WCF response leaving out <xml header> - wcf

Question

I am finally starting to get somewhere with WCF, but I have run into another problem. The response sent back does not include the header
<?xml version="1.0" encoding="utf-8" ?>
My Service Contract
[ServiceContract]
public interface IService1
{
// you can have optional parameters by simply specifying them and they will return null if there is nothing in there
[WebGet(UriTemplate="testing={value}", ResponseFormat = WebMessageFormat.Xml)]
[OperationContract]
XElement GetData(string value);
}
[XmlSerializerFormat]
public class Service1 : IService1
{
public XElement GetData(string value)
{
return new XElement("Somename", value);
}
}
returns this (3 is the value specified)
<Somename>3</Somename>
Is it also possible to easily wrap a response in a root element? Something like <response></response>?

Answer 1

responsThe result of calling the GetData method is the contents of what you return in the method. If you want a wrapper then return something like:
[XmlSerializerFormat]
public class Service1 : IService1
{
public XElement GetData(string value)
{
return new XElement("response",
new XElement("Somename", value));
}
}
EDIT:
To add the XML declaration (which actually may not be a good idea but you know best) do something like this:
var doc = new XDocument(
new XElement("response",
new XElement("Somename", value)));
doc.Declaration = new XDeclaration("1.0", "utf-8", "true");
return doc.Root;

Answer 2

I was looking for an answer to this myself, and stumbled upon this article:
http://shevaspace.blogspot.com/2009/01/include-xml-declaration-in-wcf-restful.html
It solved the problem in my situation, perhaps it is of help for others as well. It describes a custom attribute IncludeXmlDeclaration that you can stick on your method, and it will output the xml header.
For completeness, here is the code copied from the article:
public class XmlDeclarationMessage : Message
{
private Message message;
public XmlDeclarationMessage(Message message)
{
this.message = message;
}
public override MessageHeaders Headers
{
get { return message.Headers; }
}
protected override void OnWriteBodyContents(System.Xml.XmlDictionaryWriter writer)
{
// WCF XML serialization doesn't support emitting XML DOCTYPE, you need to roll up your own here.
writer.WriteStartDocument();
message.WriteBodyContents(writer);
}
public override MessageProperties Properties
{
get { return message.Properties; }
}
public override MessageVersion Version
{
get { return message.Version; }
}
}
public class XmlDeclarationMessageFormatter : IDispatchMessageFormatter
{
private IDispatchMessageFormatter formatter;
public XmlDeclarationMessageFormatter(IDispatchMessageFormatter formatter)
{
this.formatter = formatter;
}
public void DeserializeRequest(Message message, object[] parameters)
{
formatter.DeserializeRequest(message, parameters);
}
public Message SerializeReply(MessageVersion messageVersion, Object[] parameters, Object result)
{
var message = formatter.SerializeReply(messageVersion, parameters, result);
return new XmlDeclarationMessage(message);
}
}
public class IncludeXmlDeclarationAttribute : Attribute, IOperationBehavior
{
public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters)
{
}
public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation)
{
}
public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation)
{
dispatchOperation.Formatter = new XmlDeclarationMessageFormatter(dispatchOperation.Formatter);
}
public void Validate(OperationDescription operationDescription)
{
}
}