diff --git a/Source/Euonia.Modularity/Dependency/ILazyServiceProvider.cs b/Source/Euonia.Modularity/Dependency/ILazyServiceProvider.cs
index 6d24b3a..8ec6a0e 100644
--- a/Source/Euonia.Modularity/Dependency/ILazyServiceProvider.cs
+++ b/Source/Euonia.Modularity/Dependency/ILazyServiceProvider.cs
@@ -5,63 +5,131 @@
 /// </summary>
 public interface ILazyServiceProvider
 {
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <typeparam name="T"></typeparam>
-    /// <returns></returns>
-    T GetRequiredService<T>();
-
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <param name="serviceType"></param>
-    /// <returns></returns>
-    object GetRequiredService(Type serviceType);
-
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <typeparam name="T"></typeparam>
-    /// <returns></returns>
-    T GetService<T>();
-
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <param name="serviceType"></param>
-    /// <returns></returns>
-    object GetService(Type serviceType);
-
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <param name="defaultValue"></param>
-    /// <typeparam name="T"></typeparam>
-    /// <returns></returns>
-    T GetService<T>(T defaultValue);
-
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <param name="serviceType"></param>
-    /// <param name="defaultValue"></param>
-    /// <returns></returns>
-    object GetService(Type serviceType, object defaultValue);
-
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <param name="serviceType"></param>
-    /// <param name="factory"></param>
-    /// <returns></returns>
-    object GetService(Type serviceType, Func<IServiceProvider, object> factory);
-
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <param name="factory"></param>
-    /// <typeparam name="T"></typeparam>
-    /// <returns></returns>
-    T GetService<T>(Func<IServiceProvider, object> factory);
+	/// <summary>
+	/// Get service of type <typeparamref name="T"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <typeparam name="T">The type of service object to get.</typeparam>
+	/// <returns></returns>
+	T GetRequiredService<T>();
+
+	/// <summary>
+	/// Get service of type <paramref name="serviceType"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <param name="serviceType"></param>
+	/// <returns></returns>
+	object GetRequiredService(Type serviceType);
+
+	/// <summary>
+	/// Get service of type <typeparamref name="T"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <typeparam name="T">The type of service object to get.</typeparam>
+	/// <returns></returns>
+	T GetService<T>();
+
+	/// <summary>
+	/// Get service of type <paramref name="serviceType"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <param name="serviceType"></param>
+	/// <returns></returns>
+	object GetService(Type serviceType);
+
+	/// <summary>
+	/// Get service of type <typeparamref name="T"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <param name="defaultValue"></param>
+	/// <typeparam name="T">The type of service object to get.</typeparam>
+	/// <returns></returns>
+	T GetService<T>(T defaultValue);
+
+	/// <summary>
+	/// 
+	/// </summary>
+	/// <param name="serviceType"></param>
+	/// <param name="defaultValue"></param>
+	/// <returns></returns>
+	object GetService(Type serviceType, object defaultValue);
+
+	/// <summary>
+	/// Get service of <paramref name="serviceType"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <param name="serviceType"></param>
+	/// <param name="factory"></param>
+	/// <returns></returns>
+	object GetService(Type serviceType, Func<IServiceProvider, object> factory);
+
+	/// <summary>
+	/// Get service of type <typeparamref name="T"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <param name="factory"></param>
+	/// <typeparam name="T">The type of service object to get.</typeparam>
+	/// <returns></returns>
+	T GetService<T>(Func<IServiceProvider, object> factory);
+
+	/// <summary>
+	/// Get service of <paramref name="serviceType"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <param name="serviceType">An object that specifies the type of service object to get.</param>
+	/// <param name="serviceKey">An object that specifies the key of service object to get.</param>
+	/// <returns></returns>
+	object GetKeyedService(Type serviceType, object serviceKey);
+
+	/// <summary>
+	/// Get service of type <typeparamref name="T"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <typeparam name="T">The type of service object to get.</typeparam>
+	/// <param name="serviceKey">An object that specifies the key of service object to get.</param>
+	/// <returns></returns>
+	T GetRequiredKeyedService<T>(object serviceKey);
+
+	/// <summary>
+	/// Get service of type <typeparamref name="T"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <typeparam name="T">The type of service object to get.</typeparam>
