I'm trying to build a small tool for comparing types in a bunch of assemblies. For this purpose I created two subfolders and put the respective dlls there:
..\Dlls\v1.1..\Dlls\v1.2
where .. is the application folder
I also created a proxy object:
public class ProxyDomain : MarshalByRefObject
{
public Assembly LoadFile(string assemblyPath)
{
try
{
//Debug.WriteLine("CurrentDomain = " + AppDomain.CurrentDomain.FriendlyName);
return Assembly.LoadFile(assemblyPath);
}
catch (FileNotFoundException)
{
return null;
}
}
}
and used it for loading in the following routine that should load an dll and get all types declared in it:
private static HashSet<Type> LoadAssemblies(string version)
{
_currentVersion = version;
var path = Path.Combine(Environment.CurrentDirectory, Path.Combine(_assemblyDirectory, version));
var appDomainSetup = new AppDomainSetup
{
ApplicationBase = Environment.CurrentDirectory,
};
var evidence = AppDomain.CurrentDomain.Evidence;
var appDomain = AppDomain.CreateDomain("AppDomain" + version, evidence, appDomainSetup);
var proxyDomainType = typeof(ProxyDomain);
var proxyDomain = (ProxyDomain)appDomain.CreateInstanceAndUnwrap(proxyDomainType.Assembly.FullName, proxyDomainType.FullName);
_currentProxyDomain = proxyDomain;
var assemblies = new HashSet<Type>();
var files = Directory.GetFiles(path, "*.dll");
foreach (var file in files)
{
try
{
var assembly = proxyDomain.LoadFile(file);
if (assembly != null)
{
assemblies.UnionWith(assembly.DefinedTypes.Where(t => t.IsPublic));
}
}
catch (Exception)
{
}
}
return assemblies;
}
So far nothing unusual... but it didn't work like that in this case (probably because of the subfolders) so I searched a bit and found that a settting in the app.config might help so I tried to add two probing paths:
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<probing privatePath="Dlls\v1.1;Dlls\v1.2" />
</assemblyBinding>
</runtime>
Now there wasn't any FileNotFoundExpections anymore but as the dlls have the same names it loaded only dlls from the first subdirectory (v1.1) into both domains so I removed it and instead tried to implement the AppDomain.CurrentDomain.AssemblyResolve event handler like that:
AppDomain.CurrentDomain.AssemblyResolve += (sender, e) =>
{
var path = Path.Combine(Environment.CurrentDirectory, Path.Combine(_assemblyDirectory, _currentVersion));
path = Path.Combine(path, e.Name.Split(',').First());
path = path + ".dll";
var assembly = _currentProxyDomain.LoadFile(path);
return assembly;
};
But unfortunatelly with this event handler I created an infinite loop and it calls itself each time it tries to load a dll it cannot find. I have no more ideas what else I could try.
UPDATE-1
As @SimonMourier suggested I tried to use a custom .config for my new AppDomains and created two more *.configs like:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
</startup>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<probing privatePath="Dlls\v1.1" />
</assemblyBinding>
</runtime>
</configuration>
I named them v1.1.config and v1.2.config. Then I set the new ConfigurationFile property:
var appDomainSetup = new AppDomainSetup
{
ApplicationBase = Environment.CurrentDirectory,
ConfigurationFile = Path.Combine(Environment.CurrentDirectory, string.Format("{0}.config", version)),
};
I've set the option Copy to Output Directory to Copy always ;-)
It didn't work so I googled and tried another suggestion:
AppDomain.CurrentDomain.SetData("APP_CONFIG_FILE", appDomainSetup.ConfigurationFile);
but this didn't help either. Still FileNotFoundException like my custom configs weren't there.
Using the SetConfigurationBytes method instead had also no effect:
var domainConfig = @"
<configuration>
<startup>
<supportedRuntime version=""v4.0"" sku="".NETFramework,Version=v4.5"" />
</startup>
<runtime>
<assemblyBinding xmlns=""urn:schemas-microsoft-com:asm.v1"">
<probing privatePath=""Dlls\{0}"" />
</assemblyBinding>
</runtime>
</configuration>";
domainConfig = string.Format(domainConfig, version).Trim();
var probingBytes = Encoding.UTF8.GetBytes(domainConfig);
appDomainSetup.SetConfigurationBytes(probingBytes);
However if I call the GetData method the new appdomain uses the custom .config:
Debug.WriteLine("Current config: " + AppDomain.CurrentDomain.GetData("APP_CONFIG_FILE"));
It outputs the path that I set via ConfigurationFile
UPDATE-2
This is really confusing. The Stack Trace reveals that despite of what the GetData returs the Assembly.LoadFile still uses the original .config:
=== LOG: This bind starts in default load context. LOG: Using application configuration file:
C:[...]\bin\Debug\MyApp.exe.Config
LOG: Using host configuration file: LOG: Using machine configuration file from
C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
UPDATE-3
OK, I did some more experimenting and found out that by implementing @SimonMourier suggestion it indeed worked. The FileNotFoundException wasn't thrown by the LoadFile method in the ProxyDomain class but in the Main method of my app. I gues the assembly and the types are allowed to live only within the ProxyDomain context and cannot be transfered into the main domain as I have tried.
public IEnumerable<Type> LoadFile(string assemblyPath)
{
//try
{
// does't throw any exceptions
var assembly = Assembly.LoadFile(assemblyPath);
// returning the assembly itself or its types will throw an exception in the main application
return assembly.DefinedTypes;
}
//catch (FileNotFoundException)
{
// return null;
}
}
Method in the main domain:
private static HashSet<Type> LoadAssemblies(string version)
{
// omitted
foreach (var file in files)
{
//try
{
// the exception occurs here, when transfering types between domains:
var types = proxyDomain.LoadFile(file);
assemblies.UnionWith(types.Where(t => t.IsPublic));
}
}
// omitted
}
I'll need to rewrite the comparison algorithm now by at least the assemblies can be loaded ;-)
