Custom WCF DataContractSerializer

Is it possible to replace dataContractSerializer in Windows Communication Foundation with my own serializer. If it is possible, how can I achieve this?

Yes, you can provide your own serializer implementation. By default WCF will use the DataContractSerializer. To provide your own serializer you must write your own IOperationBehavior which seeks out and removes the currently applied DataContractSerializerOperationBehavior from the OperationDescription::Behaviors collection and then applies a custom instance of an DataContractSerializerOperationBehavior. The DataContractSerializerOperationBehavior is then responsible for constructing an XmlObjectSerializer implementation in it's CreateSerializer factory methods. For some code samples for how to do this, check out this article by Dan Rigsby.

From there, it's all about implementing your own custom XmlObjectSerializer which will allow you to serialize the XML infoset to any representation you want.

The WCF team did this when they introduced DataContractJsonSerializer.

There are far more touchpoints than the ones mentioned here in the other two answers -- for example you may have to introduce and change the operation behaviors and operation formatters being used, add a new encoder, and add entirely new service and client behaviors as well. It depends on what the new serialization format is and what you're trying to do.

However, if your goal is to only add a new serializer for stand-alone serialization, it's simpler.

What I would recommend is -- look at all the different usage of DataContractJsonSerializer (via Reflector) in System.Runtime.Serialization.dll, System.ServiceModel.Web.dll, and System.Runtime.ServiceModel.dll.

If you're interested in only the standalone serialization aspect, just look at the DataContractJsonSerializer and the associated classes in the Serialization namespace. It should be fairly intuitive for you to grasp the various subtleties of custom serialization implementation. Ask away if you have specific questions, but I truly believe this is the quickest and most elegant way to learn this particular solution...

Normally you place the attribute [DatacontractSerializer] or [XmlSerializer] above the Service Contract, im pretty sure you could create your own hence why you apply them as attributes, now if only reflector would start so that i could inspect the XmlSerializer and find out what makes it tick.

msdn insist that classes that want to be serialized via the XmlSerializer, must be decorated with [XmlAttribute] or [XmlElement] attributes (since it would give more shape to the xml file understandingly), but it does work if your classes are decorated with the [DataMember], which is compatible with DataContractSerializer, hence why you should be able to create your own serializer that will serialize anything with a [DataMember] tag, just like the XmlSerializer