use Diagnostics event feature to send the message after transaction commited for Sql Server.

src/DotNetCore.CAP.SqlServer/CAP.SqlServerCapOptionsExtension.cs

@@ -4,6 +4,7 @@
 using System;
 using DotNetCore.CAP.Processor;
 using DotNetCore.CAP.SqlServer;
+using DotNetCore.CAP.SqlServer.Diagnostics;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -22,6 +23,7 @@ namespace DotNetCore.CAP
         public void AddServices(IServiceCollection services)
         {
             services.AddSingleton<CapDatabaseStorageMarkerService>();
+            services.AddSingleton<DiagnosticProcessorObserver>();
             services.AddSingleton<IStorage, SqlServerStorage>();
             services.AddSingleton<IStorageConnection, SqlServerStorageConnection>();
 

src/DotNetCore.CAP.SqlServer/Diagnostics/DiagnosticObserver.cs

+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Data.SqlClient;
+using System.Reflection;
+using DotNetCore.CAP.Models;
+
+namespace DotNetCore.CAP.SqlServer.Diagnostics
+{
+    internal class DiagnosticObserver : IObserver<KeyValuePair<string, object>>
+    {
+        private readonly IDispatcher _dispatcher;
+        private readonly ConcurrentDictionary<Guid, List<CapPublishedMessage>> _bufferList;
+
+        public DiagnosticObserver(IDispatcher dispatcher,
+            ConcurrentDictionary<Guid, List<CapPublishedMessage>> bufferList)
+        {
+            _dispatcher = dispatcher;
+            _bufferList = bufferList;
+        }
+
+        private const string SqlClientPrefix = "System.Data.SqlClient.";
+
+        public const string SqlAfterCommitTransaction = SqlClientPrefix + "WriteTransactionCommitAfter";
+        public const string SqlErrorCommitTransaction = SqlClientPrefix + "WriteTransactionCommitError";
+
+        public void OnCompleted()
+        {
+
+        }
+
+        public void OnError(Exception error)
+        {
+
+        }
+
+        public void OnNext(KeyValuePair<string, object> evt)
+        {
+            if (evt.Key == SqlAfterCommitTransaction)
+            {
+                var sqlConnection = (SqlConnection) GetProperty(evt.Value, "Connection");
+                var transactionKey = sqlConnection.ClientConnectionId;
+                if (_bufferList.TryRemove(transactionKey, out var msgList))
+                {
+                    foreach (var message in msgList)
+                    {
+                        _dispatcher.EnqueueToPublish(message);
+                    }
+                }
+            }
+            else if (evt.Key == SqlErrorCommitTransaction)
+            {
+                var sqlConnection = (SqlConnection) GetProperty(evt.Value, "Connection");
+                var transactionKey = sqlConnection.ClientConnectionId;
+
+                _bufferList.TryRemove(transactionKey, out _);
+            }
+        }
+
+        static object GetProperty(object _this, string propertyName)
+        {
+            return _this.GetType().GetTypeInfo().GetDeclaredProperty(propertyName)?.GetValue(_this);
+        }
+    }
+}
\ No newline at end of file

src/DotNetCore.CAP.SqlServer/Diagnostics/DiagnosticProcessorObserver.cs

+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Diagnostics;
+using DotNetCore.CAP.Models;
+
+namespace DotNetCore.CAP.SqlServer.Diagnostics
+{
+    public class DiagnosticProcessorObserver : IObserver<DiagnosticListener>
+    {
+        private readonly IDispatcher _dispatcher;
+        public const string DiagnosticListenerName = "SqlClientDiagnosticListener";
+
+        public ConcurrentDictionary<Guid, List<CapPublishedMessage>> BufferList { get; }
+
+        public DiagnosticProcessorObserver(IDispatcher dispatcher)
+        {
+            _dispatcher = dispatcher;
+            BufferList = new ConcurrentDictionary<Guid, List<CapPublishedMessage>>();
+        }
+
+        public void OnCompleted()
+        {
+        }
+
+        public void OnError(Exception error)
+        {
+        }
+
+        public void OnNext(DiagnosticListener listener)
+        {
+            if (listener.Name == DiagnosticListenerName)
+            {
+                listener.Subscribe(new DiagnosticObserver(_dispatcher, BufferList));
+            }
+        }
+    }
+}
\ No newline at end of file

src/DotNetCore.CAP.SqlServer/ICapTransaction.SqlServer.cs

 // Copyright (c) .NET Core Community. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
+using System;
+using System.Collections.Generic;
 using System.Data;
-using System.Diagnostics;
+using System.Data.SqlClient;
+using DotNetCore.CAP.Models;
+using DotNetCore.CAP.SqlServer.Diagnostics;
 using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Storage;
 
@@ -11,50 +15,68 @@ namespace DotNetCore.CAP
 {
     public class SqlServerCapTransaction : CapTransactionBase
     {
-        public SqlServerCapTransaction(IDispatcher dispatcher) : base(dispatcher)
+        private readonly DiagnosticProcessorObserver _diagnosticProcessor;
+
+        public SqlServerCapTransaction(IDispatcher dispatcher,
+            DiagnosticProcessorObserver diagnosticProcessor) : base(dispatcher)
         {
+            _diagnosticProcessor = diagnosticProcessor;
         }
 
-        public override void Commit()
+        protected override void AddToSent(CapPublishedMessage msg)
         {
-            Debug.Assert(DbTransaction != null);
-
-            switch (DbTransaction)
+            var transactionKey = ((SqlConnection)((IDbTransaction)DbTransaction).Connection).ClientConnectionId;
+            if (_diagnosticProcessor.BufferList.TryGetValue(transactionKey, out var list))
             {
-                case IDbTransaction dbTransaction:
-                    dbTransaction.Commit();
-                    break;
-                case IDbContextTransaction dbContextTransaction:
-                    dbContextTransaction.Commit();
-                    break;
+                list.Add(msg);
             }
+            else
+            {
+                var msgList = new List<CapPublishedMessage>(1) { msg };
+                _diagnosticProcessor.BufferList.TryAdd(transactionKey, msgList);
+            }
+        }
 
-            Flush();
+        public override void Commit()
+        {
+            throw new NotImplementedException();
         }
 
         public override void Rollback()
         {
-            Debug.Assert(DbTransaction != null);
-
-            switch (DbTransaction)
-            {
-                case IDbTransaction dbTransaction:
-                    dbTransaction.Rollback();
-                    break;
-                case IDbContextTransaction dbContextTransaction:
-                    dbContextTransaction.Rollback();
-                    break;
-            }
+            throw new NotImplementedException();
         }
 
         public override void Dispose()
         {
-            (DbTransaction as IDbTransaction)?.Dispose();
+
         }
     }
 
     public static class CapTransactionExtensions
     {
+        public static ICapTransaction Begin(this ICapTransaction transaction,
+            IDbTransaction dbTransaction, bool autoCommit = false)
+        {
+            transaction.DbTransaction = dbTransaction;
+            transaction.AutoCommit = autoCommit;
+
+            return transaction;
+        }
+
+        public static IDbTransaction BeginTransaction(this IDbConnection dbConnection,
+            ICapPublisher publisher, bool autoCommit = false)
+        {
+            if (dbConnection.State == ConnectionState.Closed)
+            {
+                dbConnection.Open();
+            }
+
+            var dbTransaction = dbConnection.BeginTransaction();
+            var capTransaction = publisher.Transaction.Begin(dbTransaction, autoCommit);
+            return (IDbTransaction)capTransaction.DbTransaction;
+        }
+
         public static ICapTransaction Begin(this ICapTransaction transaction,
             IDbContextTransaction dbTransaction, bool autoCommit = false)
         {
@@ -64,7 +86,7 @@ namespace DotNetCore.CAP
             return transaction;
         }
 
-        public static IDbContextTransaction BeginAndJoinToTransaction(this DatabaseFacade database,
+        public static IDbContextTransaction BeginTransaction(this DatabaseFacade database,
             ICapPublisher publisher, bool autoCommit = false)
         {
             var trans = database.BeginTransaction();

src/DotNetCore.CAP.SqlServer/IStorage.SqlServer.cs

@@ -4,10 +4,12 @@
 using System;
 using System.Data;
 using System.Data.SqlClient;
+using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
 using Dapper;
 using DotNetCore.CAP.Dashboard;
+using DotNetCore.CAP.SqlServer.Diagnostics;
 using Microsoft.Extensions.Logging;
 
 namespace DotNetCore.CAP.SqlServer
@@ -18,12 +20,15 @@ namespace DotNetCore.CAP.SqlServer
         private readonly IDbConnection _existingConnection = null;
         private readonly ILogger _logger;
         private readonly SqlServerOptions _options;
+        private readonly DiagnosticProcessorObserver _diagnosticProcessorObserver;
 
         public SqlServerStorage(ILogger<SqlServerStorage> logger,
             CapOptions capOptions,
-            SqlServerOptions options)
+            SqlServerOptions options,
+            DiagnosticProcessorObserver diagnosticProcessorObserver)
         {
             _options = options;
+            _diagnosticProcessorObserver = diagnosticProcessorObserver;
             _logger = logger;
             _capOptions = capOptions;
         }
@@ -53,6 +58,8 @@ namespace DotNetCore.CAP.SqlServer
             }
 
