Question: By defining an attribute that implements IContactBehavior and IWsdlExportExtension and set that attribute on your service contract, you can easily add **Soap Headers to your wsdl** (see <http://wcfextras.codeplex.com/> for more information)

But now I need to set a Soap Header contract in the wsdl on all Operationcontracts and this time I cannot set an attribute.

Following code (called from IWsdlExportExtension.ExportEndPoint) doesn't work, but does work when called from the SoapHeaderAttributes (that executes an IWsdlExportExtension.ExportContract)

```
foreach (OperationDescription operationDescription in context.ContractConversionContext.Contract.Operations)
{
   AddSoapHeader(operationDescription, "SomeHeaderObject", typeof(SomeHeaderObject), SoapHeaderDirection.InOut);                    
}

internal static void AddSoapHeader(OperationDescription operationDescription, string name, Type type, SoapHeaderDirection direction)
{
    MessageHeaderDescription header = GetMessageHeader(name, type);
    bool input = ((direction & SoapHeaderDirection.In) == SoapHeaderDirection.In);
    bool output = ((direction & SoapHeaderDirection.Out) == SoapHeaderDirection.Out);

    foreach (MessageDescription msgDescription in operationDescription.Messages)
    {
        if ((msgDescription.Direction == MessageDirection.Input && input) ||
            (msgDescription.Direction == MessageDirection.Output && output))
            msgDescription.Headers.Add(header);
    }
}

internal static MessageHeaderDescription GetMessageHeader(string name, Type type)
{
    string headerNamespace = SoapHeaderHelper.GetNamespace(type);
    MessageHeaderDescription messageHeaderDescription = new MessageHeaderDescription(name, headerNamespace);
    messageHeaderDescription.Type = type;
    return messageHeaderDescription;
}

```

Anyone has an idea how to apply this code on all operations (without using attributes) and by doing this, adding the contract of the header to the wsdl ?

Answer: 
The IEndpointBehavior has the following interface:

```
ApplyDispatchBehavior(ServiceEndpoint endPoint, EndPointDispatcher endpointDispatcher);

```

You can add Soap Headers to the wsdl for operations by iterating over the endpoint.Contract.Operations in the ApplyDispatchBehavior.

Here you have the complete solution that worked for me:

```
void IEndpointBehavior.ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
{
    foreach (OperationDescription operationDescription in endpoint.Contract.Operations)
    {
        foreach (MessageDescription msgDescription in operationDescription.Messages)
        {
            AddSoapHeader(operationDescription, "SomeHeaderObject", typeof(SomeHeaderObject), SoapHeaderDirection.InOut);
        }
    }
}

internal static void AddSoapHeader(OperationDescription operationDescription, string name, Type type, SoapHeaderDirection direction)
{
    MessageHeaderDescription header = GetMessageHeader(name, type);
    bool input = ((direction & SoapHeaderDirection.In) == SoapHeaderDirection.In);
    bool output = ((direction & SoapHeaderDirection.Out) == SoapHeaderDirection.Out);

    foreach (MessageDescription msgDescription in operationDescription.Messages)
    {
            if ((msgDescription.Direction == MessageDirection.Input && input) ||
                    (msgDescription.Direction == MessageDirection.Output && output))
                    msgDescription.Headers.Add(header);
    }
}

internal static MessageHeaderDescription GetMessageHeader(string name, Type type)
{
    string headerNamespace = SoapHeaderHelper.GetNamespace(type);
    MessageHeaderDescription messageHeaderDescription = new MessageHeaderDescription(name, headerNamespace);
    messageHeaderDescription.Type = type;
    return messageHeaderDescription;
}

```

The SoapHeaderHelper can be found in the [WcfExtras](http://wcfextras.codeplex.com/).
You might want to have a look at the [WCFExtras](http://www.codeplex.com/WCFExtras) project on CodePlex - it has some support for custom SOAP headers and stuff like that. Not 100% sure if it's capable of filling your need, but check it out!

Marc

UPDATE: have you looked into creating a WCF extension, e.g. something like a message inspector, on both the client and the server side? 

The client side IClientMessageInspector defines two methods `BeforeSendRequest` and `AfterReceiveReply` while the server side IDispatchMessageInspector has the opposite methods, i.e. `AfterReceiveRequest` and `BeforeSendReply`.

With this, you could add headers to every message going across the wire (or selectively only to a few).

Here's a snippet from a IClientMessageInspector implementor we use to automagically transmit the locale information (language and culture info) across from the clients to the server - should give you an idea how to get started:

```
public object BeforeSendRequest(ref Message request, IClientChannel channel)
{
    International intlHeader = new International();
    intlHeader.Locale = CultureInfo.CurrentUICulture.TwoLetterISOLanguageName;

    MessageHeader header = MessageHeader.CreateHeader(WSI18N.ElementNames.International, WSI18N.NamespaceURI, intlHeader);
    request.Headers.Add(header);

    return null;
}

```