在appdomain中加载程序集

Question

I'm currently building a plugin framework for asp.net mvc. All plugins are copied to a directory and now I try to load them. At first I added them all to the current appdomain but that gives conflicts when there are different versions of assemblies. Therefor I was thinking to build a appdomain per plugin. Standard dll's are loaded in the code below, but the custom class that I added to test loading of different versions is not loaded. This is the code I use.

        foreach (var directoryInfo in TempPluginFolder.GetDirectories())
        {
            //AppDomainFactory fact = new AppDomainFactory();

            AppDomainSetup setup = new AppDomainSetup();
            setup.ShadowCopyFiles = "true";
            setup.LoaderOptimization = LoaderOptimization.MultiDomain;
            setup.PrivateBinPath = directoryInfo.FullName + ";" + AppDomain.CurrentDomain.SetupInformation.PrivateBinPath;

            AppDomain domain = AppDomain.CreateDomain(directoryInfo.FullName, AppDomain.CurrentDomain.Evidence,setup);

            foreach (var fileInfo in directoryInfo.GetFiles("*.dll", SearchOption.AllDirectories))
            {
                var assemblyName = AssemblyName.GetAssemblyName(fileInfo.FullName);
                domain.Load(assemblyName);
            }
            appDomains.Add(domain);
        }

For some reason my custom class that I builded is not loaded. This is the exception that I get:

Could not load file or assembly 'ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.IO.FileNotFoundException: Could not load file or assembly 'ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.

Source Error: 


Line 112:                {
Line 113:                    var assemblyName = AssemblyName.GetAssemblyName(fileInfo.FullName);
Line 114:                    domain.Load(assemblyName);
Line 115:                }
Line 116:                foreach (var fileInfo in directoryInfo.GetFiles("*.dll", SearchOption.AllDirectories))

Source File: c:\Users\Patrick\Documents\Visual Studio 2013\Projects\Project\Project.UI.Web.PluginManager\PreApplicationInit.cs    Line: 114 

Assembly Load Trace: The following information can be helpful to determine why the assembly 'ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' could not be loaded.


=== Pre-bind state information ===
LOG: DisplayName = ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
(Fully-specified)
LOG: Appbase = file:///c:/users/patrick/documents/visual studio 2013/Projects/Project/Project.UI.Web.MVC/
LOG: Initial PrivatePath = c:\users\patrick\documents\visual studio 2013\Projects\Project\Project.UI.Web.MVC\bin
Calling assembly : (Unknown).
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: c:\users\patrick\documents\visual studio 2013\Projects\Project\Project.UI.Web.MVC\web.config
LOG: Using host configuration file: C:\Users\Patrick\Documents\IISExpress\config\aspnet.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Attempting download of new URL file:///C:/Users/Patrick/AppData/Local/Temp/Temporary ASP.NET Files/root/8aa98896/e1fa08af/ClassLibrary1.DLL.
LOG: Attempting download of new URL file:///C:/Users/Patrick/AppData/Local/Temp/Temporary ASP.NET Files/root/8aa98896/e1fa08af/ClassLibrary1/ClassLibrary1.DLL.
LOG: Attempting download of new URL file:///c:/users/patrick/documents/visual studio 2013/Projects/Project/Project.UI.Web.MVC/bin/ClassLibrary1.DLL.
LOG: Attempting download of new URL file:///c:/users/patrick/documents/visual studio 2013/Projects/Project/Project.UI.Web.MVC/bin/ClassLibrary1/ClassLibrary1.DLL.
LOG: Attempting download of new URL file:///C:/Users/Patrick/AppData/Local/Temp/Temporary ASP.NET Files/root/8aa98896/e1fa08af/ClassLibrary1.EXE.
LOG: Attempting download of new URL file:///C:/Users/Patrick/AppData/Local/Temp/Temporary ASP.NET Files/root/8aa98896/e1fa08af/ClassLibrary1/ClassLibrary1.EXE.
LOG: Attempting download of new URL file:///c:/users/patrick/documents/visual studio 2013/Projects/Project/Project.UI.Web.MVC/bin/ClassLibrary1.EXE.
LOG: Attempting download of new URL file:///c:/users/patrick/documents/visual studio 2013/Projects/Project/Project.UI.Web.MVC/bin/ClassLibrary1/ClassLibrary1.EXE.

Stack Trace: 


[FileNotFoundException: Could not load file or assembly 'ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.]
System.AppDomain.Load(AssemblyName assemblyRef) +0
Project.UI.Web.PluginManager.PreApplicationInit.LoadAssemblies() in c:\Users\Patrick\Documents\Visual Studio 2013\Projects\Project\Project.UI.Web.PluginManager\PreApplicationInit.cs:114
Project.UI.Web.PluginManager.PreApplicationInit.InitializePlugins() in c:\Users\Patrick\Documents\Visual Studio 2013\Projects\Project\Project.UI.Web.PluginManager\PreApplicationInit.cs:56

[InvalidOperationException: The pre-application start initialization method InitializePlugins on type Project.UI.Web.PluginManager.PreApplicationInit threw an exception with the following error message: Could not load file or assembly 'ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified..]
System.Web.Compilation.BuildManager.InvokePreStartInitMethodsCore(ICollection`1 methods, Func`1 setHostingEnvironmentCultures) +556
System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1 methods) +132
System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded) +102
System.Web.Compilation.BuildManager.ExecutePreAppStart() +153
System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +516

[HttpException (0x80004005): The pre-application start initialization method InitializePlugins on type Project.UI.Web.PluginManager.PreApplicationInit threw an exception with the following error message: Could not load file or assembly 'ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified..]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9885060
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +101
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +254

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34009

Answer 1

As you might have notice in your debug trace, the runtime is trying to read your dll from several directories. It appears that none of them contains the specified Assembly.

Your are using "SearchOption.AllDirectories" so your assembly might come from subdirectory such as "plugin/plugin1" or "extensions/plugin1". In that case you should add this directory to your domain PrivateBinPath http://msdn.microsoft.com/en-us/library/system.appdomainsetup.privatebinpath(v=vs.110).aspx . In your example your are only adding the