How to Load an Assembly to AppDomain with all references recursively

Question

I want to load to a new AppDomain some assembly which has a complex references tree  MyDll dll -  Microsoft Office Interop Excel dll -  Microsoft Vbe Interop dll -  Office dll -  stdole dll   As far as I understood  when an assembly is being loaded to AppDomain  its references would not be loaded automatically  and I have to load them manually  So when I do   string dir     SomePath      different from AppDomain CurrentDomain BaseDirectory string path   System IO Path Combine dir   MyDll dll     AppDomainSetup setup   AppDomain CurrentDomain SetupInformation  setup ApplicationBase   dir  AppDomain domain   AppDomain CreateDomain  SomeAppDomain   null  setup    domain Load AssemblyName GetAssemblyName path      and got FileNotFoundException       Could not load file or assembly  MyDll  Version 1 0 0 0  Culture neutral  PublicKeyToken null  or one of its dependencies  The system cannot find the file specified    I think the key part is one of its dependencies   Ok  I do next before domain Load AssemblyName GetAssemblyName path     foreach  AssemblyName refAsmName in Assembly ReflectionOnlyLoadFrom path  GetReferencedAssemblies          domain Load refAsmName       But got FileNotFoundException again  on another  referenced  assembly   How to load all references recursively   Do I have to create references tree before loading root assembly  How to get an assembly s references without loading it

User · Answer

I have had to do this several times and have researched many different solutions.

The solution I find in most elegant and easy to accomplish can be implemented as such.

1. Create a project that you can create a simple interface

the interface will contain signatures of any members you wish to call.

public interface IExampleProxy
{
    string HelloWorld( string name );
}

Its important to keep this project clean and lite. It is a project that both AppDomain's can reference and will allow us to not reference the Assembly we wish to load in seprate domain from our client assembly.

2. Now create project that has the code you want to load in seperate `AppDomain`.

This project as with the client proj will reference the proxy proj and you will implement the interface.

public interface Example : MarshalByRefObject, IExampleProxy
{
    public string HelloWorld( string name )
    {
        return $"Hello '{ name }'";
    }
}

3. Next, in the client project, load code in another `AppDomain`.

So, now we create a new AppDomain. Can specify the base location for assembly references. Probing will check for dependent assemblies in GAC and in current directory and the AppDomain base loc.

// set up domain and create
AppDomainSetup domaininfo = new AppDomainSetup
{
    ApplicationBase = System.Environment.CurrentDirectory
};

Evidence adevidence = AppDomain.CurrentDomain.Evidence;

AppDomain exampleDomain = AppDomain.CreateDomain("Example", adevidence, domaininfo);

// assembly ant data names
var assemblyName = "<AssemblyName>, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null|<keyIfSigned>";
var exampleTypeName = "Example";

// Optional - get a reflection only assembly type reference
var @type = Assembly.ReflectionOnlyLoad( assemblyName ).GetType( exampleTypeName ); 

// create a instance of the `Example` and assign to proxy type variable
IExampleProxy proxy= ( IExampleProxy )exampleDomain.CreateInstanceAndUnwrap( assemblyName, exampleTypeName );

// Optional - if you got a type ref
IExampleProxy proxy= ( IExampleProxy )exampleDomain.CreateInstanceAndUnwrap( @type.Assembly.Name, @type.Name );    

// call any members you wish
var stringFromOtherAd = proxy.HelloWorld( "Tommy" );

// unload the `AppDomain`
AppDomain.Unload( exampleDomain );

if you need to, there are a ton of different ways to load an assembly. You can use a different way with this solution. If you have the assembly qualified name then I like to use the CreateInstanceAndUnwrap since it loads the assembly bytes and then instantiates your type for you and returns an object that you can simple cast to your proxy type or if you not that into strongly-typed code you could use the dynamic language runtime and assign the returned object to a dynamic typed variable then just call members on that directly.

There you have it.