+	/// <param name="serviceKey">An object that specifies the key of service object to get.</param>
+	/// <returns></returns>
+	T GetKeyedService<T>(object serviceKey);
+
+	/// <summary>
+	/// Get service of type <paramref name="serviceType"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <param name="serviceType"></param>
+	/// <param name="serviceKey">An object that specifies the key of service object to get.</param>
+	/// <returns></returns>
+	object GetRequiredKeyedService(Type serviceType, object serviceKey);
+
+	/// <summary>
+	/// Get service of type <typeparamref name="T"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <typeparam name="T">The type of service object to get.</typeparam>
+	/// <param name="serviceKey">An object that specifies the key of service object to get.</param>
+	/// <param name="defaultValue"></param>
+	/// <returns></returns>
+	T GetKeyedService<T>(object serviceKey, T defaultValue);
+
+	/// <summary>
+	/// Get service of type <typeparamref name="T"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <typeparam name="T">The type of service object to get.</typeparam>
+	/// <param name="serviceKey">An object that specifies the key of service object to get.</param>
+	/// <param name="factory"></param>
+	/// <returns></returns>
+	T GetKeyedService<T>(object serviceKey, Func<IServiceProvider, T> factory);
+
+	/// <summary>
+	/// Get service of type <paramref name="serviceType"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <param name="serviceType"></param>
+	/// <param name="serviceKey">An object that specifies the key of service object to get.</param>
+	/// <param name="factory"></param>
+	/// <returns></returns>
+	object GetKeyedService(Type serviceType, object serviceKey, Func<IServiceProvider, object> factory);
+
+	/// <summary>
+	/// Get service of type <paramref name="serviceType"/> from the <see cref="IServiceProvider"/>.
+	/// </summary>
+	/// <param name="serviceType"></param>
+	/// <param name="serviceKey">An object that specifies the key of service object to get.</param>
+	/// <param name="defaultValue"></param>
+	/// <returns></returns>
+	object GetKeyedService(Type serviceType, object serviceKey, object defaultValue);
 }
\ No newline at end of file
diff --git a/Source/Euonia.Modularity/Dependency/LazyServiceProvider.Keyed.cs b/Source/Euonia.Modularity/Dependency/LazyServiceProvider.Keyed.cs
new file mode 100644
index 0000000..d1f7ee4
--- /dev/null
+++ b/Source/Euonia.Modularity/Dependency/LazyServiceProvider.Keyed.cs
@@ -0,0 +1,55 @@
+using Microsoft.Extensions.DependencyInjection;
+using Nerosoft.Euonia.Modularity;
+
+namespace System;
+
+public partial class LazyServiceProvider
+{
+	/// <inheritdoc />
+	public virtual T GetKeyedService<T>(object serviceKey)
+	{
+		return (T)GetKeyedService(typeof(T), serviceKey);
+	}
+
+	/// <inheritdoc />
+	public virtual object GetKeyedService(Type serviceType, object serviceKey)
+	{
+		return CachedServices.GetOrAdd(new ServiceIdentifier(serviceKey, serviceType), _ => new Lazy<object>(() => ServiceProvider.GetKeyedService(serviceType, serviceKey))).Value;
+	}
+
+	/// <inheritdoc />
+	public virtual T GetRequiredKeyedService<T>(object serviceKey)
+	{
+		return (T)GetRequiredKeyedService(typeof(T), serviceKey);
+	}
+
+	/// <inheritdoc />
+	public virtual object GetRequiredKeyedService(Type serviceType, object serviceKey)
+	{
+		return CachedServices.GetOrAdd(new ServiceIdentifier(serviceKey, serviceType), _ => new Lazy<object>(() => ServiceProvider.GetRequiredKeyedService(serviceType, serviceKey))).Value!;
+	}
+
+	/// <inheritdoc />
+	public virtual T GetKeyedService<T>(object serviceKey, T defaultValue)
+	{
+		return (T)GetKeyedService(typeof(T), serviceKey, defaultValue);
+	}
+
+	/// <inheritdoc />
+	public virtual T GetKeyedService<T>(object serviceKey, Func<IServiceProvider, T> factory)
+	{
+		return (T)GetKeyedService(typeof(T), serviceKey, provider => factory(provider));
+	}
+
+	/// <inheritdoc />
+	public virtual object GetKeyedService(Type serviceType, object serviceKey, Func<IServiceProvider, object> factory)
+	{
+		return CachedServices.GetOrAdd(new ServiceIdentifier(serviceKey, serviceType), _ => new Lazy<object>(() => factory(ServiceProvider))).Value;
+	}
+
+	/// <inheritdoc />
+	public virtual object GetKeyedService(Type serviceType, object serviceKey, object defaultValue)
+	{
+		return CachedServices.GetOrAdd(new ServiceIdentifier(serviceKey, serviceType), _ => new Lazy<object>(() => defaultValue)).Value;
+	}
+}
diff --git a/Source/Euonia.Modularity/Dependency/LazyServiceProvider.cs b/Source/Euonia.Modularity/Dependency/LazyServiceProvider.cs
index 4db8eb7..4252300 100644
--- a/Source/Euonia.Modularity/Dependency/LazyServiceProvider.cs
+++ b/Source/Euonia.Modularity/Dependency/LazyServiceProvider.cs
@@ -1,100 +1,102 @@
-namespace System;
+using System.Collections.Concurrent;
+using Nerosoft.Euonia.Modularity;
+
+namespace System;
 
