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.cs

public 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.cs

public 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.html

SOAPMiddleware.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.Primitives
Install-Package System.Private.ServiceModel
Install-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

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