             _logger.LogDebug("Ensuring all create database tables script are applied.");
+
+            DiagnosticListener.AllListeners.Subscribe(_diagnosticProcessorObserver);
         }
 
         protected virtual string CreateDbTablesScript(string schema)

src/DotNetCore.CAP.SqlServer/IStorageTransaction.SqlServer.cs

@@ -14,7 +14,6 @@ namespace DotNetCore.CAP.SqlServer
     {
         private readonly IDbConnection _dbConnection;
 
-        private readonly IDbTransaction _dbTransaction;
         private readonly string _schema;
 
         public SqlServerStorageTransaction(SqlServerStorageConnection connection)
@@ -24,7 +23,6 @@ namespace DotNetCore.CAP.SqlServer
 
             _dbConnection = new SqlConnection(options.ConnectionString);
             _dbConnection.Open();
-            _dbTransaction = _dbConnection.BeginTransaction(IsolationLevel.ReadCommitted);
         }
 
         public void UpdateMessage(CapPublishedMessage message)
@@ -36,7 +34,7 @@ namespace DotNetCore.CAP.SqlServer
 
             var sql =
                 $"UPDATE [{_schema}].[Published] SET [Retries] = @Retries,[Content] = @Content,[ExpiresAt] = @ExpiresAt,[StatusName]=@StatusName WHERE Id=@Id;";
-            _dbConnection.Execute(sql, message, _dbTransaction);
+            _dbConnection.Execute(sql, message);
         }
 
         public void UpdateMessage(CapReceivedMessage message)
@@ -48,18 +46,16 @@ namespace DotNetCore.CAP.SqlServer
 
             var sql =
                 $"UPDATE [{_schema}].[Received] SET [Retries] = @Retries,[Content] = @Content,[ExpiresAt] = @ExpiresAt,[StatusName]=@StatusName WHERE Id=@Id;";
-            _dbConnection.Execute(sql, message, _dbTransaction);
+            _dbConnection.Execute(sql, message);
         }
 
         public Task CommitAsync()
         {
-            _dbTransaction.Commit();
             return Task.CompletedTask;
         }
 
         public void Dispose()
         {
-            _dbTransaction.Dispose();
             _dbConnection.Dispose();
         }
     }

test/DotNetCore.CAP.SqlServer.Test/DatabaseTestHost.cs

@@ -2,16 +2,18 @@ using System;
 using System.Data;
 using System.Data.SqlClient;
 using Dapper;
+using DotNetCore.CAP.SqlServer.Diagnostics;
 using Microsoft.Extensions.Logging;
 using Moq;
 
 namespace DotNetCore.CAP.SqlServer.Test
 {
-    public abstract class DatabaseTestHost:IDisposable
+    public abstract class DatabaseTestHost : IDisposable
     {
         protected ILogger<SqlServerStorage> Logger;
         protected CapOptions CapOptions;
         protected SqlServerOptions SqlSeverOptions;
+        protected DiagnosticProcessorObserver DiagnosticProcessorObserver;
 
         public bool SqlObjectInstalled;
 
@@ -23,6 +25,8 @@ namespace DotNetCore.CAP.SqlServer.Test
                 .SetupProperty(x => x.ConnectionString, ConnectionUtil.GetConnectionString())
                 .Object;
 
+            DiagnosticProcessorObserver = new Mock<DiagnosticProcessorObserver>().Object;
+
             InitializeDatabase();
         }
 
@@ -42,7 +46,7 @@ IF NOT EXISTS (SELECT * FROM sysdatabases WHERE name = N'{databaseName}')
 CREATE DATABASE [{databaseName}];");
             }
 
-            new SqlServerStorage(Logger, CapOptions, SqlSeverOptions).InitializeAsync().GetAwaiter().GetResult();
+            new SqlServerStorage(Logger, CapOptions, SqlSeverOptions, DiagnosticProcessorObserver).InitializeAsync().GetAwaiter().GetResult();
             SqlObjectInstalled = true;
         }