c# - IReliableQueue 入队序列化错误

Question

我在我的有状态服务结构应用程序中使用可靠队列。当我尝试将一个项目入队时，入队方法抛出异常

使用的代码是

 protected override async Task RunAsync(CancellationToken cancellationToken)
        {
            ICommand myItem = new CreateCommand()
            {
                Data = "Sample Data",
                Id = Guid.NewGuid(),
                TenentName = "SampleTenant"
            };
            var myQueue = await this.StateManager.GetOrAddAsync<IReliableQueue<ICommand>>("CommandQueue");
            using (var tx = StateManager.CreateTransaction())
            {
                await myQueue.EnqueueAsync(tx, myItem, TimeSpan.FromSeconds(4), cancellationToken);
                await tx.CommitAsync();
            }
            using (var tx = StateManager.CreateTransaction())
            {
                var dq = await myQueue.TryDequeueAsync(tx);
                await tx.CommitAsync();
            }
        }
    }

    public interface ICommand
    {
        Guid Id { get; set; }
        string TenentName { get; set; }
    }


    public class CreateCommand : ICommand
    {
        public Guid Id { get; set; }
        public string TenentName { get; set; }
        public string Data { get; set; }
    }

在 myQueue.EnqueueAsync 上，它抛出异常

Type 'TestService.CreateCommand' with data contract name 'CreateCommand:http://schemas.datacontract.org/2004/07/TestService' is not expected. Consider using a DataContractResolver if you are using DataContractSerializer or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to the serializer.

堆栈跟踪

at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeAndVerifyType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, Boolean verifyKnownType, RuntimeTypeHandle declaredTypeHandle, Type declaredType) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiTypeAtTopLevel(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle originalDeclaredTypeHandle, Type graphType) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.XmlObjectSerializer.WriteObject(XmlDictionaryWriter writer, Object graph) at Microsoft.ServiceFabric.Replicator.DataContractStateSerializer1.Write(T
value, BinaryWriter binaryWriter) at
System.Fabric.Store.TStore5.GetValueBytes(TValue currentValue, TValue newValue) at System.Fabric.Store.TStore5.<AddAsync>d__4.MoveNext()
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
task) at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task) at
Microsoft.ServiceFabric.Data.Collections.DistributedQueue1.d__9.MoveNext() at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
at TestService.TestService.d__2.MoveNext() in D:\Projects\Local\ReliableSerialization\Application1\TestService\TestService.cs:line 51 at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.ServiceFabric.Services.Runtime.StatefulServiceReplicaAdapter.d__f.MoveNext()

当我更改代码以使用具体类型时，它工作正常。

以我为例 IReliableQueue<CreateCommand>

它运行良好。

我的代码引用:https://github.com/Azure-Samples/service-fabric-dotnet-iot/blob/master/src/gateway/IoTProcessorManagement.Common/WorkManagement/WorkManager.cs

Answer 1

您的类型缺少 DataContract 和 DataMember 属性，并且由于数据协定序列化工作方式的实现，您不能将 DataContract 属性放在接口(interface)上。缺少数据协定属性可能导致难以追踪错误，因为 Service Fabric 将在内部存储对对象的引用并在您出列时返回该引用，但在提交时将对象发送到辅助对象时序列化该对象。当您忘记上述属性时，您会看到它有时似乎可以工作，但要么会抛出提交事务，要么您将拥有看似良好的填充对象，直到服务重新启动(对于升级，如果该节点去下来，或其他一些原因)然后将是空的(缺少属性的字段将为空/默认)。

要在数据协定中利用多态性，您可以使用基类和 KnownType 属性。这就是您的示例在添加删除命令后的样子。

[DataContract]
[KnownType(typeof(CreateCommand))]
[KnownType(typeof(DeleteCommand))]
public class BaseCommand
{
    [DataMember]
    public Guid Id { get; set; }

    [DataMember]
    public string TenentName { get; set; }
}

[DataContract]
public class CreateCommand : BaseCommand
{
    [DataMember]
    public string Data { get; set; }
}

[DataContract]
public class DeleteCommand : BaseCommand
{
    [DataMember]
    public string SomeOtherData { get; set; }
}

另请注意，已知类型属性支持传入函数以编程方式发现子类型，但请勿使用它，因为它会以奇怪且难以诊断的方式破坏可升级性。