Dealing with Circular References in WCF

You can become a serverless blackbelt. Enrol to my 4-week online workshop Production-Ready Serverless and gain hands-on experience building something from scratch using serverless technologies. At the end of the workshop, you should have a broader view of the challenges you will face as your serverless architecture matures and expands. You should also have a firm grasp on when serverless is a good fit for your system as well as common pitfalls you need to avoid. Sign up now and get 15% discount with the code yanprs15!

Using entity classes in your application and WCF is complaining about the circular references between your classes? Well, I had the exact same problem not long ago, and I found this post on James Kovac’s blog about circular references and how to get around them:

http://www.jameskovacs.com/blog/GoingAroundInCirclesWithWCF.aspx

The key things to note from this post is that:

  1. WCF can handle circular references, but is not switched on by default
  2. There is a boolean flag in the constructor for the DataContractSerializer class which enables object references to be preserved
  3. We can tell WCF to switch this on by deriving from the DataContractSerializerOperationBehaviour class (as shown in the blog post above)

By this point you’re probably wondering why circular reference handling is not enabled by default, according to James Kovac, it’s because WCF by default tries to respect interoperability safety:

Now why can’t WCF handle circular references out-of-the-box. The reason is that there is no industry-accepted, interoperable way of expressing anything but parent-child relationships in XML. You can use the ID/IDREF feature of XML or the key/keyref feature of XML Schema, but a lot of serializers don’t respect these attributes or handle them properly. So if you want to serialize circular references, you need to stray out of the realm of safe interoperability.

So here are the classes you need to create to extend DataContractSerializerOperationBehaviour in order to preserve object reference:

public class PreserveReferencesOperationBehavior : DataContractSerializerOperationBehavior
{
     public PreserveReferencesOperationBehavior(OperationDescription operation) : base(operation)
     {
     }

     public PreserveReferencesOperationBehavior(
          OperationDescription operation, DataContractFormatAttribute dataContractFormatAttribute)
          : base(operation, dataContractFormatAttribute)
     {
     }

     public override XmlObjectSerializer CreateSerializer(
          Type type, XmlDictionaryString name, XmlDictionaryString ns, IList<Type> knownTypes)
     {
          return new DataContractSerializer(type, name, ns, knownTypes,
                                            0x7FFF /*maxItemsInObjectGraph*/,
                                            false/*ignoreExtensionDataObject*/,
                                            true/*preserveObjectReferences*/,
                                            null/*dataContractSurrogate*/);
     }
}

And the attribute to use on your operation contract:

public class PreserveReferencesAttribute : Attribute, IOperationBehavior
{
     public void AddBindingParameters(OperationDescription description,
                                      BindingParameterCollection parameters)
     {
     }

     public void ApplyClientBehavior(OperationDescription description, ClientOperation proxy)
     {
          IOperationBehavior innerBehavior = new PreserveReferencesOperationBehavior(description);
          innerBehavior.ApplyClientBehavior(description, proxy);
     }

     public void ApplyDispatchBehavior(OperationDescription description,
                                       DispatchOperation dispatch)
     {
          IOperationBehavior innerBehavior = new PreserveReferencesOperationBehavior(description);
          innerBehavior.ApplyDispatchBehavior(description, dispatch);
     }

     public void Validate(OperationDescription description)
     {
     }
}

which you apply like this:

[OperationContract]
[PreserveReferences]
MyClass RetrieveMyClass();
Liked this article? Support me on Patreon and get direct help from me via a private Slack channel or 1-2-1 mentoring.
Subscribe to my newsletter


Hi, I’m Yan. I’m an AWS Serverless Hero and I help companies go faster for less by adopting serverless technologies successfully.

Are you struggling with serverless or need guidance on best practices? Do you want someone to review your architecture and help you avoid costly mistakes down the line? Whatever the case, I’m here to help.

Hire me.


Skill up your serverless game with this hands-on workshop.

My 4-week Production-Ready Serverless online workshop is back!

This course takes you through building a production-ready serverless web application from testing, deployment, security, all the way through to observability. The motivation for this course is to give you hands-on experience building something with serverless technologies while giving you a broader view of the challenges you will face as the architecture matures and expands.

We will start at the basics and give you a firm introduction to Lambda and all the relevant concepts and service features (including the latest announcements in 2020). And then gradually ramping up and cover a wide array of topics such as API security, testing strategies, CI/CD, secret management, and operational best practices for monitoring and troubleshooting.

If you enrol now you can also get 15% OFF with the promo code “yanprs15”.

Enrol now and SAVE 15%.


Check out my new podcast Real-World Serverless where I talk with engineers who are building amazing things with serverless technologies and discuss the real-world use cases and challenges they face. If you’re interested in what people are actually doing with serverless and what it’s really like to be working with serverless day-to-day, then this is the podcast for you.


Check out my new course, Learn you some Lambda best practice for great good! In this course, you will learn best practices for working with AWS Lambda in terms of performance, cost, security, scalability, resilience and observability. We will also cover latest features from re:Invent 2019 such as Provisioned Concurrency and Lambda Destinations. Enrol now and start learning!


Check out my video course, Complete Guide to AWS Step Functions. In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. There is something for everyone from beginners to more advanced users looking for design patterns and best practices. Enrol now and start learning!