diff --git a/src/Intersvyaz.Core/Class1.cs b/src/Intersvyaz.Core/Class1.cs
deleted file mode 100644
index 326d1b4..0000000
--- a/src/Intersvyaz.Core/Class1.cs
+++ /dev/null
@@ -1,12 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace Intersvyaz.Core
-{
-    public class Class1
-    {
-    }
-}
diff --git a/src/Intersvyaz.Core/Intersvyaz.Core.csproj b/src/Intersvyaz.Core/Intersvyaz.Core.csproj
index 47ab5ae..108eaa5 100644
--- a/src/Intersvyaz.Core/Intersvyaz.Core.csproj
+++ b/src/Intersvyaz.Core/Intersvyaz.Core.csproj
@@ -120,8 +120,9 @@
     <RestoreProjectStyle>PackageReference</RestoreProjectStyle>
   </PropertyGroup>
   <ItemGroup>
-    <Compile Include="Class1.cs" />
+    <Compile Include="Models\SessionData.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="Services\ISessionService.cs" />
     <EmbeddedResource Include="Properties\Intersvyaz.Core.rd.xml" />
   </ItemGroup>
   <ItemGroup>
@@ -129,6 +130,7 @@
       <Version>6.2.8</Version>
     </PackageReference>
   </ItemGroup>
+  <ItemGroup />
   <PropertyGroup Condition=" '$(VisualStudioVersion)' == '' or '$(VisualStudioVersion)' &lt; '14.0' ">
     <VisualStudioVersion>14.0</VisualStudioVersion>
   </PropertyGroup>
diff --git a/src/Intersvyaz.Core/Models/SessionData.cs b/src/Intersvyaz.Core/Models/SessionData.cs
new file mode 100644
index 0000000..dadc5f4
--- /dev/null
+++ b/src/Intersvyaz.Core/Models/SessionData.cs
@@ -0,0 +1,13 @@
+using System;
+
+namespace Intersvyaz.Core.Models
+{
+    public class SessionData
+    {
+        public string Username { get; set; }
+
+        public string Token { get; set; }
+
+        public DateTime ExpiresAt { get; set; }
+    }
+}
diff --git a/src/Intersvyaz.Core/Services/ISessionService.cs b/src/Intersvyaz.Core/Services/ISessionService.cs
new file mode 100644
index 0000000..d0e369f
--- /dev/null
+++ b/src/Intersvyaz.Core/Services/ISessionService.cs
@@ -0,0 +1,33 @@
+using System.Threading.Tasks;
+using Intersvyaz.Core.Models;
+
+namespace Intersvyaz.Core.Services
+{
+    public interface ISessionService
+    {
+        /// <summary>
+        /// Получить сессию пользователя. При отсутствие сессии,
+        /// входит в систему автоматически.
+        /// </summary>
+        /// <param name="username">Имя пользователя.</param>
+        /// <param name="password">Пароль пользователя.</param>
+        /// <returns>Данные об сессии.</returns>
+        Task<SessionData> GetSessionAsync(string username, string password);
+
+        /// <summary>
+        /// Получить сессию пользователя.
+        /// </summary>
+        /// <returns>Данные об сессии.</returns>
+        SessionData GetSession();
+
+        /// <summary>
+        /// Проверить, есть ли сессия пользователя.
+        /// </summary>
+        bool HasSession();
+
+        /// <summary>
+        /// Удалить сессию пользователя.
+        /// </summary>
+        void DeleteSession();
+    }
+}