Loading Assemblies

Question

I need to manually load some unresolved dlls that are embedded in my code. I am having some issues with that and now reduced the code to the following very simple plugin shown below. When this plugin executes I get the exception:

Unexpected exception from plug-in (Execute): test.MyPlugin: System.TypeInitializationException: The type initializer for 'test.MyTest' threw an exception. The line that fails is AppDomain... If I replace that line with AppDomain a = AppDomain.CurrentDomain; then there is no issue. So somehow I cannot add a handler. Unfortunately, I can't see any inner exceptions or step through as the plugin runs on a hosted server to which I have no access. Any ideas are appreciated.

using System;
using Microsoft.Xrm.Sdk;

namespace test {
    public class MyPlugin : IPlugin {
        public void Execute(IServiceProvider serviceProvider) {
            MyTest log = new MyTest();
        }
    }
    public class MyTest {
        static MyTest() {
            AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(CurrentDomain_AssemblyResolve);
        }

        static System.Reflection.Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args) {
            return null;
        }
    }
}

Answer 1

Hi,

I don't think it is wise to add event handlers to the Plugin Pipeline AppDomain - you would need to ensure that the event is un-registered when the plugin is re-registered etc. and at best this would be an unsupported customisation.

Options are:

1) Use ILMerge to combine all the dependancies into a single assembly

2) Register the dependant assemblies in the gac (if you are using an OnPrem deployment)

3) Combine all the dependancies into a single code base so that there is a single compiled assembly.

Option 3 would be the best option, especially if you are using CRM Online.

hth,

Scott

---

Scott Durow
Read my blog: www.develop1.net/public
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Answer 2

Thanks for the response. Since I use CRM Online 2) is out. Regarding 3) are you suggesting that I put all source code into one big project and compile it into one dll? The issue with this is that I don't have access to the source of some dlls. If I misunderstood then can you please clarify some more?

I did actually use 1) but ran into issues when adding Enterprise Library to the mix. After adding that library I get to different errors (sometimes one and sometimes the other). I guess some dlls are loaded in the background and it just matters what is done first. The errors are:

[plugin name]: System.TypeLoadException: Inheritance security rules violated by type Microsoft.Practices.EnterpriseLibrary.Common.Instrumentation.CommonWmiInstaller. Derived types must either match the security accessibility of the base type or be less accessible.

[plugin name]: System.ArgumentException: The specified type Xrm.AsyncOperation is not a known entity name.

The first one is related to to Enterprise Libraries. The second one was never an issue until I added Enterprise Library to the ILMerge. For some reason suddenly AsyncOperation is not visible anymore although I ILMerge it and although I have the [assembly: Microsoft.Xrm.Sdk.Client.ProxyTypesAssemblyAttribute()].

If I can continue to use ILMerge that would be preferred.

Answer 3

Hi,

The issues you are encountering are not un-common with ILMerge unfortunately - the process interferes with type dependancies and refelection. The enterprise library is open-source - so you can compile that in to your plugin assembly.

Scott

---

Scott Durow
Read my blog: www.develop1.net/public
If this post answers your question, please click "Mark As Answer" on the post and "Mark as Helpful"