at 22:20
@IúridosAnjos to clarify: are there Order=x on the existing data member attributes? and are they unique? but perhaps "off by one", i.e. start at zero? Or are they lacking Order=x? – Marc Gravell Jun 28 '18 at 23:16
@MarcGravell no, I'm not setting Order property. I added a new question showing my problem and all details about it. It would be better if you check it: https://stackoverflow.com/questions/51092369/protobuf-net-serialization-for-inheritance-classes – Iúri dos Anjos Jun 28 '18 at 23:26

How to properly migrate from WCF DatacontractSerializer to Protobuf-net?

1 Answers1