Xamarin.Android 中实际实现了 .NETStandard 的哪些 API？

Question

如何确定 .NETStandard API 是否实际上是 Xamarin.Android 的 implemented/supported？我有一个在 .NETStandard1.4 库中实现的 WCF net.tcp 客户端。我从 Xamarin.Android 应用程序引用此库并尝试调用客户端方法。它编译正常，但在客户端方法调用时抛出 NotImplementedException。

那么 Xamarin.Android 是否可以不实现一些 API 但仍然 "supports" .NETStandard1.4？我问是因为我找不到任何说它不受支持的东西，我想使用的所有 classes/methods 都记录在 Xamarins 在线文档中（例如 https://developer.xamarin.com/api/type/System.ServiceModel.ClientBase%3CTChannel%3E/），没有提到 "Not Implemented" ，但我得到 NotImplementedException。目前我不知道它是否真的不受支持，或者我的 installation/project.

是否有问题

如果是，那么 .NETStandard 库的确切目的是什么，是否有人可以声称支持它并抛出 NotImplementedException 一切？

完整性：

Xamarin.Android 应用程序：

// MainActivity.cs
using Android.App;
using Android.Widget;
using Android.OS;
using System.ServiceModel;

namespace App1
{
    [Activity(Label = "App1", MainLauncher = true, Icon = "@drawable/icon")]
    public class MainActivity : Activity
    {
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Set our view from the "main" layout resource
            // SetContentView (Resource.Layout.Main);
            var endpoint = new EndpointAddress("net.tcp://192.168.192.189:8550/iQOSApp_AppService");
            var binding = new NetTcpBinding(SecurityMode.None);
            var client = new iQOSApp.Clients.AppContractClient(binding, endpoint);
            int n = client.GetData(0); // NotImplementedException
        }
    }
}

.NET 标准库：

// Clients.cs
//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//     Runtime Version:4.0.30319.42000
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

namespace iQOSApp.Clients
{


    [System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "4.0.0.0")]
    [System.ServiceModel.ServiceContractAttribute(ConfigurationName = "iQOSApp.Clients.IAppContract")]
    public interface IAppContract
    {

        [System.ServiceModel.OperationContractAttribute(Action = "http://tempuri.org/IAppContract/GetData", ReplyAction = "http://tempuri.org/IAppContract/GetDataResponse")]
        int GetData(int value);

        [System.ServiceModel.OperationContractAttribute(Action = "http://tempuri.org/IAppContract/GetData", ReplyAction = "http://tempuri.org/IAppContract/GetDataResponse")]
        System.Threading.Tasks.Task<int> GetDataAsync(int value);
    }

    [System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "4.0.0.0")]
    public interface IAppContractChannel : iQOSApp.Clients.IAppContract, System.ServiceModel.IClientChannel
    {
    }

    [System.Diagnostics.DebuggerStepThroughAttribute()]
    [System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "4.0.0.0")]
    public partial class AppContractClient : System.ServiceModel.ClientBase<iQOSApp.Clients.IAppContract>, iQOSApp.Clients.IAppContract
    {

        public AppContractClient()
        {
        }

        public AppContractClient(string endpointConfigurationName) :
                base(endpointConfigurationName)
        {
        }

        public AppContractClient(string endpointConfigurationName, string remoteAddress) :
                base(endpointConfigurationName, remoteAddress)
        {
        }

        public AppContractClient(string endpointConfigurationName, System.ServiceModel.EndpointAddress remoteAddress) :
                base(endpointConfigurationName, remoteAddress)
        {
        }

        public AppContractClient(System.ServiceModel.Channels.Binding binding, System.ServiceModel.EndpointAddress remoteAddress) :
                base(binding, remoteAddress)
        {
        }

        public int GetData(int value)
        {
            return base.Channel.GetData(value);
        }

        public System.Threading.Tasks.Task<int> GetDataAsync(int value)
        {
            return base.Channel.GetDataAsync(value);
        }
    }
}

Answer 1

So can it be, that Xamarin.Android doesn't implement some APIs but still "supports" .NETStandard1.4?

是的，没错。事实上，有许多旧平台会在它们没有实现的区域抛出 NIE（未实现的异常）。这更像是一个单声道兼容性的东西：http://www.mono-project.com/docs/about-mono/compatibility/

您可以实现自己的平台并在您的所有实现中投入 PlatformNotSupportedException，它会被视为 "Supporting netstandard"。 Aaron Nurse 对此有很好的见解：https://gist.github.com/davidfowl/8939f305567e1755412d6dc0b8baf1b7#gistcomment-1759645

因此，您很可能运行遇到了缺少某些功能的 Mono 的 WCF 堆栈问题：

http://www.mono-project.com/docs/web/wcf/

In general, the Xamarin platform supports the same client-side subset of WCF that ships with the Silverlight runtime. This includes the most common encoding and protocol implementations of WCF — text-encoded SOAP messages over the HTTP transport protocol using the BasicHttpBinding class. In addition, WCF support requires the use of tools only available in a Windows environment to generate the proxy.

https://developer.xamarin.com/guides/xamarin-forms/web-services/consuming/wcf/

注意： 请注意其中某些类型的 Xamarin 文档。它们是直接从 MSDN 中提取的，并不意味着 BCL 中列出的所有内容都受支持。更准确的汇编列表请见：

https://developer.xamarin.com/guides/cross-platform/advanced/available-assemblies/

您最好查看 Silverlight MSDN 文档：https://msdn.microsoft.com/en-us/library/system.servicemodel(v=vs.95).aspx

Xamarin.Android 中实际实现了 .NETStandard 的哪些 API？

What APIs of the .NETStandard are actually implemented in Xamarin.Android?

c#

wcf

xamarin

xamarin.android

.net-standard