Adding dll reference to asp.net mvc application without restarting application

Question

I'm trying to add new dlls to my application. I've tried using Ninject:

var standardKernel = new StandardKernel();
ServiceLocator.SetLocatorProvider(() => new NinjectServiceLocator(standardKernel));
standardKernel.Load<MyPluginBootstrapper>();
standardKernel.Bind<IHelloWorldService>().To<HelloWorldService>();
DependencyResolver.SetResolver(new MyDependencyResolver(standardKernel));

I've tried using:

var _fullPluginPath = Path.Combine(path, "App2.Plugin.dll");
AppDomain.CurrentDomain.Load(Assembly.LoadFrom(_fullPluginPath).GetName());

And I always got the same error when I try to access to a controller that is in that new dll:

Compilation Error
Compiler Error Message: CS0246: The type or namespace name 'App2' could not be found (are     you missing a using directive or an assembly reference?)
Line 26:     using System.Web.Optimization;
Line 27:     using System.Web.Routing;
Line 28:     using App2.Plugin;
Line 29:     
Line 30:     

Source File: c:\Users\wilhem\AppData\Local\Temp\Temporary ASP.NET Files\root\0c41d57d\e08d7bc3\App_Web_index.cshtml.244a139d.hzhandta.0.cs    Line: 28

I'm implementing like a plugins based architecture and I want the ability to add new dlls without restart the application. Any idea with the code above?

rodrigogq · Accepted Answer · 2014-12-23 15:19:41Z

3

You can load assemblies on the go. But do not put it inside your application /bin directory. Put it on another location, like /plugins. Do not let it be public visible.

Create a public interface in which is previously know, with functions like IMyInterface.DoStuff() and return an string, whatever.

Then you can use reflection to call it:

Assembly assembly = Assembly.LoadFrom(Server.MapPath("~/plugins/myDll.dll"));
Type type = assembly.GetType("MyClass");
object instanceOfMyType = Activator.CreateInstance(type);

Make sure your MyClass implements your commom IMyInterface. You won't be able to see your classes like:

MyClass obj = new MyClass();

This would reset your ASP.NET application. But with reflection, you will be able to do something like:

string myReturn = ((IMyInterface)instanceOfMyType).DoStuff();

answered Dec 23, 2014 at 15:19

rodrigogq

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5 Comments

willver Over a year ago

My dll is a asp.net mvc application that has controllers inside. I'm building the controller factory and registering all that stuff. I can achieve this using BuildManager.AddReferencedAssembly(MyDll) but this method can be used only in PreApplicationStartMethod, even y try to use Ninject and I got the same error. I don't want call any method directly, I just want to reference my dll to my mvc main application.

rodrigogq Over a year ago

Is there a major reason for not restarting the MVC application? If you add new views to your application, I don't see why you cant reset it. Even plugin technologies sometimes requires you application to restart for wiring some events. Also there is no way to compile a class that is not know at compile time! How I said, you need to create interfaces and route information through your loaded dlls, because this will be known at compile time.

willver Over a year ago

I understand what you say, I've created all that structure, routing, interfaces, etc...The problem restarting the app is that I will lost sessions in the application, maybe I should create like a maintenance task and restart the application early in the morning after add a new plugin. But I prefer add a plugin without restart the main application, I can load the new links to the news views into the index page within the main application dynamically without restart.

rodrigogq Over a year ago

I would say that you should never let your application pool living for too long. You should restart it in a regular basis in order you don't run out of memory in your server. You can try using a webfarm for that, with sessions saved on SQL Server. Then your users would not be logged out.

willver Over a year ago

Yes, definitely that can be a solution using a SQL server to store the sessions.

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