Can this library work as Plugin Loader?

[aloksharma1]

Hello,

Instead of Modules i want my assembly subparts to behave as plugins, load/unload on runtime without affecting host app. Can you guide me how this is possible with this library, currently i am using DotnetCorePlugins
but this have bug in razor that your library solves, so i am interested if i can port to yours.

thanks

[John0King]

Can this library work as Plugin Loader

yes, but you may want to use DotnetCorePlugins because this project is in slow development and for reseach purpose currently (no officol release on nuget.org)

but this have bug in razor that your library solves

well, there are only two ways to acrchve plugins, 1). Assembly.Load and use MemeoryStream or byte[] 2) AssemblyLoadContext aka ALC. the problem that razor happed is that the razor is load to Default ALC in "hard code" way (ps: .net 6 + Source Generator should fixed this because now the razor files are generat .g.cs in your project obj folder and there are no additional assembly need to be load).
and (for below .net 6 ) this project fix it in a very simple way , it add a fallback method to the default ALC and forward it to the plugin ALC.

LazyMan.ModularLoader/test/SubAppTest/HostApp/Startup.cs

Lines 47 to 78 in cb805ed

	// razor bug fix
	AssemblyLoadContext.Default.Resolving += (alc, asbn) =>
	{
	return AssemblyLoadContext.All.OfType<PluginAssemblyLoadContext>()
	.Where(x => x.PluginInfo.PluginName.Equals(asbn.Name, StringComparison.OrdinalIgnoreCase))
	.FirstOrDefault()?.LoadFromAssemblyName(asbn);
	//if (AssemblyLoadContext.CurrentContextualReflectionContext == null)
	//{
	// return null;
	//}
	//if (AssemblyLoadContext.CurrentContextualReflectionContext == alc)
	//{
	// return null;
	//}
	//if (dic.TryGetValue(asbn.FullName, out var c))
	//{
	// if (c > 0)
	// {
	// return null;
	// }
	//}
	//if (dic.ContainsKey(asbn.FullName))
	//{
	// dic[asbn.FullName] = dic[asbn.FullName] + 1;
	//}
	//else
	//{
	// dic[asbn.FullName] = 0;
	//}
	//return AssemblyLoadContext.CurrentContextualReflectionContext.LoadFromAssemblyName(asbn);
	};
	app.UseSubAppModules("/m");

and that means you can not make a razor dll's assembly name as same as other plugins (because the way that razor add to Default ALC is not compatiable with the "Plugin architecture" )

[John0King]

be notice that unloadable ALC have many limit as #1 meation ,
for example :

• unloadable ALC must not use dynamic proxy
• all asp.net core assembly must in "plugin host"
• only work with "framework dependend publish" (all because the 2nd issue, you must very careful to not add any host used asembly in your plugin, otherwise the Type mismatch as I meation in focusing on AssemblyLoadContext.CurrentContextualReflectionContext to support child/parent alc fallback dotnet/runtime#37576)

and thats why this project no active develop.

[aloksharma1]

ok, so i will try to do this in net 6 but i am also ready to wait till net 7 if that's going to solve these issues that you have pointed out.
i am very careful about point 2 as all development follow one common project as reference assembly holder+host & plugin folders only use specific refernces when/if required and not available in main project.