azure - 在此情况下无法做出响应

Question

这是我在运行从 Asp.net 迁移到 Windows Azure Cloud 的 Web 项目时遇到的异常。如果我尝试运行 ASP.net 应用程序，这很好，但在迁移到 Windows Azure Cloud 后，我收到以下异常。我没有找到解决方案的线索，请有人做必要的事情..

**Exception:**
Server.GetLastError().GetBaseException()
{"Response is not available in this context."}
    [System.Web.HttpException]: {"Response is not available in this context."}
    Data: {System.Collections.ListDictionaryInternal}
    HelpLink: null
    InnerException: null
    Message: "Response is not available in this context."
    Source: "System.Web"

    StackTrace: "   at System.Web.UI.Page.get_Response()\r\n   at Writehome_aspxToXml(XmlWriterDelegator , Object , XmlObjectSerializerWriteContext , ClassDataContract )\r\n   at System.Runtime.Serialization.ClassDataContract.WriteXmlValue(XmlWriterDelegator xmlWriter, Object obj, XmlObjectSerializerWriteContext context)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.WriteDataContractValue(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeAndVerifyType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, Boolean verifyKnownType, RuntimeTypeHandle declaredTypeHandle, Type declaredType)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiType(XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle objectTypeHandle, Type objectType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle, Type declare
dType)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContextComplex.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle)\r\n   at WritePlaceHolderToXml(XmlWriterDelegator , Object , XmlObjectSerializerWriteContext , ClassDataContract )\r\n   at System.Runtime.Serialization.ClassDataContract.WriteXmlValue(XmlWriterDelegator xmlWriter, Object obj, XmlObjectSerializerWriteContext context)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.WriteDataContractValue(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.S
erializeAndVerifyType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, Boolean verifyKnownType, RuntimeTypeHandle declaredTypeHandle, Type declaredType)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiType(XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle objectTypeHandle, Type objectType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle, Type declaredType)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContextComplex.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle)\r\n   at WriteArrayOfControlToXml(XmlWriterDelegator , Object , XmlObjectSerializerWriteContext , Collection
DataContract )\r\n   at System.Runtime.Serialization.CollectionDataContract.WriteXmlValue(XmlWriterDelegator xmlWriter, Object obj, XmlObjectSerializerWriteContext context)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.WriteDataContractValue(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeAndVerifyType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, Boolean verifyKnownType, RuntimeTypeHandle declaredTypeHandle, Type declaredType)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiType(XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle objectTypeHandle, Type objectType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle, Type declaredType)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDec
laredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContextComplex.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle)\r\n   at WriteArrayOfanyTypeToXml(XmlWriterDelegator , Object , XmlObjectSerializerWriteContext , CollectionDataContract )\r\n   at System.Runtime.Serialization.CollectionDataContract.WriteXmlValue(XmlWriterDelegator xmlWriter, Object obj, XmlObjectSerializerWriteContext context)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.WriteDataContractValue(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithoutXsiType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle)\r\n   a
t System.Runtime.Serialization.XmlObjectSerializerWriteContext.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle)\r\n   at System.Runtime.Serialization.XmlObjectSerializerWriteContextComplex.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle)\r\n   at WriteSerializableSessionStateStoreDataToXml(XmlWriterDelegator , Object , XmlObjectSerializerWriteContext , ClassDataContract )\r\n   at System.Runtime.Serialization.ClassDataContract.WriteXmlValue(XmlWriterDelegator xmlWriter, Object obj, XmlObjectSerializerWriteContext context)\r\n   at System.Runtime.Serialization.NetDataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph, DataContract contract, Hashtable surrogateDataContracts)\r\n   at System.Runtime.Serialization.NetDataContractSerializer.InternalWr
iteObject(XmlWriterDelegator writer, Object graph)\r\n   at System.Runtime.Serialization.XmlObjectSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver)\r\n   at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver)\r\n   at System.Runtime.Serialization.XmlObjectSerializer.WriteObject(XmlDictionaryWriter writer, Object graph)\r\n   at Microsoft.ApplicationServer.Caching.NetDataContractCacheObjectSerializer.Serialize(Stream stream, Object value)\r\n   at Microsoft.ApplicationServer.Caching.DataCacheObjectSerializationProvider.SerializeUserObject(Object userObject, Boolean isCompressionEnabled, ValueFlagsVersion flagsType)\r\n   at Microsoft.ApplicationServer.Caching.SocketClientProtocol.SerializeValue(Object obj)\r\n   at Microsoft.ApplicationServer.Caching.SocketClientProtocol.PutAndUnlock(String key, Object value, DataCacheLockHandle lockHandle,
 TimeSpan timeout, DataCacheTag[] tags, String region, IMonitoringListener listener)\r\n   at Microsoft.ApplicationServer.Caching.DataCache.InternalPutAndUnlock(String key, Object value, DataCacheLockHandle lockHandle, TimeSpan timeout, DataCacheTag[] tags, String region, IMonitoringListener listener)\r\n   at Microsoft.ApplicationServer.Caching.DataCache.<>c__DisplayClass9c.<PutAndUnlock>b__9b()\r\n   at Microsoft.ApplicationServer.Caching.MonitoringListenerFactory.EmptyListener.Microsoft.ApplicationServer.Caching.IMonitoringListener.Listen[TResult](Func`1 innerDelegate)\r\n   at Microsoft.ApplicationServer.Caching.DataCache.PutAndUnlock(String key, Object value, DataCacheLockHandle lockHandle, TimeSpan timeout)\r\n   at Microsoft.Web.DistributedCache.DataCacheWrapper.PutAndUnlock(String key, Object value, DataCacheLockHandle lockHandle, TimeSpan timeout)\r\n   at Microsoft.Web.DistributedCache.DataCacheForwarderBase.<>c__DisplayClass1c.<PutAndUnlock>b__1b()\r\n   at Microsoft.Web.DistributedCache.DataCacheFo
rwarderBase.<>c__DisplayClass31`1.<PerformCacheOperation>b__30()\r\n   at Microsoft.Web.DistributedCache.DataCacheRetryWrapper.PerformCacheOperation(Action action)\r\n   at Microsoft.Web.DistributedCache.DataCacheForwarderBase.PerformCacheOperation[TResult](Func`1 func)\r\n   at Microsoft.Web.DistributedCache.DataCacheForwarderBase.PutAndUnlock(String key, Object value, DataCacheLockHandle lockHandle, TimeSpan timeout)\r\n   at Microsoft.Web.DistributedCache.BlobBasedSessionStoreProvider.SetAndReleaseItemExclusive(HttpContextBase context, String id, SessionStateStoreData item, Object lockId, Boolean newItem)\r\n   at Microsoft.Web.DistributedCache.DistributedCacheSessionStateStoreProvider.SetAndReleaseItemExclusive(HttpContext context, String id, SessionStateStoreData item, Object lockId, Boolean newItem)\r\n   at System.Web.SessionState.SessionStateModule.OnReleaseState(Object source, EventArgs eventArgs)\r\n   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Exec
ute()\r\n   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)"
    TargetSite: {System.Web.HttpResponse get_Response()}

