SOAP WCF WS-Addressing自定义Action头报重复头异常如何解决？

问题原因 #

WCF客户端生成的代理类在调用时会默认自动生成一个Action头，命名空间为http://schemas.microsoft.com/ws/2005/05/addressing/none，你通过OutgoingMessageHeaders.Action赋值的操作会额外新增一个同命名空间的Action头，最终导致重复冲突。

解决方案1：直接修改现有头（适配单接口修改场景） #

在赋值前先删除已存在的同命名空间Action头，再进行赋值即可，代码修改如下：

public async Task<getAttorneyResponseStructure> GetAttorneyAsync(GetAttorneyRequestStructure getAttorneyRequestStructure)
{
  try
  {
    using (new OperationContextScope(Client.InnerChannel))
    {
      getAttorneyRequestStructure.AttorneyHeader = Header;

      // To头无默认冲突可直接赋值
      OperationContext.Current.OutgoingMessageHeaders.To = new Uri("http://rydwvgsn01.spga.gov.sa/GSBExpress/Legal/MOJAttorneyInquiry/2.0/AttorneyInquiryService.svc");
      
      // 先移除已存在的默认Action头
      var defaultActionNamespace = "http://schemas.microsoft.com/ws/2005/05/addressing/none";
      OperationContext.Current.OutgoingMessageHeaders.RemoveAll("Action", defaultActionNamespace);
      
      // 赋值自定义Action
      OperationContext.Current.OutgoingMessageHeaders.Action = "http://tempuri.org/IAttorneyInquiryService/GetAttorney";
      
      // 如需自定义Action头的命名空间，替换上一行的赋值逻辑即可
      // var customActionHeader = MessageHeader.CreateHeader("Action", "你的自定义命名空间", "http://tempuri.org/IAttorneyInquiryService/GetAttorney");
      // OperationContext.Current.OutgoingMessageHeaders.Add(customActionHeader);

      return await Client.GetAttorneyAsync(getAttorneyRequestStructure);
    }
  }
  catch (Exception e)
  {
   throw;
  }
}

解决方案2：使用IClientMessageInspector全局拦截修改（适配多接口统一修改场景） #

如果项目内多个接口都需要自定义SOAP头，可通过消息拦截器统一处理，避免每个接口重复写逻辑：

1. 实现IClientMessageInspector接口处理消息修改逻辑

public class CustomSoapHeaderInspector : IClientMessageInspector
{
    public void AfterReceiveReply(ref Message reply, object correlationState)
    {
        // 响应处理逻辑按需添加即可
    }

    public object BeforeSendRequest(ref Message request, IClientChannel channel)
    {
        // 修改To头
        request.Headers.To = new Uri("http://rydwvgsn01.spga.gov.sa/GSBExpress/Legal/MOJAttorneyInquiry/2.0/AttorneyInquiryService.svc");
        
        // 移除默认Action头
        var defaultActionNs = "http://schemas.microsoft.com/ws/2005/05/addressing/none";
        request.Headers.RemoveAll("Action", defaultActionNs);
        
        // 设置自定义Action，按需调整命名空间
        request.Headers.Action = "http://tempuri.org/IAttorneyInquiryService/GetAttorney";
        return null;
    }
}

2. 实现IEndpointBehavior将拦截器注入客户端终结点

public class CustomSoapHeaderBehavior : IEndpointBehavior
{
    public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters) { }
    public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
    {
        clientRuntime.ClientMessageInspectors.Add(new CustomSoapHeaderInspector());
    }
    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher) { }
    public void Validate(ServiceEndpoint endpoint) { }
}

3. 客户端初始化时添加该行为即可全局生效

Client.Endpoint.EndpointBehaviors.Add(new CustomSoapHeaderBehavior());

内容的提问来源于stack exchange，提问作者Nasser X