 /// <summary>
 /// Implementation of <see cref="ILazyServiceProvider"/>.
 /// </summary>
-public class LazyServiceProvider : ILazyServiceProvider
+public partial class LazyServiceProvider : ILazyServiceProvider
 {
-    /// <summary>
-    /// 
-    /// </summary>
-    protected IDictionary<Type, object> CachedServices { get; set; }
+	/// <summary>
+	/// Gets the cached services.
+	/// </summary>
+	private ConcurrentDictionary<ServiceIdentifier, Lazy<object>> CachedServices { get; } = new();
 
-    /// <summary>
-    /// 
-    /// </summary>
-    protected IServiceProvider ServiceProvider { get; }
+	/// <summary>
+	/// Gets the service provider instance.
+	/// </summary>
+	private IServiceProvider ServiceProvider { get; }
 
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <param name="serviceProvider"></param>
-    public LazyServiceProvider(IServiceProvider serviceProvider)
-    {
-        ServiceProvider = serviceProvider;
-        CachedServices = new Dictionary<Type, object>();
-    }
+	/// <summary>
+	/// Initializes a new instance of the <see cref="LazyServiceProvider"/> class.
+	/// </summary>
+	/// <param name="serviceProvider"></param>
+	public LazyServiceProvider(IServiceProvider serviceProvider)
+	{
+		ServiceProvider = serviceProvider;
+	}
 
-    /// <inheritdoc />
-    public virtual T GetRequiredService<T>()
-    {
-        return (T)GetRequiredService(typeof(T));
-    }
+	/// <inheritdoc />
+	public virtual T GetRequiredService<T>()
+	{
+		return (T)GetRequiredService(typeof(T));
+	}
 
-    /// <summary>
-    /// 
-    /// </summary>
-    /// <param name="serviceType"></param>
-    /// <returns></returns>
-    /// <exception cref="ArgumentNullException"></exception>
-    /// <exception cref="NullReferenceException"></exception>
-    public virtual object GetRequiredService(Type serviceType)
-    {
-        return CachedServices.GetOrAdd(serviceType, () =>
-        {
-            if (ServiceProvider == null)
-            {
-                throw new ArgumentNullException(nameof(ServiceProvider));
-            }
+	/// <summary>
+	/// 
+	/// </summary>
+	/// <param name="serviceType"></param>
+	/// <returns></returns>
+	/// <exception cref="ArgumentNullException"></exception>
+	/// <exception cref="NullReferenceException"></exception>
+	public virtual object GetRequiredService(Type serviceType)
+	{
+		return CachedServices.GetOrAdd(new ServiceIdentifier(serviceType), _ => new Lazy<object>(() =>
+		{
+			if (ServiceProvider == null)
+			{
+				throw new ArgumentNullException(nameof(ServiceProvider));
+			}
 
-            if (serviceType == null)
-            {
-                throw new ArgumentNullException(nameof(serviceType));
-            }
+			if (serviceType == null)
+			{
+				throw new ArgumentNullException(nameof(serviceType));
+			}
 
-            var service = ServiceProvider.GetService(serviceType);
-            if (service == null)
-            {
-                throw new NullReferenceException(nameof(serviceType));
-            }
+			var service = ServiceProvider.GetService(serviceType);
+			if (service == null)
+			{
+				throw new NullReferenceException(nameof(serviceType));
+			}
 
-            return service;
-        });
-    }
+			return service;
+		})).Value;
+	}
 
-    /// <inheritdoc />
-    public virtual T GetService<T>()
-    {
-        return (T)GetService(typeof(T));
-    }
+	/// <inheritdoc />
+	public virtual T GetService<T>()
+	{
+		return (T)GetService(typeof(T));
+	}
 
-    /// <inheritdoc />
-    public virtual object GetService(Type serviceType)
-    {
-        return CachedServices.GetOrAdd(serviceType, () => ServiceProvider.GetService(serviceType));
-    }
+	/// <inheritdoc />
+	public virtual object GetService(Type serviceType)
+	{
+		return CachedServices.GetOrAdd(new ServiceIdentifier(serviceType), _ => new Lazy<object>(() => ServiceProvider.GetService(serviceType))).Value;
+	}
 
-    /// <inheritdoc />
-    public virtual T GetService<T>(T defaultValue)
-    {
-        return (T)GetService(typeof(T), defaultValue);
-    }
+	/// <inheritdoc />
+	public virtual T GetService<T>(T defaultValue)
+	{
+		return (T)GetService(typeof(T), defaultValue);
+	}
 
