CODEWITHSUNDEEP
c#.netmefhotswap
Dmitri Nesteruk
Dmitri Nesteruk

Reputation: 23789

Are there reference implementations of hot-swapping in .NET?

I'm looking for a good implementation of hot-swapping done in .NET. The things I need are:

I've been looking into MEF and its directory loading mechanism, but it seems very unreliable. Maybe someone out there has an alternative implementation?

Upvotes: 6

Views: 4492

Answers (1)

djv
djv

Reputation: 15774

You can provide a custom event handler for AssemblyResolve by calling newAppDomain() below. Supply your directory so AppDomain looks there. When loading a Type, use function loadFromAppDomain() to return it. This should allow you to copy new dlls to C:\dlls at runtime and reload from there. (Forgive me, I translated this from my VB source to C# according to your tag.)

String dllFolder = "C:\\dlls";

public void newAppDomain()
{
    AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(assemblyResolve);
}

private static Assembly assemblyResolve(Object sender, ResolveEventArgs args){
    String assemblyPath = Path.Combine(dllFolder, new AssemblyName(args.Name).Name + ".dll");
    if(!File.Exists(assemblyPath))
    {
        return null;
    }
    else
    {
        return Assembly.LoadFrom(assemblyPath);
    }
}

private Type loadFromAppDomain(String className)
{
    Assembly[] asses = AppDomain.CurrentDomain.GetAssemblies();
    List<Type> types = new List<Type>();
    foreach(Assembly ass in asses)
    {
        Type t = ass.GetType(className);
        if(t != null) types.Add(t);
    }
    if(types.Count == 1)
        return types.First();
    else
        return null;
}

Upvotes: 6

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