DataContractSerializer.MaxItemsInObjectGraph属性的含义

Question

One of methods of our WCF service throws exception on production environment:

The formatter threw an exception while trying to deserialize the message: There was an
error while trying to deserialize parameter http: //our_schema:GetSomeListResult. The InnerException message was 'Maximum number of items that can be serialized or deserialized in an object graph is '65536'. Change the object graph or increase the MaxItemsInObjectGraph quota.

The method GetSomeList returns a list of objects (15 properties - ints, enums, strings, DateTimes) and it has about 6k elements. However, the same service configuration doesn't lead to this error on my local machine and on test environment. I know how to fix this error:

    <behavior name="basicEndpointBehavior">
    <dataContractSerializer maxItemsInObjectGraph="2147483647"/>
    </behavior>

but I don't understand it's nature.

So what is the real number of objects in serialized/deserialized array? List.Count? List.Count*(number of properties)? If the formula is List.Count*(number of properties), number of objects = 6k*15=90k, which is greater than 65536. Why does this method call work fine locally with the same size of array?

Answer 1

It's the number of objects - ie the number of instances of things that need to get serialized. If all properties of objects in the list returns just a primitive object, then the number should be List.Count * (number of properties + 1) (each item in the list is an object, and each property of an item is another one).

The number could be significantly lower if you've set EmitDefaultValue to false , but odds are you're not doing this.

As to why the behaviour might be different locally vs. production, I've seen situations where the serializer config only applies to HTTP, and you have to set it separately for HTTPS; could this be the problem?