Como posso definir cabeçalhos com Silverlight GET HttpWebRequest?
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05-07-2019 - |
Pergunta
Fazendo um pedido para um serviço RESTful em Silverlight com HttpWebRequest funciona bem, desde que eu não adicionar cabeçalhos para o pedido.
Assim que eu adicionar um cabeçalho usando código como este
var webReq = (HttpWebRequest)WebRequest.Create(new Uri(_RemoteAddress, "GetProviderMetadata"));
webReq.Method = HttpMethodType.Get;
webReq.Headers["SomeToken"] = "someTokenValue";
Eu recebo a exceção colado na parte inferior desta questão, logo que EndGetResponse()
é chamado. Alguém sabe por que isso é? Adicionar cabeçalhos para obter solicitações parece funcionar bem em .NET normal, então eu estou supondo que é algum tipo de limitação Silverlight, mas não consigo encontrar qualquer documentação que esclarece.
{System.NotSupportedException ---> System.NotSupportedException: Specified method is not supported.
at System.Net.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)
at System.Net.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState)
at System.Net.AsyncHelper.<>c__DisplayClass2.<BeginOnUI>b__0(Object sendState)
--- End of inner exception stack trace ---
at System.Net.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
at System.Net.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
at System.Net.BrowserHttpWebRequest.<>c__DisplayClassd.<InvokeGetResponseCallback>b__b(Object state2)
at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)}
[System.NotSupportedException]: {System.NotSupportedException ---> System.NotSupportedException: Specified method is not supported.
at System.Net.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)
at System.Net.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState)
at System.Net.AsyncHelper.<>c__DisplayClass2.<BeginOnUI>b__0(Object sendState)
--- End of inner exception stack trace ---
at System.Net.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
at System.Net.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
at System.Net.BrowserHttpWebRequest.<>c__DisplayClassd.<InvokeGetResponseCallback>b__b(Object state2)
at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)}
_className: "System.NotSupportedException"
_data: {System.Collections.ListDictionaryInternal}
_dynamicMethods: null
_exceptionMethod: null
_exceptionMethodString: null
_helpURL: null
_HResult: -2146233067
_innerException: {System.NotSupportedException: Specified method is not supported.
at System.Net.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)
at System.Net.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState)
at System.Net.AsyncHelper.<>c__DisplayClass2.<BeginOnUI>b__0(Object sendState)}
_message: ""
_remoteStackIndex: 0
_remoteStackTraceString: null
_source: "System.Windows"
_stackTrace: {sbyte[192]}
_stackTraceString: null
_xcode: -532462766
_xptrs: 0
Data: {System.Collections.ListDictionaryInternal}
HelpLink: null
HResult: -2146233067
InnerException: {System.NotSupportedException: Specified method is not supported.
at System.Net.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)
at System.Net.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState)
at System.Net.AsyncHelper.<>c__DisplayClass2.<BeginOnUI>b__0(Object sendState)}
Message: ""
Source: "System.Windows"
StackTrace: " at System.Net.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)\r\n at System.Net.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)\r\n at Intellidimension.RdfEntity.Service.RemoteEntityServiceProviderClient.getProviderMetadataResponse(IAsyncResult result)\r\n at System.Net.BrowserHttpWebRequest.<>c__DisplayClassd.<InvokeGetResponseCallback>b__b(Object state2)\r\n at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)\r\n at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)\r\n at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)\r\n at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)"
System.Runtime.InteropServices._Exception.HelpLink: null
System.Runtime.InteropServices._Exception.Source: "System.Windows"
Solução
Silverlight só suporta configuração cabeçalhos utilizando o método POST não o método GET. Isto é devido a uma limitação na forma como a pilha TCP / IP é implementado em Silverlight. Ele usa as APIs de extensão do navegador em vez de ir diretamente contra APIs do sistema operacional hospedeiro.
Outras dicas
"HTTP Cliente" manipulação antes de chamá-lo de iniciar o seu WebRequest.
Como esta:
bool httpResult = WebRequest.RegisterPrefix("http://", WebRequestCreator.ClientHttp);
bool httpsResult = WebRequest.RegisterPrefix("https://", WebRequestCreator.ClientHttp);