diff --git a/Core/Core.cs b/Core/Core.cs
index 9d342a9..d71056c 100644
--- a/Core/Core.cs
+++ b/Core/Core.cs
@@ -66,6 +66,7 @@ namespace Kruzya.TelegramBot.Core
         {
             _configuration = configuration;
 
+            HookAppDomain();
             Start();
         }
 
@@ -156,5 +157,20 @@ namespace Kruzya.TelegramBot.Core
 
             return module;
         }
+
+        private void HookAppDomain()
+        {
+            AppDomain.CurrentDomain.AssemblyResolve += delegate(object? sender, ResolveEventArgs args)
+            {
+                var basePath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
+                string assemblyPath = Path.Combine(basePath, new AssemblyName(args.Name).Name + ".dll");
+                if (!File.Exists(assemblyPath))
+                {
+                    return null;
+                }
+
+                return Assembly.LoadFrom(assemblyPath);
+            };
+        }
     }
 }
diff --git a/Core/Core.csproj b/Core/Core.csproj
index 2d8933e..21c37b2 100644
--- a/Core/Core.csproj
+++ b/Core/Core.csproj
@@ -8,6 +8,10 @@
 
     <ItemGroup>
       <PackageReference Include="AleXr64.BotFramework" Version="0.0.17" />
+      <PackageReference Include="Microsoft.EntityFrameworkCore.Proxies" Version="3.1.2" />
+      <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="3.1.2" />
+      <PackageReference Include="Microsoft.Extensions.Hosting.Systemd" Version="3.1.2" />
+      <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="3.1.1" />
     </ItemGroup>
 
 </Project>
diff --git a/Core/DbResolverParameter.cs b/Core/DbResolverParameter.cs
new file mode 100644
index 0000000..58e8e51
--- /dev/null
+++ b/Core/DbResolverParameter.cs
@@ -0,0 +1,41 @@
+using System;
+using BotFramework;
+using Microsoft.EntityFrameworkCore;
+
+namespace Kruzya.TelegramBot.Core
+{
+    /// <summary>
+    /// Resolves the GUIDs from database to entities.
+    /// </summary>
+    /// <typeparam name="TResolvedEntity">Entity type</typeparam>
+    /// <typeparam name="TAppContext">Database context where entity should be finded</typeparam>
+    public class DbResolverParameter<TResolvedEntity, TAppContext> : IParameterParser<TResolvedEntity>
+        where TAppContext : DbContext
+        where TResolvedEntity : class
+    {
+        private TAppContext _dbContext;
+
+        public DbResolverParameter(TAppContext dbContext)
+        {
+            _dbContext = dbContext;
+        }
+        
+        public TResolvedEntity DefaultInstance()
+        {
+            return default(TResolvedEntity);
+        }
+
+        public bool TryGetValue(string text, out TResolvedEntity result)
+        {
+            result = null;
+            Guid id;
+            if (Guid.TryParse(text, out id))
+            {
+                result = _dbContext.Find<TResolvedEntity>(id);
+                return (result != null);
+            }
+
+            return false;
+        }
+    }
+}
\ No newline at end of file
diff --git a/Core/Extensions/RepositoryExtension.cs b/Core/Extensions/RepositoryExtension.cs
new file mode 100644
index 0000000..98bafd4
--- /dev/null
+++ b/Core/Extensions/RepositoryExtension.cs
@@ -0,0 +1,47 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace Kruzya.TelegramBot.Core.Extensions
+{
+    public static class RepositoryExtension
+    {
+        #region DbContext
+
+        /// <summary>
+        /// Marks the entity as created.
+        /// </summary>
+        /// <param name="dbContext"></param>
+        /// <param name="entity">Entity for marking as created.</param>
+        public static void MarkAsCreated(this DbContext dbContext, object entity) =>
+            dbContext.Entry(entity).State = EntityState.Added;
+
+        /// <summary>
+        /// Marks the entity as deleted.
+        /// </summary>
+        /// <param name="dbContext"></param>
+        /// <param name="entity">Entity for marking as deleted.</param>
+        public static void MarkAsDeleted(this DbContext dbContext, object entity) =>
+            dbContext.Entry(entity).State = EntityState.Deleted;
+
+        /// <summary>
+        /// Marks the entity as modified.
+        /// </summary>
+        /// <param name="dbContext"></param>
+        /// <param name="entity">Entity for marking as modified.</param>
+        public static void MarkAsModified(this DbContext dbContext, object entity) =>
+            dbContext.Entry(entity).State = EntityState.Modified;
+
+        #endregion
+
+        #region Repository
+
+        public static TEntity Create<TEntity>(this DbSet<TEntity> repository) where TEntity : class, new()
+        {
+            var entity = new TEntity();
+            repository.Add(entity);
+
+            return entity;
+        }
+
+        #endregion
+    }
+}
\ No newline at end of file
diff --git a/Core/Extensions/StartupExtension.cs b/Core/Extensions/StartupExtension.cs
new file mode 100644
index 0000000..66c357a
--- /dev/null
+++ b/Core/Extensions/StartupExtension.cs
@@ -0,0 +1,13 @@
+using System.Collections.Concurrent;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Kruzya.TelegramBot.Core.Extensions
+{
+    public static class StartupExtension
+    {
+        public static IServiceCollection AddQueue<T>(this IServiceCollection collection)
+        {
+            return collection.AddSingleton<ConcurrentQueue<T>>();
+        }
+    }
+}
\ No newline at end of file
diff --git a/Core/Program.cs b/Core/Program.cs
index f69b4b9..30931b0 100644
--- a/Core/Program.cs
+++ b/Core/Program.cs
@@ -12,6 +12,7 @@ namespace Kruzya.TelegramBot.Core
 