Answer 1

如果您尝试执行 Azure 操作(例如在 Application_Start 方法中访问 blob)，就会发生这种情况。

这是因为 HttpContext.Current.Response 可以访问。Azure 使用 Response 对象进行日志记录。无论如何，如果您需要访问 Web 应用中的 blob 或执行任何其他 Azure 操作，并且即使没有 Response 对象(如 Application_Start 方法中所示)，也希望执行此操作。您只需将 HttpContext.Current 设置为 null，但方式很巧妙。

Application_Start如下

protected void Application_Start(object sender, EventArgs e)
{
    CloudStorageAccount.SetConfigurationSettingPublisher((configName, configSetter) =>
    {
        configSetter(RoleEnvironment.GetConfigurationSettingValue(configName));
    });

    using (new AzureContext())
    {
        CloudStorageAccount storageAccount = CloudStorageAccount.FromConfigurationSetting("BlobConnectionString");

        CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

        CloudBlobContainer container = blobClient.GetContainerReference("mycontainer");
        container.CreateIfNotExist();
        container.FetchAttributes();
    }
}

AzureContext 如下:

public class AzureContext : IDisposable
{
    HttpContext _oldHttpContext;
    bool _restoreOldHttpContext = false;


    public AzureContext(bool forceSettingContextToNull = false)
    {
        if (forceSettingContextToNull)
        {
            _oldHttpContext = HttpContext.Current;
            HttpContext.Current = null;
            _restoreOldHttpContext = true;
        }
        else
        {
            try
            {
                HttpResponse response = HttpContext.Current.Response;
            }
            catch (HttpException)
            {
                _oldHttpContext = HttpContext.Current;
                HttpContext.Current = null;
                _restoreOldHttpContext = true;
            }
        }
    }


    public void Dispose(bool disposing)
    {
        if (disposing)
        {
            if (_restoreOldHttpContext)
            {
                HttpContext.Current = _oldHttpContext;
            }
        }
    }


    public void Dispose()
    {
        Dispose(true);
    }


    ~AzureContext()
    {
        Dispose(false);
    }
}

有关更多信息，请查看 Azure and Response is not available in this context

希望这对您有帮助。