StructureMap Configuration and Object Creation

Reference: StructureMap - Scoping and Lifecycle Management
My Test version: StructureMap 2.6.1

[ Configuration for Object Creation ] [ The Code ]

Configuration for Object Creation

Recently I've used StructureMap in one of my projects and I begin to like it, especially I can control the object life cycle via StructureMap without changing my code. The followings are some ways how to configure StructureMap to create object instance.

1. Per request basis

   StructureMap by default constructs object instance transiently. Thus, each time you will get a new instance.

       public void NewPerRequest() {
   
         Container mymap = new Container(x => {
           x.For<ISimple>().Use<Simple>();
         });
   
         ISimple first = mymap.GetInstance<ISimple>();
         ISimple second = mymap.GetInstance<ISimple>();
   
         string formatter = "PerRequest [default]: instances are the same? {0}";
         System.Console.WriteLine(formatter, ReferenceEquals(first, second));
       }
   

2. Singleton

   StructureMap can inject code for you to apply Singleton design pattern if you want your object remains one and only one instance to be active during the life of the application.

       public void Singleton() {
         Container mymap = new Container(x => {
           x.For<ISimple>().Singleton().Use<Simple>();
         });
   
         ISimple first = mymap.GetInstance<ISimple>();
         ISimple second = mymap.GetInstance<ISimple>();
   
         string formatter =  "Singleton: instances are the same? {0}";
         System.Console.WriteLine(formatter, ReferenceEquals(first, second));
       }    
   

3. HttpContextScoped

   You can configure StructureMap to contruct objects to live in HttpContext scope. This method only uses in Web application.

       public void HttpContextScoped() {
         Container mymap = new Container(x => {
           x.For<ISimple>().HttpContextScoped().Use<Simple>();
         });
   
         using (new MockHttpContext()) {
           ISimple first = mymap.GetInstance<ISimple>();
           ISimple second = mymap.GetInstance<ISimple>();
   
           string formatter = "HttpContextScoped: instances are the same: {0}";
           System.Console.WriteLine(formatter, ReferenceEquals(first, second));
         }
       }
   

4. HttpContextLifecycle

   Configure StructureMap to contruct objects to live in HttpContext life cycle. This method only uses in Web application.

       public void HttpContextLifecycle() {
         Container mymap = new Container(x => {
           x.For<ISimple>().LifecycleIs(new HttpContextLifecycle()).Use<Simple>();
         });
   
         using (new MockHttpContext()) {
           ISimple first = mymap.GetInstance<ISimple>();
           ISimple second = mymap.GetInstance<ISimple>();
   
           string formatter = "HttpContextLifecycle: instances are the same: {0}";
           System.Console.WriteLine(formatter, ReferenceEquals(first, second));
         }
       }
   

5. HttpSessionLifecycle

   Configure StructureMap to instantiate an object in HttpSession context. Like the previous two methods, it only works in regular Web environment.

       public void HttpSessionLifecycle() {
         Container mymap = new Container(x => {
           x.For<ISimple>().LifecycleIs(new HttpSessionLifecycle()).Use<Simple>();
         });
   
   
         #region Create HttpSession environment for test
         // Mock a new HttpContext by using SimpleWorkerRequest
         System.Web.Hosting.SimpleWorkerRequest request =
           new System.Web.Hosting.SimpleWorkerRequest("/", string.Empty, string.Empty, string.Empty, new System.IO.StringWriter());
   
         System.Web.HttpContext.Current = new System.Web.HttpContext(request);
   
         MockHttpSession mySession = new MockHttpSession(
             Guid.NewGuid().ToString(),
             new MockSessionObjectList(),
             new System.Web.HttpStaticObjectsCollection(),
             600,
             true,
             System.Web.HttpCookieMode.AutoDetect,
             System.Web.SessionState.SessionStateMode.Custom,
             false);
   
         System.Web.SessionState.SessionStateUtility.AddHttpSessionStateToContext(
            System.Web.HttpContext.Current, mySession
         );
         #endregion
   
         // now we are ready to test
         ISimple first = mymap.GetInstance<ISimple>();
         ISimple second = mymap.GetInstance<ISimple>();
   
         string formatter = "HttpSessionLifecycle: instances are the same: {0}";
         System.Console.WriteLine(formatter, ReferenceEquals(first, second));
   
       }
   

6. HybridSessionLifecycle

   Those related to HttpContext or HttpSession are only used in ASP.NET Web environment. You won't be able to have your instance to run in client or service environment. HybridSessionLifecycle may be used to resolve it. For this method, HybridSessionLifecycle will try to use HttpContext storage if it exists; otherwise, it uses ThreadLocal storage. However, I found that this method somehow won't work with HttpHandler.