This allows to load an assembly that your client proj doesnt have reference to in a seperate AppDomain and call members on it from client.

To test, I like to use the Modules window in Visual Studio. It will show you your client assembly domain and what all modules are loaded in that domain as well your new app domain and what assemblies or modules are loaded in that domain.

The key is to either make sure you code either derives MarshalByRefObject or is serializable.

`MarshalByRefObject will allow you to configure the lifetime of the domain its in. Example, say you want the domain to destroy if the proxy hasnt been called in 20 minutes.

I hope this helps.

User · Answer

The Key is the AssemblyResolve event raised by the AppDomain    STAThread  static void Main string   args        fileDialog ShowDialog        string fileName   fileDialog FileName      if  string IsNullOrEmpty fileName     false                AppDomain CurrentDomain AssemblyResolve    CurrentDomain AssemblyResolve          if  Directory Exists   c  Provisioning       false              Directory CreateDirectory   c  Provisioning              assemblyDirectory   Path GetDirectoryName fileName           Assembly loadedAssembly   Assembly LoadFile fileName            List lt Type gt  assemblyTypes   loadedAssembly GetTypes   ToList lt Type gt              foreach  var type in assemblyTypes                        if  type IsInterface    false                                StreamWriter jsonFile   File CreateText string Format   c  Provisioning  0  json   type Name                    JavaScriptSerializer serializer   new JavaScriptSerializer                    jsonFile WriteLine serializer Serialize Activator CreateInstance type                     jsonFile Close                                     static Assembly CurrentDomain AssemblyResolve object sender  ResolveEventArgs args        string   tokens   args Name Split     ToCharArray         System Diagnostics Debug WriteLine  Resolving       args Name       return Assembly LoadFile Path Combine new string   assemblyDirectory tokens 0     dll

User · Answer

It took me a while to understand  user1996230 s answer so I decided to provide a more explicit example  In the below example I make a proxy for an object loaded in another AppDomain and call a method on that object from another domain   class ProxyObject   MarshalByRefObject       private Type  type      private Object  object       public void InstantiateObject string AssemblyPath  string typeName  object   args                assembly   Assembly LoadFrom AppDomain CurrentDomain BaseDirectory   AssemblyPath     LoadFrom loads dependent DLLs  assuming they are in the app domain s base directory          type   assembly GetType typeName            object   Activator CreateInstance  type  args                public void InvokeMethod string methodName  object   args                var methodinfo    type GetMethod methodName           methodinfo Invoke  object  args            static void Main string   args        AppDomainSetup setup   new AppDomainSetup        setup ApplicationBase     SomePathWithDLLs       AppDomain domain   AppDomain CreateDomain  MyDomain   null  setup       ProxyObject proxyObject    ProxyObject domain CreateInstanceFromAndUnwrap typeof ProxyObject  Assembly Location  ProxyObject        proxyObject InstantiateObject  SomeDLL   SomeType   new object      someArgs        proxyObject InvokeMethod  foo  new object      bar

User · Answer

You need to invoke CreateInstanceAndUnwrap before your proxy object will execute in the foreign application domain    class Program       static void Main string   args                AppDomainSetup domaininfo   new AppDomainSetup            domaininfo ApplicationBase   System Environment CurrentDirectory          Evidence adevidence   AppDomain CurrentDomain Evidence          AppDomain domain   AppDomain CreateDomain  MyDomain   adevidence  domaininfo            Type type   typeof Proxy           var value    Proxy domain CreateInstanceAndUnwrap              type Assembly FullName              type FullName            var assembly   value GetAssembly args 0               AppDomain Unload domain            public class Proxy   MarshalByRefObject       public Assembly GetAssembly string assemblyPath                try                       return Assembly LoadFile assemblyPath                     catch  Exception                        return null                 throw new InvalidOperationException ex                       Also  note that if you use LoadFrom you ll likely get a FileNotFound exception because the Assembly resolver will attempt to find the assembly you re loading in the GAC or the current application s bin folder  Use LoadFile to load an arbitrary assembly file instead--but note that if you do this you ll need to load any dependencies yourself

