Refactored.

src/AbpDesk/AbpDesk.ConsoleDemo/AbpDesk/ConsoleDemo/Program.cs

@@ -23,25 +23,20 @@ namespace AbpDesk.ConsoleDemo
 
         private static void RunDemo()
         {
-            var services = new ServiceCollection();
+            using (var application = AbpApplicationFactory.Create<AbpDeskConsoleDemoModule>(options =>
-
-            using (var application = services.AddApplication<AbpDeskConsoleDemoModule>(options =>
             {
                 options.UseAutofac();
                 AddPlugIns(options);
             }))
             {
-                using (var scope = services.BuildServiceProviderFromFactory().CreateScope())
+                application.Initialize();
-                {
-                    application.Initialize(scope.ServiceProvider);
 
-                    RunListers(application);
+                RunListers(application);
 
-                    Console.WriteLine("Press ENTER to exit...");
+                Console.WriteLine("Press ENTER to exit...");
-                    Console.ReadLine();
+                Console.ReadLine();
 
-                    application.Shutdown();
+                application.Shutdown();
-                }
             }
         }
 

src/Volo.Abp/Volo/Abp/AbpApplicationBase.cs

@@ -13,6 +13,8 @@ namespace Volo.Abp
 
         public IServiceProvider ServiceProvider { get; protected set; }
 
+        public IServiceCollection Services { get; }
+
         [NotNull]
         public AbpModuleDescriptor[] Modules { get; }
 
@@ -25,6 +27,7 @@ namespace Volo.Abp
             Check.NotNull(services, nameof(services));
 
             StartupModuleType = startupModuleType;
+            Services = services;
 
             var options = new AbpApplicationCreationOptions(services);
             optionsAction?.Invoke(options);

src/Volo.Abp/Volo/Abp/AbpApplicationFactory.cs

@@ -7,32 +7,36 @@ namespace Volo.Abp
 {
     public static class AbpApplicationFactory
     {
-        public static IAbpApplicationWithExternalServiceProvider Create<TStartupModule>(
+        // IAbpApplicationWithExternalServiceProvider //////////////////////////////////////
-            [NotNull] IServiceCollection services)
+
+        public static IAbpApplicationWithInternalServiceProvider Create<TStartupModule>(
+            [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
             where TStartupModule : IAbpModule
         {
-            return Create<TStartupModule>(services, null);
+            return Create(typeof(TStartupModule), optionsAction);
         }
 
-        public static IAbpApplicationWithExternalServiceProvider Create<TStartupModule>(
+        public static IAbpApplicationWithInternalServiceProvider Create(
-            [NotNull] IServiceCollection services,
+            [NotNull] Type startupModuleType,
-            [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction)
+            [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
-            where TStartupModule : IAbpModule
         {
-            return new AbpApplicationWithExternalServiceProvider(typeof(TStartupModule), services, optionsAction);
+            return new AbpApplicationWithInternalServiceProvider(startupModuleType, optionsAction);
         }
 
-        public static IAbpApplicationWithExternalServiceProvider Create(
+        // IAbpApplicationWithExternalServiceProvider //////////////////////////////////////
-            [NotNull] Type startupModuleType,
+
-            [NotNull] IServiceCollection services)
+        public static IAbpApplicationWithExternalServiceProvider Create<TStartupModule>(
+            [NotNull] IServiceCollection services,
+            [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
+            where TStartupModule : IAbpModule
         {
-            return Create(startupModuleType, services, null);
+            return Create(typeof(TStartupModule), services, optionsAction);
         }
 
         public static IAbpApplicationWithExternalServiceProvider Create(
             [NotNull] Type startupModuleType,
             [NotNull] IServiceCollection services,
-            [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction)
+            [CanBeNull] Action<AbpApplicationCreationOptions> optionsAction = null)
         {
             return new AbpApplicationWithExternalServiceProvider(startupModuleType, services, optionsAction);
         }

src/Volo.Abp/Volo/Abp/AbpApplicationWithInternalServiceProvider.cs

@@ -7,7 +7,7 @@ namespace Volo.Abp
 {
     internal class AbpApplicationWithInternalServiceProvider : AbpApplicationBase, IAbpApplicationWithInternalServiceProvider
     {
-        public IServiceScope ServiceScope { get; }
+        public IServiceScope ServiceScope { get; private set; }
 
         public AbpApplicationWithInternalServiceProvider(
             [NotNull] Type startupModuleType,
@@ -29,14 +29,13 @@ namespace Volo.Abp
                 services, 
                 optionsAction)
         {
-            services.AddSingleton<IAbpApplicationWithInternalServiceProvider>(_ => this);
+            Services.AddSingleton<IAbpApplicationWithInternalServiceProvider>(_ => this);
-
-            ServiceScope = services.BuildServiceProviderFromFactory().CreateScope();
-            ServiceProvider = ServiceScope.ServiceProvider;
         }
 
