ASP.NET Core中间件(Middleware)实现WCF SOAP服务端解析

ASP.NET Core中间件(Middleware)进阶学习实现SOAP 解析。本篇将介绍实现ASP.NET Core SOAP服务端解析，而不是ASP.NET Core整个WCF host。因为WCF中不仅仅只是有SOAP， 它还包含很多如消息安全性，生成WSDL，双工信道，非HTTP传输等。ASP.NET Core 官方推荐大家使用RESTful Web API的解决方案提供网络服务。SOAP 即 Simple Object AccessProtocol 也就是简单对象访问协议。SOAP 呢，其指导理念是“唯一一个没有发明任何新技术的技术”，是一种用于访问 Web 服务的协议。因为 SOAP 基于XML 和 HTTP ，其通过XML 来实现消息描述，然后再通过 HTTP 实现消息传输。SOAP 是用于在应用程序之间进行通信的一种通信协议。因为是基于 XML 和HTTP 的，所以其独立于语言，独立于平台，并且因为 XML 的扩展性很好，所以基于 XML 的 SOAP 自然扩展性也不差。通过 SOAP 可以非常方便的解决互联网中消息互联互通的需求，其和其他的 Web 服务协议构建起 SOA 应用的技术基础。 下面来正式开始 ASP.NET Core 实现SOAP 服务端解析。

新建项目

首先新建一个ASP.NET Core Web Application -》 SOAPService 然后再模板里选择 Web API。然后我们再添加一个Class Library -》 CustomMiddleware

实现

下面我们来实现功能，首先在类库项目中添加以下引用

Install-Package Microsoft.AspNetCore.Http.Abstractions
Install-Package System.ServiceModel.Primitives
Install-Package System.Reflection.TypeExtensions
Install-Package System.ComponentModel

首先新建一个 ServiceDescription、ContractDescription和OperationDescription 类，这里需要注意的是ServiceDescription，ContractDescription和OperationDescription这里使用的是不能使用 System.ServiceModel.Description命名空间中的类型。它们是示例中简单的新类型。ServiceDescription.cspublic class ServiceDescription    {        public Type ServiceType { get; private set; }        public IEnumerable<ContractDescription> Contracts { get; private set; }        public IEnumerable<OperationDescription> Operations => Contracts.SelectMany(c => c.Operations);        public ServiceDescription(Type serviceType)        {            ServiceType = serviceType;            var contracts = new List<ContractDescription>();            foreach (var contractType in ServiceType.GetInterfaces())            {                foreach (var serviceContract in contractType.GetTypeInfo().GetCustomAttributes<ServiceContractAttribute>())                {                    contracts.Add(new ContractDescription(this, contractType, serviceContract));                }            }            Contracts = contracts;        }    }