User · Answer

You need to handle the AppDomain AssemblyResolve or AppDomain ReflectionOnlyAssemblyResolve events  depending on which load you re doing  in case the referenced assembly is not in the GAC or on the CLR s probing path   AppDomain AssemblyResolve  AppDomain ReflectionOnlyAssemblyResolve

User · Answer

http   support microsoft com kb 837908 en-us  C  version   Create a moderator class and inherit it from MarshalByRefObject   class ProxyDomain   MarshalByRefObject       public Assembly GetAssembly string assemblyPath                try                       return Assembly LoadFrom assemblyPath                     catch  Exception ex                        throw new InvalidOperationException ex Message                       call from client site  ProxyDomain pd   new ProxyDomain    Assembly assembly   pd GetAssembly assemblyFilePath

User · Answer

Once you pass the assembly instance back to the caller domain  the caller domain will try to load it  This is why you get the exception  This happens in your last line of code   domain Load AssemblyName GetAssemblyName path      Thus  whatever you want to do with the assembly  should be done in a proxy class - a class which inherit MarshalByRefObject   Take in count that the caller domain and the new created domain should both have access to the proxy class assembly  If your issue is not too complicated  consider leaving the ApplicationBase folder unchanged  so it will be same as the caller domain folder  the new domain will only load Assemblies it needs    In simple code   public void DoStuffInOtherDomain         const string assemblyPath      AsmPath        var newDomain   AppDomain CreateDomain  newDomain        var asmLoaderProxy    ProxyDomain newDomain CreateInstanceAndUnwrap Assembly GetExecutingAssembly   FullName  typeof ProxyDomain  FullName        asmLoaderProxy GetAssembly assemblyPath      class ProxyDomain   MarshalByRefObject       public void GetAssembly string AssemblyPath                try                       Assembly LoadFrom AssemblyPath                 If you want to do anything further to that assembly  you need to do it here                    catch  Exception ex                        throw new InvalidOperationException ex Message  ex                       If you do need to load the assemblies from a folder which is different than you current app domain folder  create the new app domain with specific dlls search path folder   For example  the app domain creation line from the above code should be replaced with   var dllsSearchPath      dlls search path for new app domain    AppDomain newDomain   AppDomain CreateDomain  newDomain   new Evidence    dllsSearchPath      true     This way  all the dlls will automaically be resolved from dllsSearchPath

User · Answer

On your new AppDomain  try setting an AssemblyResolve event handler   That event gets called when a dependency is missing

[c#] How to Load an Assembly to AppDomain with all references recursively?

1. Create a project that you can create a simple interface

2. Now create project that has the code you want to load in seperate `AppDomain`.

3. Next, in the client project, load code in another `AppDomain`.

There you have it.

To test, I like to use the Modules window in Visual Studio. It will show you your client assembly domain and what all modules are loaded in that domain as well your new app domain and what assemblies or modules are loaded in that domain.

I hope this helps.

Examples related to c#

Examples related to .net

Examples related to reflection

Examples related to assemblies

Examples related to appdomain

[c#] How to Load an Assembly to AppDomain with all references recursively?

1. Create a project that you can create a simple interface

2. Now create project that has the code you want to load in seperate AppDomain.

3. Next, in the client project, load code in another AppDomain.

There you have it.

To test, I like to use the Modules window in Visual Studio. It will show you your client assembly domain and what all modules are loaded in that domain as well your new app domain and what assemblies or modules are loaded in that domain.

I hope this helps.

Examples related to c#

Examples related to .net

Examples related to reflection

Examples related to assemblies

Examples related to appdomain

2. Now create project that has the code you want to load in seperate `AppDomain`.

3. Next, in the client project, load code in another `AppDomain`.