Is removing a MessageBodyMember in a MessageContract considered a breaking change?

Question

Consider the following ServiceContract-Interface:

[ServiceContract]
public interface ITest
{
    [OperationContract]
    void MyMethod(MyClass obj);
}

With MyClass beeing:

[MessageContract]
public MyClass
{
    [MessageBodyMember(Order = 0)]
    public int A { get; set; }

    [MessageBodyMember(Order = 1)]
    public int B { get; set; }

    [MessageBodyMember(Order = 2)]
    public int C { get; set; }
}

MyClass is now changed to look like the following:

[MessageContract]
public MyClass
{
    [MessageBodyMember(Order = 0)]
    public int A { get; set; }

    [MessageBodyMember(Order = 2)]
    public int C { get; set; }
}

Would a client consuming this WCF-Service need to make additional changes to work with the new service definition?

Additionaly, what would happen if I were to additionally change C to have the new Order = 1?

naro · Accepted Answer · 2015-09-01T06:51:16.450

2

If the client updates the WSDL File, it gets a syntax error in the code of the client, when the client calls the method.

The order element set on which position in the communication the bodymember sending to the server/client. You can see it into the svc log. Example.:

<ns2: myClass xmlns:ns2="yourNamespace">
<A xmlns=""></A>
<B xmlns=""></B>
<C xmlns=""></C>
</ns2:myClass>

After changed the ordner element:

<ns2: myClass xmlns:ns2="yourNamespace">
<C xmlns=""></C>
<A xmlns=""></A>
<B xmlns=""></B>
</ns2: myClass >

I have tried the example for you. I have used a WCF C# Web service and a C# client with a standard protocol: BasicHttpBinding. And I use the WCF Test client. In this combination I got no error in the client, provided that the client makes no WSDL update. In this case, you can change the order element without errors. But this is not a correct implementation; therefore you can’t assume that everything is working. For other clients see the result might be different. For example, a Java client is much more restrictive.

edited Sep 01 '15 at 06:51

answered Aug 31 '15 at 13:15

naro

416
7
16

Thank you! Since the Class is only used to send data from client to server I take it that with your explanation the client can still use the service even if no wsdl update was made? – Shion Aug 31 '15 at 13:36
If you send data from client to server, with the object “MyClient”, you have to fill the Object into the client. Isn’t the client set the MessageBodyMember “B”? – naro Aug 31 '15 at 14:19
Of course the client will still fill "B" and pass it to the server, the client hasn't updated the wsdl. The question is: Will the server be able to handle this and take on the request? – Shion Aug 31 '15 at 14:26
What happend when you have an object inside an object? Can you use the Order attribute for other the inside properties? – Luis.Andrade Oct 14 '16 at 17:33

score 0 · Answer 2 · answered Sep 07 '15 at 09:07

Adding to @naro's answer:

It is not a breaking change for the following frameworks:

.NET (C#, 4.5)
Java 8

I did not test anything else as it doesn't matter for our scenario.

This means every client still works (without regenerating the client) even after updating the web service definition.

Is removing a MessageBodyMember in a MessageContract considered a breaking change?

2 Answers2