title: Set response format html Message in WCF C#
body: <p>There is a WCF-service in C#:</p>
  
  <pre><code>[ServiceBehavior(AddressFilterMode = AddressFilterMode.Any, InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Single, IncludeExceptionDetailInFaults = true)]
  [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
  class SubscriptionService : ISubscriptionService
  {        
      public Message Help(Message m)
      {
          WebOperationContext.Current.OutgoingResponse.ContentType = "text/html; charset=utf-8";
          return new WebHttpHelpPageMessage();
      }
  }
  
  [ServiceContract]
  interface ISubscriptionService
  {        
      [OperationContract]
      [WebInvoke(UriTemplate = "*", Method = "*")]
      Message Help(Message m);
  }
  </code></pre>
  
  <p>Message from the inherited class:</p>
  
  <pre><code>public class WebHttpHelpPageMessage : Message
  {
      ...
  
      protected override void OnWriteBodyContents(System.Xml.XmlDictionaryWriter writer)
      {
          writer.WriteStartElement("html");
          writer.WriteRaw("&lt;head&gt;&lt;/head&gt;&lt;body&gt;&lt;p&gt;Hi&lt;/p&gt;&lt;/body&gt;");
          writer.WriteEndElement();
      }
  }
  </code></pre>
  
  <p>The result in the browser - XML, how to do it to be HTML?</p>