       // According to my experience, 
       // HybridSessionLifecycle works in most situations (including regular Web environment, 
       // Web service, console) but it doesn't work well with HttpHandler while 
       // HybridHttpOrThreadLocalStorage does. 
       public void HybridSessionLifecycle() {
         Container mymap = new Container(x => {
           x.For<ISimple>().LifecycleIs(new HybridSessionLifecycle()).Use<Simple>();
         });
   
   
         ISimple first = mymap.GetInstance<ISimple>();
         ISimple second = mymap.GetInstance<ISimple>();
     
         string formatter = "HttpSessionLifecycle: instances are the same: {0}";
         System.Console.WriteLine(formatter, ReferenceEquals(first, second));
       }
   

7. HybridHttpOrThreadLocalScoped

   Like HybridSessionLifecycle, it works for most situations. It also work well in a HttpHandler.

      // Unlike HybridSessionLifecycle, it works well with HttpHandlers and WCF Services 
       // besides a regular ASP.NET environment.
       public void HybridHttpOrThreadLocalScoped() {
         Container mymap = new Container(x => {        
           x.For<ISimple>().HybridHttpOrThreadLocalScoped().Use<Simple>();
         });
   
         ISimple first = mymap.GetInstance<ISimple>();
         ISimple second = mymap.GetInstance<ISimple>();
   
         string formatter = "HybridHttpOrThreadLocalScoped: instances are the same: {0}";
         System.Console.WriteLine(formatter, ReferenceEquals(first, second));
       }
   

8. UniquePerRequestLifecycle

   You can instruct StructureMap to create an unique instance per request in order to ensure no corrupted data and all states in fresh.

       public void UniquePerRequestLifecycle() {
         Container mymap = new Container(x => {
           x.For<ISimple>().LifecycleIs(new UniquePerRequestLifecycle()).Use<Simple>();
         });
   
         ISimple first = mymap.GetInstance<ISimple>();
         ISimple second = mymap.GetInstance<ISimple>();
   
         string formatter = "HttpContext Scope: instances are the same: {0}";
         System.Console.WriteLine(formatter, ReferenceEquals(first, second));
       }
   

The Code

• NUnit Test

  using System;
  using StructureMapTest.Mocks;
  using StructureMap;
  using StructureMap.Pipeline;
  using StructureMap.Configuration.DSL;
  using NUnit.Framework;
  
  namespace StructureMapTest.UnitTest {
    [TestFixture]
    public class ReferenceEqualTest {
  
      private delegate NUnit.Framework.Constraints.SameAsConstraint CompareConstraintDelegate(object expected);
  
      private void Compare<T>(string formatter, CompareConstraintDelegate sameOrNot) where T : ILifecycle {
        Container mymap = new Container(x => {
          T t = Activator.CreateInstance<T>();
          x.For<ISimple>().LifecycleIs(t).Use<Simple>();
        });
  
        Compare(mymap, formatter, sameOrNot);
      }
  
      private void Compare(Container mymap, string formatter, CompareConstraintDelegate sameOrNot) {
        ISimple first = mymap.GetInstance<ISimple>();
        ISimple second = mymap.GetInstance<ISimple>();
  
        System.Console.WriteLine(formatter, ReferenceEquals(first, second));
  
        // Simulate to 2 situations:
        // 1. Assert.That(first, Is.SameAs(second));
        // 2. Assert.That(first, Is.Not.SameAs(second));
        Assert.That(first, sameOrNot(second));
      }
  
      [Test]
      public void Different_on_per_request_basis() {
  
        Container mymap = new Container(x => {
          x.For<ISimple>().Use<Simple>();
        });
  
        Compare(mymap, "PerRequest [default]: instances are the same? {0}", Is.Not.SameAs);
      }
  
      [Test]
      public void Same_on_Singleton_instance() {
        Container mymap = new Container(x => {
          x.For<ISimple>().Singleton().Use<Simple>();
        });
  
        Compare(mymap, "Singleton: instances are the same? {0}", Is.SameAs);
      }
  
      [Test]
      public void Same_on_HttpContextScoped() {
        Container mymap = new Container(x => {
          x.For<ISimple>().HttpContextScoped().Use<Simple>();
        });
  
        using (new MockHttpContext()) {
          Compare(mymap, "HttpContextScoped: instances are the same: {0}", Is.SameAs);
        }
      }
  
