以编程方式从 WCF Web HTTP 服务帮助页面中删除方法？

Question

如何以编程方式从WCF Web HTTP Service Help Page 中删除服务方法？我仍然希望显示帮助页面，但我需要从中删除特定方法——而不更改 ServiceContract。

我尝试通过自定义 IEndpointBehavior 从 ServiceEndpoints 中删除服务方法，如下所示：

    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
    {
        var operationsToRemove = endpointDispatcher.DispatchRuntime.Operations.Where(op => this.IsDeprecated(op)).ToList();
        foreach (var operation in operationsToRemove)
        {
            endpointDispatcher.DispatchRuntime.Operations.Remove(operation);
        }
    }

...当调用不推荐使用的方法时，我收到“方法不允许”错误（根据需要）。

我还尝试按照this article 中的步骤从 WSDL/自动生成的客户端中省略服务方法，但这似乎不会影响帮助页面。

Answer 1

您可以以编程方式进行，但我相信这样做的方式不适合生产环境。微软在 System.ServiceModel.Web.dll 中隐藏的 HelpPage 的实现，并且没有可扩展点来更改此行为。

但是我们知道当前的实现，我们可以使用反射来实现 HelpPage 方法的动态管理。但是 MS 可以更改合同和实施细节，我们的实施将被破坏。所以，我强烈不建议在真实环境中使用它。

这是一个自定义的 BadCustomHelpPageWebHttpBehavior（继承自 WebHttpBehavior）。构造函数采用一系列方法从帮助页面中排除：

public class BadCustomHelpPageWebHttpBehavior : WebHttpBehavior
{
    /// <summary>
    /// Creates BadCustomHelpPageWebHttpBehavior
    /// </summary>
    /// <param name="ignoredMethodNames">Array of method names to ignore in Help Page</param>
    public BadCustomHelpPageWebHttpBehavior(string[] ignoredMethodNames)
    {
        m_ignoredMethodNames = ignoredMethodNames;
    }

    /// <summary>
    /// Remove methods to display in Help Page by names passed in the constructor
    /// </summary>
    public override void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
    {
        base.ApplyDispatchBehavior(endpoint, endpointDispatcher);

        if (m_ignoredMethodNames == null || m_ignoredMethodNames.Length == 0)
            return;

        DispatchOperation helpOperation = endpointDispatcher.DispatchRuntime.Operations.FirstOrDefault(o => o.Name == "HelpPageInvoke");
        if(helpOperation == null)
            return;

        IOperationInvoker helpInvoker = helpOperation.Invoker;

        Type helpInvokerType = CreateInternalSystemServiceWebType("System.ServiceModel.Web.HelpOperationInvoker");
        FieldInfo helpPageFieldInfo = helpInvokerType.GetField("helpPage",
            BindingFlags.Instance | BindingFlags.NonPublic);
        if (helpPageFieldInfo != null)
        {
            object helpPage = helpPageFieldInfo.GetValue(helpInvoker);

            Type helpPageType = CreateInternalSystemServiceWebType("System.ServiceModel.Dispatcher.HelpPage");
            Type operationHelpInformationType =
                CreateInternalSystemServiceWebType("System.ServiceModel.Dispatcher.OperationHelpInformation");

            Type dictionaryType = typeof (Dictionary<,>);
            Type[] operationInfoDictionaryGenericTypes = {typeof (string), operationHelpInformationType};
            Type operationInfoDictionaryType = dictionaryType.MakeGenericType(operationInfoDictionaryGenericTypes);

            FieldInfo operationInfoDictionaryFieldInfo = helpPageType.GetField("operationInfoDictionary",
                BindingFlags.Instance | BindingFlags.NonPublic);
            if (operationInfoDictionaryFieldInfo != null)
            {
                object operationInfoDictionary = operationInfoDictionaryFieldInfo.GetValue(helpPage);
                object operationInfoDictionaryReplaced = RemoveHelpMethods(operationInfoDictionary,
                    operationInfoDictionaryType);
                operationInfoDictionaryFieldInfo.SetValue(helpPage, operationInfoDictionaryReplaced);
            }
        }
    }

    private object RemoveHelpMethods(object operationInfoDictionary, Type operationInfoDictionaryType)
    {
        Debug.Assert(m_ignoredMethodNames != null);

        var operationInfoDictionaryReplaced = Activator.CreateInstance(operationInfoDictionaryType);

        var operationInfoDictionaryAsEnumerable = operationInfoDictionary as IEnumerable;
        if (operationInfoDictionaryAsEnumerable != null)
        {
            foreach (var operationInfoEntry in operationInfoDictionaryAsEnumerable)
            {
                object key = operationInfoEntry.GetType().GetProperty("Key").GetValue(operationInfoEntry);
                object value = operationInfoEntry.GetType().GetProperty("Value").GetValue(operationInfoEntry);

                string name = value.GetType().GetProperty("Name").GetValue(value) as string;

                if (m_ignoredMethodNames.Contains(name) == false)
                {
                    operationInfoDictionaryReplaced.GetType()
                        .GetMethod("Add")
                        .Invoke(operationInfoDictionaryReplaced, new[] {key, value});
                }
            }
        }

        return operationInfoDictionaryReplaced;
    }

    private static Type CreateInternalSystemServiceWebType(string requestedType)
    {
        return typeof (WebServiceHost).Assembly.GetType(requestedType);
    }

    private readonly string[] m_ignoredMethodNames;
}

要使用此类，只需将此行为添加到您的端点：

host.Description.Endpoints[0].Behaviors.Add(new BadCustomHelpPageWebHttpBehavior(new[] { "EchoWithGet" })
{
    HelpEnabled = true
});

可以在此处找到此示例的完整源代码，包括简单的 WCF HTTP 服务器： https://github.com/knyu15/BadCustomHelpPageWebHttpBehavior

可能更好的方法是将 WCF HelpPage 替换为您的自定义页面。详细示例可以在这里找到： Customize the WebHttp Help Output in WCF。但这并不能回答您的直接问题。