diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/IRepository.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/IRepository.cs
new file mode 100644
index 0000000..cffe1de
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/IRepository.cs
@@ -0,0 +1,17 @@
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Interfaces
+{
+    public interface IRepository
+    {
+        UserList GetUsers();
+        User GetUser(int id);
+        TimeLogList GetTimeLogs(int userId);
+        TimeLogList GetTimeLogs(int userId, int calendarWeek);
+        IdentifierList GetUnassignedList();
+        OperationResponse UpdateUser(User user);
+        OperationResponse LogEventTime(Identifier identifier);
+    }
+}
diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/Identifier.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/Identifier.cs
new file mode 100644
index 0000000..1c3b7a6
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/Identifier.cs
@@ -0,0 +1,9 @@
+namespace Interfaces
+{
+    public class Identifier
+    {
+        public int Id { get; set; }
+        public string UniqueId { get; set; }
+        public bool IsAssociatedToUser { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/IdentifierList.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/IdentifierList.cs
new file mode 100644
index 0000000..a39fa96
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/IdentifierList.cs
@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+
+namespace Interfaces
+{
+    public class IdentifierList
+    {
+        public IdentifierList()
+        {
+            data = new List<Identifier>();
+        }
+        public List<Identifier> data { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/Interfaces.csproj b/DataCenter_Windows/WindowsDataCenter/Interfaces/Interfaces.csproj
new file mode 100644
index 0000000..6d1a25d
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/Interfaces.csproj
@@ -0,0 +1,61 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{B7347B72-E208-423A-9D99-723B558EA3D7}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>Interfaces</RootNamespace>
+    <AssemblyName>Interfaces</AssemblyName>
+    <TargetFrameworkVersion>v4.5.2</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Xml.Linq" />
+    <Reference Include="System.Data.DataSetExtensions" />
+    <Reference Include="Microsoft.CSharp" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Net.Http" />
+    <Reference Include="System.Xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="IRepository.cs" />
+    <Compile Include="Identifier.cs" />
+    <Compile Include="IdentifierList.cs" />
+    <Compile Include="OperationResponse.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="TimeLog.cs" />
+    <Compile Include="TimeLogList.cs" />
+    <Compile Include="User.cs" />
+    <Compile Include="UserList.cs" />
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
+       Other similar extension points exist, see Microsoft.Common.targets.
+  <Target Name="BeforeBuild">
+  </Target>
+  <Target Name="AfterBuild">
+  </Target>
+  -->
+</Project>
\ No newline at end of file
diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/OperationResponse.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/OperationResponse.cs
new file mode 100644
index 0000000..3851a5c
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/OperationResponse.cs
@@ -0,0 +1,12 @@
+namespace Interfaces
+{
+    public enum OperationResponse
+    {
+        NONE = 0,
+        SUCCESS = 1,
+        CREATED = 2,
+        UPDATED = 3,
+        DELETED = 4,
+        FAILED = 5
+    }
+}
\ No newline at end of file
diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/Properties/AssemblyInfo.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/Properties/AssemblyInfo.cs
new file mode 100644
index 0000000..1cf91d9
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/Properties/AssemblyInfo.cs
@@ -0,0 +1,36 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+// General Information about an assembly is controlled through the following 
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("Interfaces")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("Interfaces")]
+[assembly: AssemblyCopyright("Copyright ©  2017")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// Setting ComVisible to false makes the types in this assembly not visible 
+// to COM components.  If you need to access a type in this assembly from 
+// COM, set the ComVisible attribute to true on that type.
+[assembly: ComVisible(false)]
+
+// The following GUID is for the ID of the typelib if this project is exposed to COM
+[assembly: Guid("b7347b72-e208-423a-9d99-723b558ea3d7")]
+
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version 
+//      Build Number
+//      Revision
+//
+// You can specify all the values or you can default the Build and Revision Numbers 
+// by using the '*' as shown below:
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]
diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/TimeLog.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/TimeLog.cs
new file mode 100644
index 0000000..e144834
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/TimeLog.cs
@@ -0,0 +1,11 @@
+using System;
+
+namespace Interfaces
+{
+    public class TimeLog
+    {
+        public DateTimeOffset EventTime { get; set; }
+        public int UserId { get; set; }
+        public bool Direction { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/TimeLogList.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/TimeLogList.cs
new file mode 100644
index 0000000..cb7e9f5
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/TimeLogList.cs
@@ -0,0 +1,10 @@
+using System.Collections.Generic;
+
+namespace Interfaces
+{
+    public class TimeLogList
+    {
+        public int CalendarWeek { get; set; }
+        public List<TimeLog> TimeLogs { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/User.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/User.cs
new file mode 100644
index 0000000..e232428
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/User.cs
@@ -0,0 +1,18 @@
+using System.Collections.Generic;
+
+namespace Interfaces
+{
+    public class User
+    {
+        public User()
+        {
+            AssociatedIdentifiers = new List<Identifier>();
+        }
+        public int UserId { get; set; }
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public int HoursPerWeek { get; set; }
+        public int AssociatedIdentifierCount { get; set; }
+        public List<Identifier> AssociatedIdentifiers { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/UserList.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/UserList.cs
new file mode 100644
index 0000000..18e57ee
--- /dev/null
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/UserList.cs
@@ -0,0 +1,12 @@
+using System.Collections.Generic;
+
+namespace Interfaces
+{
+    public class UserList
+    {
+        public int UserCount { get; set; }
+        public List<User> Users { get; set; }
+        public int PageSize { get; set; }
+        public int PageNumber { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/DataCenter_Windows/WindowsDataCenter/WindowsDataCenter.sln b/DataCenter_Windows/WindowsDataCenter/WindowsDataCenter.sln
index 131620a..9d51054 100644
--- a/DataCenter_Windows/WindowsDataCenter/WindowsDataCenter.sln
+++ b/DataCenter_Windows/WindowsDataCenter/WindowsDataCenter.sln
@@ -7,6 +7,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "WindowsDataCenter", "Window
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "WindowsDataServiceHost", "WindowsDataServiceHost\WindowsDataServiceHost.csproj", "{5A4E2CF2-FA51-413E-82C7-14A19A50766D}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Interfaces", "Interfaces\Interfaces.csproj", "{B7347B72-E208-423A-9D99-723B558EA3D7}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -21,6 +23,10 @@ Global
 		{5A4E2CF2-FA51-413E-82C7-14A19A50766D}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{5A4E2CF2-FA51-413E-82C7-14A19A50766D}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{5A4E2CF2-FA51-413E-82C7-14A19A50766D}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B7347B72-E208-423A-9D99-723B558EA3D7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B7347B72-E208-423A-9D99-723B558EA3D7}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B7347B72-E208-423A-9D99-723B558EA3D7}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B7347B72-E208-423A-9D99-723B558EA3D7}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE