Activation error occured while trying to get instance of type ICacheManager, key “Cache Manager”

问题:

I seem to have hit a wall here and would appreciate some help from anyone who is able to on this one. I am not exactly sure what the error message below means. I am using the Caching Block of Enterprise Pattern Services but I keep running in to the problem below. I downloaded the latest version and tried stepping through to the issue but I can't seem to pin the exact problem and I need help please. Thanks in advance

Test method WorldBank.Service.Business.UnitTest.TopicsManagerTest.Call_Children_out_of_schoolTest threw exception:  Microsoft.Practices.ServiceLocation.ActivationException: Activation error occured while trying to get instance of type ICacheManager, key "Cache Manager" ---> Microsoft.Practices.Unity.ResolutionFailedException: Resolution of the dependency failed, type = "Microsoft.Practices.EnterpriseLibrary.Caching.ICacheManager", name = "Cache Manager". Exception occurred while: while resolving. Exception is: InvalidOperationException - The current type, Microsoft.Practices.EnterpriseLibrary.Caching.ICacheManager, is an interface and cannot be constructed. Are you missing a type mapping? ----------------------------------------------- At the time of the exception, the container was:    Resolving Microsoft.Practices.EnterpriseLibrary.Caching.ICacheManager,WuCache  ---> System.InvalidOperationException: The current type, Microsoft.Practices.EnterpriseLibrary.Caching.ICacheManager, is an interface and cannot be constructed. Are you missing a type mapping?   Microsoft.Practices.ObjectBuilder2.DynamicMethodConstructorStrategy.ThrowForAttemptingToConstructInterface(IBuilderContext context) in e:\Builds\Unity\UnityTemp\Compile\Unity\Unity\Src\ObjectBuilder\Strategies\BuildPlan\DynamicMethod\Creation\DynamicMethodConstructorStrategy.cs: line 209 BuildUp_Microsoft.Practices.EnterpriseLibrary.Caching.ICacheManager(IBuilderContext ) Microsoft.Practices.ObjectBuilder2.DynamicMethodBuildPlan.BuildUp(IBuilderContext context) in e:\Builds\Unity\UnityTemp\Compile\Unity\Unity\Src\ObjectBuilder\Strategies\BuildPlan\DynamicMethod\DynamicMethodBuildPlan.cs: line 37 Microsoft.Practices.ObjectBuilder2.BuildPlanStrategy.PreBuildUp(IBuilderContext context) in e:\Builds\Unity\UnityTemp\Compile\Unity\Unity\Src\ObjectBuilder\Strategies\BuildPlan\BuildPlanStrategy.cs: line 43 Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) in e:\Builds\Unity\UnityTemp\Compile\Unity\Unity\Src\ObjectBuilder\Strategies\StrategyChain.cs: line 110 Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, Object existing, String name, IEnumerable`1 resolverOverrides) in e:\Builds\Unity\UnityTemp\Compile\Unity\Unity\Src\UnityContainer.cs: line 511 Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, Object existing, String name, IEnumerable`1 resolverOverrides) in e:\Builds\Unity\UnityTemp\Compile\Unity\Unity\Src\UnityContainer.cs: line 515 Microsoft.Practices.Unity.UnityContainer.Resolve(Type t, String name, ResolverOverride[] resolverOverrides) in e:\Builds\Unity\UnityTemp\Compile\Unity\Unity\Src\UnityContainer.cs: line 173 Microsoft.Practices.Unity.UnityServiceLocator.DoGetInstance(Type serviceType, String key) in e:\Builds\Unity\UnityTemp\Compile\Unity\Unity\Src\UnityServiceLocator.cs: line 64 Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key) in c:\Home\Chris\Projects\CommonServiceLocator\main\Microsoft.Practices.ServiceLocation\ServiceLocatorImplBase.cs: line 49 Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key) in c:\Home\Chris\Projects\CommonServiceLocator\main\Microsoft.Practices.ServiceLocation\ServiceLocatorImplBase.cs: line 53 Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance[TService](String key) in c:\Home\Chris\Projects\CommonServiceLocator\main\Microsoft.Practices.ServiceLocation\ServiceLocatorImplBase.cs: line 103 Microsoft.Practices.EnterpriseLibrary.Caching.CacheFactory.InnerGetCacheManager(String cacheManagerName) in e:\Builds\EntLib\Latest\Source\Blocks\Caching\Src\Caching\CacheFactory.cs: line 66 Microsoft.Practices.EnterpriseLibrary.Caching.CacheFactory.GetCacheManager(String cacheManagerName) in e:\Builds\EntLib\Latest\Source\Blocks\Caching\Src\Caching\CacheFactory.cs: line 53 WorldBank.Service.Business.ResponseManager.Get_w_Utility() in C:\SOOfficialPiece\WorldBank.Service.Business\ResponseManager.cs: line 42 WorldBank.Service.Business.ResponseManager..ctor() in C:\SOOfficialPiece\WorldBank.Service.Business\ResponseManager.cs: line 34 WorldBank.Service.Business.ResponseManager.getResponseObjectJSON(Int32 perpage, Object results, Boolean doDeepRetrieval) in C:\SOOfficialPiece\WorldBank.Service.Business\ResponseManager.cs: line 68 System.Dynamic.UpdateDelegates.UpdateAndExecute4[T0,T1,T2,T3,TRet](CallSite site, T0 arg0, T1 arg1, T2 arg2, T3 arg3) WorldBankBusiness.Topics.TopicsManager.Call_Children_out_of_school(PersonType persontype, EnrollmentType enrollmenttype, String countrycode) in C:\SOOfficialPiece\WorldBank.Service.Business\TopicsManager.cs: line 39 WorldBank.Service.Business.UnitTest.TopicsManagerTest.Call_Children_out_of_schoolTest() in C:\SOOfficialPiece\WorldBank.Service.Business.UnitTest\TopicsManagerTest.cs: line 88 

