Wcf – Why is WCF so important and in what cases is it used

Actually, although I blogged (see Luke's answer), I think this is better than my IDisposable wrapper. Typical code:

Service<IOrderService>.Use(orderService=>
{
  orderService.PlaceOrder(request);
}); 

(edit per comments)

Since Use returns void, the easiest way to handle return values is via a captured variable:

int newOrderId = 0; // need a value for definite assignment
Service<IOrderService>.Use(orderService=>
  {
    newOrderId = orderService.PlaceOrder(request);
  });
Console.WriteLine(newOrderId); // should be updated

The advantage to this is that it is applied to every call.

Create a class that implements IClientMessageInspector. In the BeforeSendRequest method, add your custom header to the outgoing message. It might look something like this:

public object BeforeSendRequest(ref System.ServiceModel.Channels.Message request, System.ServiceModel.IClientChannel channel)
{
    HttpRequestMessageProperty httpRequestMessage;
    object httpRequestMessageObject;
    if (request.Properties.TryGetValue(HttpRequestMessageProperty.Name, out httpRequestMessageObject))
    {
        httpRequestMessage = httpRequestMessageObject as HttpRequestMessageProperty;
        if (string.IsNullOrEmpty(httpRequestMessage.Headers[USER_AGENT_HTTP_HEADER]))
        {
            httpRequestMessage.Headers[USER_AGENT_HTTP_HEADER] = this.m_userAgent;
        }
    }
    else
    {
        httpRequestMessage = new HttpRequestMessageProperty();
        httpRequestMessage.Headers.Add(USER_AGENT_HTTP_HEADER, this.m_userAgent);
        request.Properties.Add(HttpRequestMessageProperty.Name, httpRequestMessage);
    }
    return null;
}

Then create an endpoint behavior that applies the message inspector to the client runtime. You can apply the behavior via an attribute or via configuration using a behavior extension element.

Here is a great example of how to add an HTTP user-agent header to all request messages. I am using this in a few of my clients. You can also do the same on the service side by implementing the IDispatchMessageInspector.

Is this what you had in mind?

Update: I found this list of WCF features that are supported by the compact framework. I believe message inspectors classified as 'Channel Extensibility' which, according to this post, are supported by the compact framework.