Controlling serialization in Web API / APIController

Question

Where can I specify custom serialization/deserialization in an ASP.NET Web API?

The throughput of our application requires a fast serialization/deserialization of messages, hence we need to tightly control this part of the code to either use our home-brew or an OSS one out there.

I have checked various sources such as this that explains how to create a custom value provider, but I have yet to see an example that explains the process end to end.

Can anyone direct/show me the way to serialize the incoming/outgoing messages?

Also a diagram of the various injection points/event sinks in Web API similar to this one for WCF is appreciated!

Answer 1

The extension point you're looking for is the MediaTypeFormatter. It controls reading from the request body and writing to the response body. This might be the best resource for writing your own formatter:

http://www.asp.net/web-api/overview/formats-and-model-binding/media-formatters

Answer 2

Here's code example in case link in the answer above dies

public class MerlinStringMediaTypeFormatter : MediaTypeFormatter
{
    public MerlinStringMediaTypeFormatter()
    {
        SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/plain"));
    }

    public override bool CanReadType(Type type)
    {
        return type == typeof (YourObject); //can it deserialize
    }

    public override bool CanWriteType(Type type)
    {
        return type == typeof (YourObject); //can it serialize
    }

    public override Task<object> ReadFromStreamAsync( 
        Type type, 
        Stream readStream, 
        HttpContent content, 
        IFormatterLogger formatterLogger)
    {
        //Here you put deserialization mechanism
        return Task<object>.Factory.StartNew(() => content.ReadAsStringAsync().Result);
    }

    public override Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, TransportContext transportContext)
    {
        //Here you would put serialization mechanism
        return base.WriteToStreamAsync(type, value, writeStream, content, transportContext);
    }
}

Then you need to register your formatter in Global.asax

protected void Application_Start()
    {
        config.Formatters.Add(new MerlinStringMediaTypeFormatter());
    }

Hope this saves you some time.