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Azure在弹性事务中未能将事务封送入传播令牌（适用于MSDTC）

azuretransactionstransactionscopedistributed-transactionsmsdtc
7
在Windows Azure中，我们将两个ASP.NET WebAPI项目作为应用程序服务托管。我们需要在此启用分布式事务。我们在一个API中启动事务。然后，在该事务作用域内，我们获取该事务的传播令牌，并在另一个API调用期间将其作为标头发送。代码如下所示。
[HttpGet]
[Route("api/Test/Transaction/Commit")]
public async Task<string> Commit()
{
    using (var scope = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions
    {
        IsolationLevel = IsolationLevel.ReadCommitted
    },
    TransactionScopeAsyncFlowOption.Enabled))
    {
        // cross app domain call
        using (var client = new HttpClient())
        {
            using (var request = new HttpRequestMessage(HttpMethod.Get, ConfigurationManager.AppSettings["IdentityServerUri"] + "api/Test/Transaction/NoCommit"))
            {
                // forward transaction token
                request.AddTransactionPropagationToken();
                var response = await client.SendAsync(request);
                response.EnsureSuccessStatusCode();
            }
        }
        this.Repository.Insert(new Currency { Ccy = "x", IsoCode = "XIS", Name = "XYZ", CurrencyId = 9 });
        await this.Repository.SaveChangesAsync();

        scope.Complete();
        return "value";
    }
}

public static class HttpRequestMessageExtension
{
    public static void AddTransactionPropagationToken(this HttpRequestMessage request)
    {
        if (Transaction.Current != null)
        {
            var token = TransactionInterop.GetTransmitterPropagationToken(Transaction.Current);
            request.Headers.Add("TransactionToken", Convert.ToBase64String(token));
        }
    }
}

在我们调用的api(...api/Test/Transaction/NoCommit)内部，它位于事务范围内，在其中获取来自标头的事务的编组传播令牌，并使用它创建该事务的实例并使用该事务实例化TransactionScope。稍后，我们使用此事务范围来完成该事务。我们引入了一个操作筛选器来应用此操作，并将该筛选器添加到负责该api调用的操作中。该api和操作筛选器的代码如下所示。
    [HttpGet]
    [EnlistToDistributedTransactionActionFilter]
    [Route("api/Test/Transaction/NoCommit")]
    public async Task<string> NoCommit()
    {
        this.Repository.Insert(new Client
        {
            Name = "Test",
            AllowedOrigin = "*",
            Active = true,
            ClientGuid = Guid.NewGuid(),
            RefreshTokenLifeTime = 0,
            ApplicationType = ApplicationTypes.JavaScript,
            Secret = "ffff",
            Id = "Test"
        }
        );
        await this.Repository.SaveChangesAsync();
        return "value";
    }

public class EnlistToDistributedTransactionActionFilter : ActionFilterAttribute
{
    private const string TransactionId = "TransactionToken";

    /// <summary>
    /// Retrieve a transaction propagation token, create a transaction scope and promote the current transaction to a distributed transaction.
    /// </summary>
    /// <param name="actionContext">The action context.</param>
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
            if (actionContext.Request.Headers.Contains(TransactionId))
            {
                var values = actionContext.Request.Headers.GetValues(TransactionId);
                if (values != null && values.Any())
                {
                    byte[] transactionToken = Convert.FromBase64String(values.FirstOrDefault());
                    var transaction = TransactionInterop.GetTransactionFromTransmitterPropagationToken(transactionToken);
                    var transactionScope = new TransactionScope(transaction, TransactionScopeAsyncFlowOption.Enabled);

                    actionContext.Request.Properties.Add(TransactionId, transactionScope);
                }
            }            
    }

    /// <summary>
    /// Rollback or commit transaction.
    /// </summary>
    /// <param name="actionExecutedContext">The action executed context.</param>
    public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
    {
            if (actionExecutedContext.Request.Properties.Keys.Contains(TransactionId))
            {
                var transactionScope = actionExecutedContext.Request.Properties[TransactionId] as TransactionScope;
                if (transactionScope != null)
                {
                    if (actionExecutedContext.Exception != null)
                    {
                        Transaction.Current.Rollback();
                    }
                    else
                    {
                        transactionScope.Complete();
                    }

                    transactionScope.Dispose();
                    actionExecutedContext.Request.Properties[TransactionId] = null;
                }
            }                      
    }
}

因此，如果在该事务范围内（无论是第一个 API 还是第二个 API 中）发生任何异常，都会在此调用（api/Test/Transaction/Commit）期间回滚两个 API 所做的所有数据库更改。本地工作正常，因为本地支持 MSDTC。但在 Azure 中没有 MSDTC 支持。在 Azure 中，我们从弹性事务中获得支持。因此，当我们尝试从第一个服务器获取传播令牌的事务时，我们会收到异常。所以当我们尝试执行以下代码时： var transaction = TransactionInterop.GetTransactionFromTransmitterPropagationToken(transactionToken); 我们会收到带有消息“值不在预期范围内”的异常。这篇文章说，此方法需要 System.Transactions 通过 MSDTC 进行升级，但对于弹性事务，我们如何使其工作？对于弹性事务，我们需要将事务编组为传播令牌。如何做到这一点？正在寻找解决方案。
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