Dynamically Load Referenced Assembly

[Adam R Harris]

Hey All, I have a problem with dynamically loading and referenced assembly at run time. The issue is that i am coding a 3rd party app for a larger application that is constantly getting patched and upgraded. Every time a new patch or upgrade comes out i need to recompile and redistribute the app too all the clients. Now nothing really ever changes in the referenced assembly aside from version number which is causing me to have to remove the reference and add it again. I don't even have to change code, just update the reference. I know i can load this specific assembly when the reference isn’t found by attaching to the AssemblyResolve event; however this is where I’m having problems. I’m not exactly sure how i should implement this. All the documentation i can find from MS isn’t very helpful, as per usual. Really the end goal is to have it load this referenced assembly when it is called at run time. The referenced assemblies path will change from machine to machine so it needs to fully dynamic, i can work out finding the proper assembly to load i just need some insight on the best way to implement this. Also another quick question ... if i reference say v1.2 and then dynamically load v3.5 is the framework going to freak out about the version numbers or just accept that this is the assembly i want to load. TIA

Don't comment your code - it was hard to write, it should be hard to read!

[Nish Nishant]

How are you loading them dynamically? You don't need to specify the version (assuming you are using Reflection) and instead can just load from a file path.

Regards, Nish

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[Adam R Harris]

First, thanks for the reply.

Nishant Sivakumar wrote:

How are you loading them dynamically?

Assembly.LoadFrom([path_to_assembly]) I will need to find the path to the assembly myself, which is not a problem. The problem is the proper implementation. I want to have a reference at design time, just set Copy To Local to false, and then at runtime actually go out and find the proper assembly on the client machine.

Nishant Sivakumar wrote:

You don't need to specify the version (assuming you are using Reflection) and instead can just load from a file path.

Just what i thought, thanks for confirming this. Thanks again for the reply

Don't comment your code - it was hard to write, it should be hard to read!

[Ennis Ray Lynch Jr]

Register the Assembly Resolve event before starting your applications message pump, or in the case of an ASP.NET application in the Application_Start event. Other than that, post a specific issue. I have never had a problem using Assembly resolve; it is fairly straight forward. Here is a copy and paste from another project with some namespaces removed.

using System;
using System.Data;
using System.Configuration;
using System.Reflection;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
namespace _Website {
public class AssemblyResolver {

	private bool mLoading = false;

	public AssemblyResolver(AppDomain appDomain) {
		appDomain.AssemblyResolve += new ResolveEventHandler(OnAssemblyResolve);
	}

	/\*\*
	 \* <summary>
	 \* This method will attempt to result assemblies
	 \* </summary>
	 \*/
	private Assembly OnAssemblyResolve(object sender, ResolveEventArgs args) {
		Assembly result = null;
		//Prevent Stack overflow, this method will recurse without this line
		if(!mLoading) {
			try {
				mLoading = true;
				IServiceBroker broker = ServiceRequests.CommonRequests.GetBroker();
				byte\[\] assembly = broker.ResolveAssembly();
				result = Assembly.Load(assembly);
			}//end try
			//catch(Exception e1) {
			//	e1 = e1;  //Used for debugging
			//}
			finally {
				mLoading = false;
			}
		}//end mLoading
		return result;
	}
}

}

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[Adam R Harris]

Fantastic, great implementation and pretty much exactly what i was looking for. Another thing, i am inheriting from classes inside the referenced assembly, is there a way to implement this for inheritence inside a class library? I tried throwing it inside the constructor, but it fails because when it goes to create the class it cant find the reference. I guess my question would be; is there a way to implement this globably for a class library? Thx for the reply

Don't comment your code - it was hard to write, it should be hard to read!