ContractDescription.cs

public class ContractDescription    {        public ServiceDescription Service { get; private set; }        public string Name { get; private set; }        public string Namespace { get; private set; }        public Type ContractType { get; private set; }        public IEnumerable<OperationDescription> Operations { get; private set; }        public ContractDescription(ServiceDescription service, Type contractType, ServiceContractAttribute attribute)        {            Service = service;            ContractType = contractType;            Namespace = attribute.Namespace ?? "http://tempuri.org/"; // Namespace defaults to http://tempuri.org/             Name = attribute.Name ?? ContractType.Name; // Name defaults to the type name            var operations = new List<OperationDescription>();            foreach (var operationMethodInfo in ContractType.GetTypeInfo().DeclaredMethods)            {                foreach (var operationContract in operationMethodInfo.GetCustomAttributes<OperationContractAttribute>())                {                    operations.Add(new OperationDescription(this, operationMethodInfo, operationContract));                }            }            Operations = operations;        }    }OperationDescription.cspublic class OperationDescription    {        public ContractDescription Contract { get; private set; }        public string SoapAction { get; private set; }        public string ReplyAction { get; private set; }        public string Name { get; private set; }        public MethodInfo DispatchMethod { get; private set; }        public bool IsOneWay { get; private set; }        public OperationDescription(ContractDescription contract, MethodInfo operationMethod, OperationContractAttribute contractAttribute)        {            Contract = contract;            Name = contractAttribute.Name ?? operationMethod.Name;            SoapAction = contractAttribute.Action ?? $"{contract.Namespace.TrimEnd('/')}/{contract.Name}/{Name}";            IsOneWay = contractAttribute.IsOneWay;            ReplyAction = contractAttribute.ReplyAction;            DispatchMethod = operationMethod;        }    } 添加完成后下面来新建一个中间件 SOAPMiddleware ，对于新建中间件可以参考我之前的文章：http://www.cnblogs.com/linezero/p/5529767.htmlSOAPMiddleware.cs 代码如下：public class SOAPMiddleware    {        private readonly RequestDelegate _next;        private readonly Type _serviceType;        private readonly string _endpointPath;        private readonly MessageEncoder _messageEncoder;        private readonly ServiceDescription _service;        private IServiceProvider serviceProvider;        public SOAPMiddleware(RequestDelegate next, Type serviceType, string path, MessageEncoder encoder,IServiceProvider _serviceProvider)        {            _next = next;            _serviceType = serviceType;            _endpointPath = path;            _messageEncoder = encoder;            _service = new ServiceDescription(serviceType);            serviceProvider = _serviceProvider;        }        public async Task Invoke(HttpContext httpContext)        {            if (httpContext.Request.Path.Equals(_endpointPath, StringComparison.Ordinal))            {                Message responseMessage;                //读取Request请求信息                var requestMessage = _messageEncoder.ReadMessage(httpContext.Request.Body, 0x10000, httpContext.Request.ContentType);                var soapAction = httpContext.Request.Headers["SOAPAction"].ToString().Trim('\"');                if (!string.IsNullOrEmpty(soapAction))                {                    requestMessage.Headers.Action = soapAction;                }                //获取操作                var operation = _service.Operations.Where(o => o.SoapAction.Equals(requestMessage.Headers.Action, StringComparison.Ordinal)).FirstOrDefault();                if (operation == null)                {                    throw new InvalidOperationException($"No operation found for specified action: {requestMessage.Headers.Action}");                }                //获取注入的服务                var serviceInstance = serviceProvider.GetService(_service.ServiceType);                //获取操作的参数信息                var arguments = GetRequestArguments(requestMessage, operation);                // 执行操作方法                var responseObject = operation.DispatchMethod.Invoke(serviceInstance, arguments.ToArray());                var resultName = operation.DispatchMethod.ReturnParameter.GetCustomAttribute<MessageParameterAttribute>()?.Name ?? operation.Name + "Result";                var bodyWriter = new ServiceBodyWriter(operation.Contract.Namespace, operation.Name + "Response", resultName, responseObject);                responseMessage = Message.CreateMessage(_messageEncoder.MessageVersion, operation.ReplyAction, bodyWriter);                httpContext.Response.ContentType = httpContext.Request.ContentType;                httpContext.Response.Headers["SOAPAction"] = responseMessage.Headers.Action;                _messageEncoder.WriteMessage(responseMessage, httpContext.Response.Body);            }            else            {                await _next(httpContext);            }        }        private object[] GetRequestArguments(Message requestMessage, OperationDescription operation)        {            var parameters = operation.DispatchMethod.GetParameters();            var arguments = new List<object>();            // 反序列化请求包和对象            using (var xmlReader = requestMessage.GetReaderAtBodyContents())            {                // 查找的操作数据的元素                xmlReader.ReadStartElement(operation.Name, operation.Contract.Namespace);                for (int i = 0; i < parameters.Length; i++)                {                    var parameterName = parameters[i].GetCustomAttribute<MessageParameterAttribute>()?.Name ?? parameters[i].Name;                    xmlReader.MoveToStartElement(parameterName, operation.Contract.Namespace);                    if (xmlReader.IsStartElement(parameterName, operation.Contract.Namespace))                    {                        var serializer = new DataContractSerializer(parameters[i].ParameterType, parameterName, operation.Contract.Namespace);                        arguments.Add(serializer.ReadObject(xmlReader, verifyObjectName: true));                    }                }            }            return arguments.ToArray();        }    }    public static class SOAPMiddlewareExtensions    {        public static IApplicationBuilder UseSOAPMiddleware<T>(this IApplicationBuilder builder, string path, MessageEncoder encoder)        {            return builder.UseMiddleware<SOAPMiddleware>(typeof(T), path, encoder);        }        public static IApplicationBuilder UseSOAPMiddleware<T>(this IApplicationBuilder builder, string path, Binding binding)        {            var encoder = binding.CreateBindingElements().Find<MessageEncodingBindingElement>()?.CreateMessageEncoderFactory().Encoder;            return builder.UseMiddleware<SOAPMiddleware>(typeof(T), path, encoder);        }    }这里对于输出的消息做了一个封装，以输出具有正确的元素名称的消息的主体。添加一个 ServiceBodyWriter 类。public class ServiceBodyWriter : BodyWriter    {        string ServiceNamespace;        string EnvelopeName;        string ResultName;        object Result;        public ServiceBodyWriter(string serviceNamespace, string envelopeName, string resultName, object result) : base(isBuffered: true)        {            ServiceNamespace = serviceNamespace;            EnvelopeName = envelopeName;            ResultName = resultName;            Result = result;        }        protected override void OnWriteBodyContents(XmlDictionaryWriter writer)        {            writer.WriteStartElement(EnvelopeName, ServiceNamespace);            var serializer = new DataContractSerializer(Result.GetType(), ResultName, ServiceNamespace);            serializer.WriteObject(writer, Result);            writer.WriteEndElement();        }    }这里对于中间件整个就完成了。

服务端

在服务端使用，这里你也可以新建一个Web 项目。因为刚刚我们已经新建好了一个Web API项目，我们就直接拿来使用。首先添加 CustomMiddleware 引用在 SOAPService 中添加一个 CalculatorService 类这里我为了方便将接口契约也放在CalculatorService 中，你也可以新建一个接口。然后在 Startup.cs  的 ConfigureServices 中注入 CalculatorService

public void ConfigureServices(IServiceCollection services)

       {            // Add framework services.            services.AddMvc();
           services.AddScoped<CalculatorService>();
       }

在Configure 方法中加入中间件public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)        {            loggerFactory.AddConsole(Configuration.GetSection("Logging"));            loggerFactory.AddDebug();            //加入一个/CalculatorService.svc 地址，绑定Http            app.UseSOAPMiddleware<CalculatorService>("/CalculatorService.svc", new BasicHttpBinding());            app.UseMvc();        }这样就完成了服务端编写。

客户端

新建一个 Console Application -》SOAPClient添加如下引用：

Install-Package System.ServiceModel.PrimitivesInstall-Package System.Private.ServiceModelInstall-Package System.ServiceModel.Http

 Program代码如下：编写好以后，分别对应到目录使用dotnet run执行程序。成功建立了连接，也有返回。也就实现SOAP 的解析。 示例代码GitHub：https://github.com/linezero/Blog/tree/master/SOAPService 参考文档：https://blogs.msdn.microsoft.com/dotnet/2016/09/19/custom-asp-net-core-middleware-example/原文地址：http://www.cnblogs.com/linezero/p/aspnetcoresoap.html.NET社区新闻，深度好文，微信中搜索dotNET跨平台或扫描二维码关注