为什么我的 WCF 数据服务在我第二次运行时无法启动？

Question

我使用 Visual Studio 2015 创建了一个包含 WCF 数据服务的 ASP.NET 应用，基于 the AdventureWorks2014 OLTP，遵循 this walkthrough。

当我构建应用程序并在调试器（在 IIS Express 上）中运行它时，服务加载正常，我看到 XML 元数据显示在我的浏览器中，并且可以进一步请求子路径以查看我的数据库的行。只要调试会话继续，我就可以继续提出此类请求。

只要我停止调试器并重新启动它，中间没有重新构建，我的浏览器就会显示错误：

找不到类型“AdventureWorks.Internal.WebService.DataService”，作为 ServiceHost 指令中的服务属性值提供，或在配置元素 system.serviceModel/serviceHostingEnvironment/serviceActivations 中提供。

[InvalidOperationException: The type 'AdventureWorks.Internal.WebService.DataService', provided as the Service attribute value in the ServiceHost directive, or provided in the configuration element system.serviceModel/serviceHostingEnvironment/serviceActivations could not be found.]
   System.ServiceModel.Activation.ServiceHostFactory.CreateServiceHost(String constructorString, Uri[] baseAddresses) +741
   System.ServiceModel.HostingManager.CreateService(String normalizedVirtualPath, EventTraceActivity eventTraceActivity) +1417
   System.ServiceModel.HostingManager.ActivateService(ServiceActivationInfo serviceActivationInfo, EventTraceActivity eventTraceActivity) +53
   System.ServiceModel.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath, EventTraceActivity eventTraceActivity) +660

[ServiceActivationException: The service '/DataService.svc' cannot be activated due to an exception during compilation.  The exception message is: The type 'AdventureWorks.Internal.WebService.DataService', provided as the Service attribute value in the ServiceHost directive, or provided in the configuration element system.serviceModel/serviceHostingEnvironment/serviceActivations could not be found..]
   System.Runtime.AsyncResult.End(IAsyncResult result) +386
   System.ServiceModel.Activation.HostedHttpRequestAsyncResult.End(IAsyncResult result) +174
   System.ServiceModel.Activation.ServiceHttpHandler.EndProcessRequest(IAsyncResult result) +7
   System.Web.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar) +129

当我在 Visual Studio 2015 或 2017 中进行开发时会发生这种情况。 我将 Windows 10 与面向 .NET Framework 4.6.1 的 ASP.NET 应用程序一起使用。

DataService.svc:

<%@ ServiceHost Language="C#" Factory="System.ServiceModel.Activation.WebServiceHostFactory, System.ServiceModel.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" Service="AdventureWorks.Internal.WebService.DataService" %>

DataService.svc.cs:

namespace AdventureWorks.Internal.WebService
{
    //[ServiceBehavior(IncludeExceptionDetailInFaults = true)]
    public class DataService : DataService<AdventureWorksDatabaseEntities>
    {
        // This method is called only once to initialize service-wide policies.
        public static void InitializeService(DataServiceConfiguration config)
        {
            config.SetEntitySetAccessRule("*", EntitySetRights.All);
            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V3;
        }
    }
}

Web.config:

<?xml version="1.0" encoding="utf-8"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <system.web>
    <compilation debug="true" targetFramework="4.6.1" />
    <httpRuntime targetFramework="4.6.1" />
    <httpModules>
      <add name="ApplicationInsightsWebTracking" type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web" />
    </httpModules>
  </system.web>
  <system.codedom>
    <compilers>
      <compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:6 /nowarn:1659;1699;1701" />
      <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:14 /nowarn:41008 /define:_MYTYPE=\&quot;Web\&quot; /optionInfer+" />
    </compilers>
  </system.codedom>
  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
    <modules>
      <remove name="ApplicationInsightsWebTracking" />
      <add name="ApplicationInsightsWebTracking" type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web" preCondition="managedHandler" />
    </modules>
  </system.webServer>
  <connectionStrings>
    <add name="AdventureWorksDatabaseEntities" connectionString="metadata=res://*/DataModel.csdl|res://*/DataModel.ssdl|res://*/DataModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=(LocalDB)\MSSQLLocalDB;attachdbfilename=|DataDirectory|\AdventureWorksDatabase.mdf;integrated security=True;connect timeout=30;MultipleActiveResultSets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" />
  </connectionStrings>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="v13.0" />
      </parameters>
    </defaultConnectionFactory>
  </entityFramework>
  <system.serviceModel>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
  </system.serviceModel>
</configuration>

Answer 1

由于命名空间不一致而发生此错误。请检查所有命名空间。它应该工作。