Assembly resolving in ASP.NET project outside of bin folder

Question

How can i resolve assemblies references outside of bin folder of ASP.NET web-development server? This can be useful to not have copies of same dll's.

Nothing is working: probing element at web.config don't work, i can't set up domain because it do application manager, and i can't subscribe on the resolve assembly event because it's too late - when i can subscribe initialization is over. So what can i do?

Answer 1

Why use 'BuildManager.AddReferencedAssembly'?

In the 'Application_Start' method to bind event the 'AssemblyResolve' and set the Inherits with assembly name in the aspx page,no 'BuildManager.AddReferencedAssembly'.

Answer 2

We can use PreApplicationStartMethodAttribute and mark them some public static void method(in web-project assembly) with no arguments. This can be done at AssemblyInfo.cs class For example:

[assembly: PreApplicationStartMethod(
  typeof(Web.Initializer), "Initialize")]

That method will be called before compilation but after processing of the web.config. So we must explicitly tell to the compiler witch assembly it need to use during compilation. Also we need to subscribe here on Assembly Resolve event so we can manage assemblies resolving. Here is example:

  public static class Initializer
    {
        public static void Initialize()
        {
            AppDomain.CurrentDomain.AssemblyResolve += LoadFromCommonBinFolder;
            var referAsm = Assembly.GetExecutingAssembly().GetReferencedAssemblies();
            foreach (var assemblyName in referAsm)
            {
               try
               {
                var curAsm = Assembly.Load(assemblyName);
                BuildManager.AddReferencedAssembly(curAsm);
                LoadChildReferences(curAsm);
               }
               catch {}
            }
        }

    private static void LoadChildReferences(Assembly curAsm)
    {
       foreach (var assemblyName in curAsm.GetReferencedAssemblies())
       {
           try
           {
             BuildManager.AddReferencedAssembly(Assembly.Load(assemblyName));
           }
           catch {}
       }
    }

        private static Assembly LoadFromCommonBinFolder(object sender, ResolveEventArgs args)
        {
            string commonBinFolder = System.Configuration.ConfigurationManager.AppSettings["CommonBinFolderPath"];

            if (String.IsNullOrEmpty(commonBinFolder))
            {
                throw new InvalidOperationException("​​CommonBinFolderPath in the app.config isn't seted.");
            }

            string assemblyName = new AssemblyName(args.Name).Name;
            string assemblyPath = Path.Combine(commonBinFolder, assemblyName);

            if (!File.Exists(assemblyPath + ".dll"))
            {
                if (!File.Exists(assemblyPath + ".exe"))
                {
                    //searching for resources
                    var ci = CultureInfo.CurrentUICulture;
                    assemblyPath = Path.Combine(commonBinFolder, ci.Name, assemblyName + ".dll");
                    if (!File.Exists(assemblyPath))
                    {
                        assemblyPath = Path.Combine(commonBinFolder, ci.Parent, assemblyName + ".dll");
                        if (!File.Exists(assemblyPath))
                        {
                            return null;
                        }
                    }
                }
            }

            return Assembly.LoadFrom(assemblyPath);
        }
    }

At this case "Web.Project.Assembly" still must be located in the bin folder. Others assemblies can shared from any folder.

Assemblies that are included under compilation Element in the web.config file must be also in the bin folder or at sub folder with probing element setted.

In same cases we must also add to this code adding references to child assemblies.