         public static IHostBuilder CreateHostBuilder(string[] args) =>
             Host.CreateDefaultBuilder(args)
+                .UseSystemd()
                 .ConfigureWebHostDefaults(webBuilder => { webBuilder.UseStartup<Startup>(); });
     }
 }
diff --git a/Core/Service/AbstractTimedHostedService.cs b/Core/Service/AbstractTimedHostedService.cs
new file mode 100644
index 0000000..30a784c
--- /dev/null
+++ b/Core/Service/AbstractTimedHostedService.cs
@@ -0,0 +1,76 @@
+using System;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using BotFramework;
+using Microsoft.Extensions.Logging;
+using Telegram.Bot.Exceptions;
+using Telegram.Bot.Types;
+
+namespace Kruzya.TelegramBot.Core.Service
+{
+    public abstract class AbstractTimedHostedService
+    {
+        private Timer _timer;
+        
+        protected readonly ILogger _logger;
+        protected readonly ITelegramBot _bot;
+        
+        protected virtual TimeSpan TimerPeriod => TimeSpan.FromSeconds(45);
+
+        protected AbstractTimedHostedService(ILogger logger, ITelegramBot bot)
+        {
+            _bot = bot;
+            _logger = logger;
+        }
+
+        #region IHostedService
+
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            _logger.LogInformation("Message sender service is starting.");
+            _timer = new Timer(Run, null, TimeSpan.Zero, TimeSpan.FromSeconds(1));
+
+            return Task.CompletedTask;
+        }
+
+        public Task StopAsync(CancellationToken cancellationToken)
+        {
+            _logger.LogInformation("Message sender service is stopping.");
+            _timer?.Change(Timeout.Infinite, 0);
+
+            return Task.CompletedTask;
+        }
+        
+        #endregion
+        #region IDisposable
+        /// <summary>
+        /// Disposes the timer.
+        /// </summary>
+        public void Dispose()
+        {
+            _timer?.Dispose();
+        }
+        #endregion
+
+        private async void Run(object state)
+        {
+            _timer?.Change(Timeout.Infinite, 0);
+
+            try
+            {
+                await OnRun();
+            }
+            finally
+            {
+                var timerPeriod = this.TimerPeriod;
+                _timer?.Change(timerPeriod, timerPeriod);
+            }
+        }
+        
+        protected virtual async Task OnRun()
+        {
+            await Task.Delay(500);
+        }
+    }
+}
\ No newline at end of file