-    /// <inheritdoc />
-    public virtual object GetService(Type serviceType, object defaultValue)
-    {
-        return GetService(serviceType) ?? defaultValue;
-    }
+	/// <inheritdoc />
+	public virtual object GetService(Type serviceType, object defaultValue)
+	{
+		return GetService(serviceType) ?? defaultValue;
+	}
 
-    /// <inheritdoc />
-    public virtual T GetService<T>(Func<IServiceProvider, object> factory)
-    {
-        return (T)GetService(typeof(T), factory);
-    }
+	/// <inheritdoc />
+	public virtual T GetService<T>(Func<IServiceProvider, object> factory)
+	{
+		return (T)GetService(typeof(T), factory);
+	}
 
-    /// <inheritdoc />
-    public virtual object GetService(Type serviceType, Func<IServiceProvider, object> factory)
-    {
-        return CachedServices.GetOrAdd(serviceType, () => factory(ServiceProvider));
-    }
+	/// <inheritdoc />
+	public virtual object GetService(Type serviceType, Func<IServiceProvider, object> factory)
+	{
+		return CachedServices.GetOrAdd(new ServiceIdentifier(serviceType), _ => new Lazy<object>(() => factory(ServiceProvider))).Value;
+	}
 }
\ No newline at end of file
diff --git a/Source/Euonia.Modularity/Dependency/ServiceIdentifier.cs b/Source/Euonia.Modularity/Dependency/ServiceIdentifier.cs
new file mode 100644
index 0000000..bcb47b9
--- /dev/null
+++ b/Source/Euonia.Modularity/Dependency/ServiceIdentifier.cs
@@ -0,0 +1,49 @@
+namespace Nerosoft.Euonia.Modularity;
+
+internal readonly struct ServiceIdentifier : IEquatable<ServiceIdentifier>
+{
+	public object ServiceKey { get; }
+
+	public Type ServiceType { get; }
+
+	public ServiceIdentifier(Type serviceType)
+	{
+		ServiceType = serviceType;
+	}
+
+	public ServiceIdentifier(object serviceKey, Type serviceType)
+	{
+		ServiceKey = serviceKey;
+		ServiceType = serviceType;
+	}
+
+	public bool Equals(ServiceIdentifier other)
+	{
+		if (ServiceKey == null && other.ServiceKey == null)
+		{
+			return ServiceType == other.ServiceType;
+		}
+		else if (ServiceKey != null && other.ServiceKey != null)
+		{
+			return ServiceType == other.ServiceType && ServiceKey.Equals(other.ServiceKey);
+		}
+		return false;
+	}
+
+	public override bool Equals(object obj)
+	{
+		return obj is ServiceIdentifier && Equals((ServiceIdentifier)obj);
+	}
+
+	public override int GetHashCode()
+	{
+		if (ServiceKey == null)
+		{
+			return ServiceType.GetHashCode();
+		}
+		unchecked
+		{
+			return (ServiceType.GetHashCode() * 397) ^ ServiceKey.GetHashCode();
+		}
+	}
+}
diff --git a/Source/Euonia.Modularity/Extensions/ServiceProviderExtensions.cs b/Source/Euonia.Modularity/Extensions/ServiceProviderExtensions.cs
index 0533c88..aad1fed 100644
--- a/Source/Euonia.Modularity/Extensions/ServiceProviderExtensions.cs
+++ b/Source/Euonia.Modularity/Extensions/ServiceProviderExtensions.cs
@@ -1,4 +1,6 @@
-namespace System;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace System;
 
 /// <summary>
 /// The extension methods for <see cref="IServiceProvider"/> interface.
@@ -33,4 +35,22 @@ public static TService GetNamedRequiredService<TService>(this IServiceProvider p
         var @delegate = (NamedService<TService>)provider.GetService(typeof(NamedService<TService>));
         return @delegate?.Invoke(name) ?? throw new InvalidOperationException($"The service {typeof(TService).FullName} with name {name} was not found.");
     }
+
+	/// <summary>
+	/// Gets the service object of the specified type.
+	/// </summary>
+	/// <param name="provider"></param>
+	/// <param name="serviceType">An object that specifies the type of service object to get.</param>
+	/// <param name="serviceKey">An object that specifies the key of service object to get.</param>
+	/// <returns></returns>
+	/// <exception cref="InvalidOperationException"></exception>
+	public static object GetKeyedService(this IServiceProvider provider, Type serviceType, object serviceKey)
+	{
+		if (provider is IKeyedServiceProvider keyedServiceProvider)
+		{
+			return keyedServiceProvider.GetKeyedService(serviceType, serviceKey);
+		}
+
+		throw new InvalidOperationException("This service provider doesn't support keyed services.");
+	}
 }