SoapRpcMethodAttribute.OneWay属性

为方法添加将OneWay属性并设置为true时，客户端将立即返回，不能接收返回值，并且也不毁的到依法的任何异常通知
该属性位于System.Web.Service.Protocols命名空间下

[WebMethod]
[SoapRpcMethod(OneWay=true)]
public void StartLongOperation()
{
 /////
}

如果为一个有返回值的方法添加OneWay属性，编译时并不会抛出错误，但是将无法引用服务，
如果调用测试页，会得到一下结果

One-way methods cannot have return values.
Parameter name: methodInfo

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentException: One-way methods cannot have return values.
Parameter name: methodInfo

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[ArgumentException: One-way methods cannot have return values.
            Parameter name: methodInfo]
            System.Web.Services.Protocols.SoapReflector.ReflectMethod(LogicalMethodInfo methodInfo, Boolean client, XmlReflectionImporter xmlImporter, SoapReflectionImporter soapImporter, String defaultNs) +4643
            [InvalidOperationException: Method FavoriteService.add can not be reflected.]
            System.Web.Services.Protocols.SoapReflector.ReflectMethod(LogicalMethodInfo methodInfo, Boolean client, XmlReflectionImporter xmlImporter, SoapReflectionImporter soapImporter, String defaultNs) +6633
            System.Web.Services.Description.SoapProtocolReflector.ReflectMethod() +134
            System.Web.Services.Description.ProtocolReflector.ReflectBinding(ReflectedBinding reflectedBinding) +2511
            System.Web.Services.Description.ProtocolReflector.Reflect() +626
            System.Web.Services.Description.ServiceDescriptionReflector.ReflectInternal(ProtocolReflector[] reflectors) +560
            System.Web.Services.Description.ServiceDescriptionReflector.Reflect(Type type, String url) +117
            System.Web.Services.Protocols.DocumentationServerType..ctor(Type type, String uri) +159
            System.Web.Services.Protocols.DocumentationServerProtocol.Initialize() +335
            System.Web.Services.Protocols.ServerProtocolFactory.Create(Type type, HttpContext context, HttpRequest request, HttpResponse response, Boolean& abortProcessing) +99
            [InvalidOperationException: Unable to handle request.]
            System.Web.Services.Protocols.ServerProtocolFactory.Create(Type type, HttpContext context, HttpRequest request, HttpResponse response, Boolean& abortProcessing) +258
            System.Web.Services.Protocols.WebServiceHandlerFactory.CoreGetHandler(Type type, HttpContext context, HttpRequest request, HttpResponse response) +93
            [InvalidOperationException: Failed to handle request.]
            System.Web.Services.Protocols.WebServiceHandlerFactory.CoreGetHandler(Type type, HttpContext context, HttpRequest request, HttpResponse response) +240
            System.Web.Services.Protocols.WebServiceHandlerFactory.GetHandler(HttpContext context, String verb, String url, String filePath) +106
            System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, VirtualPath path, String pathTranslated, Boolean useAppConfig) +328
            System.Web.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +139
            System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +146
            

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Version Information: Microsoft .NET Framework Version:2.0.50727.42; ASP.NET Version:2.0.50727.42