"The type LogWriter cannot be constructed" in web app in new AppDomain

StackOverflow https://stackoverflow.com/questions/17218870

Question

I'm trying to use the Microsoft Enterprise Library 5.0 Logging Application Block in a web application. I can write to the log from the main application, but when I attempt this from a second AppDomain, any attempt to log throws an exception (shown below).

The exact same code, in a console application, works ok. I have narrowed it down to the following test code (just need to change the assembly and type name constants to match your project):

public class LogTester
{
    public const string LogWriterAssembly = "LogTest";
    public const string LogWriterType = "LogTest.LogWriter";

    public static void DoLogTest()
    {
        LogWriter localLogger = new LogWriter();
        localLogger.Log("In first AppDomain");

        AppDomain domain = GetAppDomain();

        LogWriter remoteLogger = (LogWriter)domain.CreateInstanceAndUnwrap(LogWriterAssembly, LogWriterType);
        remoteLogger.Log("In second AppDomain");
    }

    private static AppDomain GetAppDomain()
    {
        string baseFolder = AppDomain.CurrentDomain.BaseDirectory;

        string folder = AppDomain.CurrentDomain.SetupInformation.PrivateBinPath;

        if (String.IsNullOrEmpty(folder))
            folder = baseFolder;

        AppDomainSetup setup = new AppDomainSetup();
        setup.ApplicationName = "TestAppName";
        setup.ApplicationBase = baseFolder;
        setup.PrivateBinPath = folder;
        setup.ShadowCopyFiles = "true";

        return AppDomain.CreateDomain("TestAppName", null, setup);
    }
}

public class LogWriter : MarshalByRefObject
{
    public void Log(string message)
    {
        Logger.Write(AppDomain.CurrentDomain.FriendlyName + ": " + message);
    }
}

The logging configuration I'm using is just the default (created by the Enterprise Library Configuration Utility):

<configSections>
    <section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true" />
</configSections>
<loggingConfiguration name="" tracingEnabled="true" defaultCategory="General">
    <listeners>
        <add name="Event Log Listener" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FormattedEventLogTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
            listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FormattedEventLogTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
            source="Enterprise Library Logging" formatter="Text Formatter"
            log="" machineName="." traceOutputOptions="None" />
    </listeners>
    <formatters>
        <add type="Microsoft.Practices.EnterpriseLibrary.Logging.Formatters.TextFormatter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
            template="Timestamp: {timestamp}{newline}&#xA;Message: {message}{newline}&#xA;Category: {category}{newline}&#xA;Priority: {priority}{newline}&#xA;EventId: {eventid}{newline}&#xA;Severity: {severity}{newline}&#xA;Title:{title}{newline}&#xA;Machine: {localMachine}{newline}&#xA;App Domain: {localAppDomain}{newline}&#xA;ProcessId: {localProcessId}{newline}&#xA;Process Name: {localProcessName}{newline}&#xA;Thread Name: {threadName}{newline}&#xA;Win32 ThreadId:{win32ThreadId}{newline}&#xA;Extended Properties: {dictionary({key} - {value}{newline})}"
            name="Text Formatter" />
    </formatters>
    <categorySources>
        <add switchValue="All" name="General">
            <listeners>
                <add name="Event Log Listener" />
            </listeners>
        </add>
    </categorySources>
    <specialSources>
        <allEvents switchValue="All" name="All Events" />
        <notProcessed switchValue="All" name="Unprocessed Category" />
        <errors switchValue="All" name="Logging Errors &amp; Warnings">
            <listeners>
                <add name="Event Log Listener" />
            </listeners>
        </errors>
    </specialSources>
</loggingConfiguration>

In a console app, all works fine, both log messages are written. In a web app, however, I get the following exception when trying to write the second message:

[InvalidOperationException: The type LogWriter cannot be constructed. You must configure the container to supply this value.]

[ResolutionFailedException: Resolution of the dependency failed, type = "Microsoft.Practices.EnterpriseLibrary.Logging.LogWriter", name = "(none)".
Exception occurred while: while resolving.
Exception is: InvalidOperationException - The type LogWriter cannot be constructed. You must configure the container to supply this value.
-----------------------------------------------
At the time of the exception, the container was:

  Resolving Microsoft.Practices.EnterpriseLibrary.Logging.LogWriter,(none)
]

[ActivationException: Activation error occured while trying to get instance of type LogWriter, key ""]
   System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) +10582079
   System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) +336
   MvcApplication1.Controllers.LogWriter.Log(String message) in c:\dev\Sage Data Cloud\Development\MvcApplication1\MvcApplication1\Controllers\DefaultController.cs:65
   MvcApplication1.Controllers.LogTester.DoLogTest() in c:\dev\Sage Data Cloud\Development\MvcApplication1\MvcApplication1\Controllers\DefaultController.cs:38
   MvcApplication1.Controllers.DefaultController.Index() in c:\dev\Sage Data Cloud\Development\MvcApplication1\MvcApplication1\Controllers\DefaultController.cs:18
   lambda_method(Closure , ControllerBase , Object[] ) +101
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +59
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +435
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +60
   System.Web.Mvc.Async.AsyncControllerActionInvoker.InvokeSynchronousActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +50
   System.Web.Mvc.Async.<>c__DisplayClass42.<BeginInvokeSynchronousActionMethod>b__41() +75
   System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +44
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +139
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +102
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +49
   System.Web.Mvc.Async.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33() +126
   System.Web.Mvc.Async.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49() +323
   System.Web.Mvc.Async.<>c__DisplayClass37.<BeginInvokeActionMethodWithFilters>b__36(IAsyncResult asyncResult) +44
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +139
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +102
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +50
   System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +68
   System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +184
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +136
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +56
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +40
   System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +40
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +151
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +44
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +151
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +39
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +39
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +45
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +151
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +40
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9629708
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

I have references to the required Enterprise Library assemblies, so the Logging, ServiceLocation, Unity and Unity.Configuration assemblies are copied locally.

I've tried debugging into the Enterprise Library code using .NET Reflector, but the object creation is all done using dynamically generated code which I can't step into (and I don't want to get into trying to reverse engineer that from the uncommented decompiled source!).

Just wondering if anyone has come across this issue before, and possible solutions? Can't find this same issue anywhere else.

Thanks in advance. Pete

Was it helpful?

Solution

You need to set the new AppDomain's configuration file so that Enterprise Library can be configured in the new AppDomain. You can do this using the AppDomainSetup.ConfigurationFile property:

AppDomainSetup setup = new AppDomainSetup();
setup.ApplicationName = "TestAppName";
setup.ApplicationBase = baseFolder;
setup.PrivateBinPath = folder;
setup.ShadowCopyFiles = "true";
setup.ConfigurationFile = 
    AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;
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