         public void Initialize()
         {
+            ServiceScope = Services.BuildServiceProviderFromFactory().CreateScope();
+            ServiceProvider = ServiceScope.ServiceProvider;
             ServiceProvider
                 .GetRequiredService<IModuleManager>()
                 .InitializeModules(new ApplicationInitializationContext(ServiceProvider));

src/Volo.Abp/Volo/Abp/IAbpApplication.cs

@@ -1,16 +1,36 @@
 using System;
+using Microsoft.Extensions.DependencyInjection;
 using Volo.Abp.Modularity;
 
 namespace Volo.Abp
 {
     public interface IAbpApplication : IDisposable
     {
+        /// <summary>
+        /// Type of the startup (entrance) module of the application.
+        /// </summary>
         Type StartupModuleType { get; }
 
+        /// <summary>
+        /// List of services registered to this application.
+        /// Can not add new services to this collection after application initialize.
+        /// </summary>
+        IServiceCollection Services { get; }
+
+        /// <summary>
+        /// Reference to the root service provider used by the application.
+        /// This can not be used before initialize the application.
+        /// </summary>
         IServiceProvider ServiceProvider { get; }
 
+        /// <summary>
+        /// List of modules loaded into this application.
+        /// </summary>
         AbpModuleDescriptor[] Modules { get; }
 
+        /// <summary>
+        /// Used to gracefully shutdown the application and all modules.
+        /// </summary>
         void Shutdown();
     }
 }

test/Volo.Abp.Tests/Volo/Abp/AbpApplication_Initialize_Tests.cs

@@ -11,54 +11,45 @@ namespace Volo.Abp
         [Fact]
         public void Should_Initialize_Single_Module()
         {
-            //Arrange
+            using (var application = AbpApplicationFactory.Create<IndependentEmptyModule>())
-            var services = new ServiceCollection();
-            using (var application = services.AddApplication<IndependentEmptyModule>())
             {
                 //Assert
-                var module = services.GetSingletonInstance<IndependentEmptyModule>();
+                var module = application.Services.GetSingletonInstance<IndependentEmptyModule>();
                 module.PreConfigureServicesIsCalled.ShouldBeTrue();
                 module.ConfigureServicesIsCalled.ShouldBeTrue();
                 module.PostConfigureServicesIsCalled.ShouldBeTrue();
 
-                using (var scope = services.BuildServiceProvider().CreateScope())
+                //Act
-                {
+                application.Initialize();
-                    //Act
-                    application.Initialize(scope.ServiceProvider);
 
-                    //Assert
+                //Assert
-                    application.ServiceProvider.GetRequiredService<IndependentEmptyModule>().ShouldBeSameAs(module);
+                application.ServiceProvider.GetRequiredService<IndependentEmptyModule>().ShouldBeSameAs(module);
-                    module.OnApplicationInitializeIsCalled.ShouldBeTrue();
+                module.OnApplicationInitializeIsCalled.ShouldBeTrue();
 
-                    //Act
+                //Act
-                    application.Shutdown();
+                application.Shutdown();
 
-                    //Assert
+                //Assert
-                    module.OnApplicationShutdownIsCalled.ShouldBeTrue();
+                module.OnApplicationShutdownIsCalled.ShouldBeTrue();
-                }
             }
         }
 
         [Fact]
         public void Should_Initialize_PlugIn()
         {
-            //Arrange
+            using (var application = AbpApplicationFactory.Create<IndependentEmptyModule>(options =>
-            var services = new ServiceCollection();
-
-            //Act
-            using (var application = services.AddApplication<IndependentEmptyModule>(options =>
             {
                 options.PlugInSources.AddTypes(typeof(IndependentEmptyPlugInModule));
             }))
             {
                 //Assert
-                var plugInModule = services.GetSingletonInstance<IndependentEmptyPlugInModule>();
+                var plugInModule = application.Services.GetSingletonInstance<IndependentEmptyPlugInModule>();
                 plugInModule.PreConfigureServicesIsCalled.ShouldBeTrue();
                 plugInModule.ConfigureServicesIsCalled.ShouldBeTrue();
                 plugInModule.PostConfigureServicesIsCalled.ShouldBeTrue();
 
                 //Act
-                application.Initialize(services.BuildServiceProvider());
+                application.Initialize();
 
                 //Assert
                 application.ServiceProvider.GetRequiredService<IndependentEmptyPlugInModule>().ShouldBeSameAs(plugInModule);