Object graph serialization in .NET and code version upgrades

Question

I need to serialize some object graphs to disc

What difficulties am I likely to encounter if I make changes to a class, then try to deserialize an old version?

Do some serializers handle this better than others?

What is the standard way of handling such a scenario?

For example, in a new version of the code, do I need to retain all the old classes so that when deserializing an old file i can do so to the old class, then migrate the data to the new class? Will changing the class' name/namespace break deserialization?

Thanks for any advice

Answer 1

Well, as I remember, the problems starts after:

• Adding a new field/property to a class;
• Changing the type of an existing field/property.

You can have custom serialization to handle versioning problems on you own.

But I would recommend to use DataContractSerializer along with Best Practices: Data Contract Versioning for the most common cases.

Answer 2

This kind of depends upon what format you need the serialised data in. If you use .NET 1.0 binary serialisation, then you'll be limited to a specific version of the DLL. I wouldn't recommend that.

Personally I'd suggest using DataContracts with the default WCF serialiser: DataContractSerialiser. You can control what happens when you deserialise a different version of the type with techniques like [OnDeserializing] and IExtensibleDataObject.

You can have DataContractSerializer output XML or binary too.