      [Test]
      public void Same_on_HttpContextLifecycle() {
        Container mymap = new Container(x => {
          x.For<ISimple>().LifecycleIs(new HttpContextLifecycle()).Use<Simple>();
        });
  
        using (new MockHttpContext()) {
          Compare(mymap, "HttpContextLifecycle: instances are the same: {0}", Is.SameAs);
        }
      }
  
      [Test]
      public void Same_on_HttpSessionLifecycle() {
        Container mymap = new Container(x => {
          x.For<ISimple>().LifecycleIs(new HttpSessionLifecycle()).Use<Simple>();
        });
  
        #region Create HttpSession environment for test
        // Mock a new HttpContext by using SimpleWorkerRequest
        System.Web.Hosting.SimpleWorkerRequest request =
          new System.Web.Hosting.SimpleWorkerRequest("/", string.Empty, string.Empty, string.Empty, new System.IO.StringWriter());
  
        System.Web.HttpContext.Current = new System.Web.HttpContext(request);
  
        MockHttpSession mySession = new MockHttpSession(
            Guid.NewGuid().ToString(),
            new MockSessionObjectList(),
            new System.Web.HttpStaticObjectsCollection(),
            600,
            true,
            System.Web.HttpCookieMode.AutoDetect,
            System.Web.SessionState.SessionStateMode.Custom,
            false);
  
        System.Web.SessionState.SessionStateUtility.AddHttpSessionStateToContext(
           System.Web.HttpContext.Current, mySession
        );
        #endregion
  
        // now we are ready to test
        Compare(mymap, "HttpSessionLifecycle: instances are the same: {0}", Is.SameAs);
      }
  
      // According to my experience, 
      // HybridSessionLifecycle works in most situations (including regular Web environment, 
      // Web service, console) but it doesn't work well with HttpHandler while 
      // HybridHttpOrThreadLocalStorage does. 
      [Test]
      public void Same_on_HybridSessionLifecycle() {
        Compare<HybridSessionLifecycle>("HybridSessionLifecycle: instances are the same: {0}", Is.SameAs);
      }
  
      // Unlike HybridSessionLifecycle, it works well with HttpHandlers and WCF Services 
      // besides a regular ASP.NET environment.
      [Test]
      public void Same_on_HybridHttpOrThreadLocalScoped() {
        Container mymap = new Container(x => {
          //x.For<ISimple>().HybridHttpOrThreadLocalScoped().Use<Simple>().Named("MyInstanceName");
          x.For<ISimple>().HybridHttpOrThreadLocalScoped().Use<Simple>();
        });
        Compare(mymap, "HybridHttpOrThreadLocalScoped: instances are the same: {0}", Is.SameAs);
      }
  
      [Test]
      public void Different_on_UniquePerRequestLifecycle() {
        Compare<UniquePerRequestLifecycle>("HttpContext Scope: instances are the same: {0}", Is.Not.SameAs);
      }
  
    }
  }
  

• class Simple

  using System;
  
  namespace StructureMapTest.Mocks {
    public interface ISimple {
      void DoSomething();
    }
  
    public class Simple : ISimple {
      public void DoSomething() {
      }
    }
  }
  

• class MockHttpContext

  using System;
  
  namespace StructureMapTest.Mocks {
    public class MockHttpContext : IDisposable {
      private readonly System.IO.StringWriter sw;
  
      public MockHttpContext() {
        var httpRequest = new System.Web.HttpRequest("notExisted.aspx", "http://localhost", string.Empty);
        sw = new System.IO.StringWriter();
        var httpResponse = new System.Web.HttpResponse(sw);
        System.Web.HttpContext.Current = new System.Web.HttpContext(httpRequest, httpResponse);
      }
  
      public void Dispose() {
        sw.Dispose();
        System.Web.HttpContext.Current = null;
      }
    }
  }
  

• class MockHttpSession and class MockSessionObjectList

  using System;
  
  namespace StructureMapTest.Mocks {
    // This class follows the example at:
    // http://msdn.microsoft.com/en-us/library/system.web.sessionstate.ihttpsessionstate.aspx
    public sealed class MockHttpSession : System.Web.SessionState.IHttpSessionState {
      ...
    } 
  } 
  
  using System;
  
  namespace StructureMapTest.Mocks {
    // This class follows the example at 
    // http://msdn.microsoft.com/en-us/library/system.web.sessionstate.isessionstateitemcollection(v=VS.90).aspx
    public class MockSessionObjectList : System.Web.SessionState.ISessionStateItemCollection {
      ...
    } 
  }