回答1:

The Caching Application Block requires some configuration information to be present in the app/web.config before it can be used (AFAIK, unfortunately it is tough to find documentation stating otherwise). Without that configuration info, the following code will cause that same exception to be thrown as you are seeing:

var cm = CacheFactory.GetCacheManager("MyCacheManager"); 

In order to get a CacheManager, you need to define the CacheManager in your app.config or web.config:

<configuration>     <configSections>         <section name="cachingConfiguration"                   type="Microsoft.Practices.EnterpriseLibrary.Caching.Configuration.CacheManagerSettings, Microsoft.Practices.EnterpriseLibrary.Caching, Version=5.0.414.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true" />     </configSections>     <cachingConfiguration defaultCacheManager="MyCacheManager">         <cacheManagers>            <add name="MyCacheManager" type="Microsoft.Practices.EnterpriseLibrary.Caching.CacheManager, Microsoft.Practices.EnterpriseLibrary.Caching, Version=5.0.414.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"                  expirationPollFrequencyInSeconds="60"                  maximumElementsInCacheBeforeScavenging="50000"                  numberToRemoveWhenScavenging="1000"                   backingStoreName="NullBackingStore" />         </cacheManagers>         <backingStores>             <add type="Microsoft.Practices.EnterpriseLibrary.Caching.BackingStoreImplementations.NullBackingStore, Microsoft.Practices.EnterpriseLibrary.Caching, Version=5.0.414.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"                   name="NullBackingStore" />         </backingStores>     </cachingConfiguration> </configuration> 

Once you add the configuration values, you should be able to get a valid CacheManager from the CacheFactory. The post also has some more information that might help you.

It is worth noting that if you are using .NET 4.0, for non web apps you can use MemoryCache (in the System.Runtime.Caching namespace) which provides similar functionality but does not require all of this configuration. And for web apps you can of course use the Cache class in System.Web.Caching.

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