Message Serializers Edit on GitHub

The serialization mechanism and defaults are likely to change in Jasper. We will be deprecating the old Xml serialization and adding some basic content negotiation to enable teams to start moving individual applications to more efficient serializers. Jil? Protobuffers? To be determined.

We also want to be able to configure serialization readers per incoming message type as a way of further decoupling applications without having to share a common library of message DTO types.

To send a message, FubuMVC serializes the actual message body to a byte[] array before submitting the message through a configured channel. Upon receipt of a message, FubuMVC will deserialize the byte[] array back into the desired message body object. The deserialization is lazy and is evaluated on the first access of `Envelope as shown below:


public void ShowSerialization(Envelope envelope)
{
    // Accessing the Message property will
    // invoke the deserialization
    var message = envelope.Message;
}

How a Serializer is Chosen

When a new message is about to be sent via a remote transport, FubuMVC selects a serializer based on this progression:

If the Envelope.ContentType header is already set, choose a serializer matching that content type
If there is a default serializer for the channel a message is being sent to, use that serializer
Use the default serializer for the application

Do note that it's valid for FubuMVC to send the same message with a different serialization content type to different channels in pub/sub scenarios.

Explicitly Choose Serialization per Message

If you drop down to the lower level IEnvelopeSender service, you can explicitly choose the serializer choice for a particular message. That usage is shown below:


public void SendEnvelope(IEnvelopeSender sender)
{
    var envelope = new Envelope
    {
        Message = new PingMessage(),
        ContentType = "application/json"
    };

    sender.Send(envelope);
}

Out of the Box Serializers

FubuMVC 3.0 has only a couple out of the box serializers:

Xml serialization via a custom mechanism that was specifically used to maintain compatibility with the older Rhino Service Bus tooling
Binary serialization using .Net's built in binary formatter
JSON serialization via Newtonsoft.Json using the default JSON settings of the application

Custom Serializers

You can plug a new serializer into FubuMVC by implementing the IMessageSerializer interface as shown below:


public class MyCustomSerializer : IMessageSerializer
{
    public void Serialize(object message, Stream stream)
    {
        // write the message object to the stream
    }

    public object Deserialize(Stream message)
    {
        // deserialize the stream into the message object
        return null;
    }

    public string ContentType { get; } = "text/special";
}

See the next section for configuration options to use your custom serializer.

Configuring Serialization Defaults

Below is some samples of adding custom serializers, configuring the default serialization for the application, and establishing the default serialization for a specific channel.


public class SerializedApp : FubuTransportRegistry<AppSettings>
{
    public SerializedApp()
    {
        // Register a custom message serializer
        Services.AddService<IMessageSerializer, MyCustomSerializer>();

        // Set a default serializer for the entire application
        ServiceBus.DefaultSerializer<BinarySerializer>();

        // Set a default serializer by choosing the content
        // type of an installed serializer
        ServiceBus.DefaultContentType("application/json");

        // Set the default serializer for a single channel
        Channel(x => x.Transactions)
            .DefaultSerializer<BinarySerializer>();

        // Set the default serializer for a specific channel
        // by choosing the content type of an installed serializer
        Channel(x => x.Control)
            .DefaultContentType("application/xml");
    }
}

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