CreateInstanceFromAndUnwrap from Azure Blob Storage

gistfile1.cs

using System;
using System.Diagnostics;
using System.Linq;
using System.Net;
using System.Security;
using System.Security.Permissions;
using System.Threading;
using Microsoft.WindowsAzure;
using Microsoft.WindowsAzure.ServiceRuntime;
using Microsoft.WindowsAzure.StorageClient;

namespace WorkerRole1
{
	public class WorkerRole : RoleEntryPoint
	{
		private ISample.ISample SampleAssembly;
		private AppDomain SampleAppDomain;

		public override void Run()
		{
			while (true)
			{
				Trace.WriteLine(SampleAssembly.Execute());

				Thread.Sleep(5000);
			}
		}

		public override void OnStop()
		{
			if (SampleAppDomain != null)
			{
				AppDomain.Unload(SampleAppDomain);
			}

			base.OnStop();
		}

		public override bool OnStart()
		{
			LoadAssembly(GetAssemblyUrl(), RoleEnvironment.GetConfigurationSettingValue("AssemblyTypeName"));

			RoleEnvironment.Changed += (s, e) =>
			{
				if (e.Changes.Any(chg => chg is RoleEnvironmentConfigurationSettingChange))
				{
					LoadAssembly(GetAssemblyUrl(), RoleEnvironment.GetConfigurationSettingValue("AssemblyTypeName"));
				}
			};

			return base.OnStart();
		}

		private void LoadAssembly(string AssemblyUrl,string AssemblyTypeName)
		{
			if (SampleAppDomain != null)
			{
				AppDomain.Unload(SampleAppDomain);
			}

			PermissionSet trustedLoadFromRemoteSourceGrantSet
				= new PermissionSet(PermissionState.Unrestricted);

			AppDomainSetup trustedLoadFromRemoteSourcesSetup = new AppDomainSetup();
				trustedLoadFromRemoteSourcesSetup.ApplicationBase =
					AppDomain.CurrentDomain.SetupInformation.ApplicationBase;

			SampleAppDomain = AppDomain.CreateDomain("SampleDomain", null, trustedLoadFromRemoteSourcesSetup, trustedLoadFromRemoteSourceGrantSet);
			var webpermission = new WebPermission(
						NetworkAccess.Connect,
						AssemblyUrl
					);
			SampleAppDomain.PermissionSet.SetPermission(webpermission);
			SampleAppDomain.PermissionSet.Demand();
			SampleAssembly = (ISample.ISample)SampleAppDomain.CreateInstanceFromAndUnwrap(AssemblyUrl, AssemblyTypeName);
		}

		private string GetAssemblyUrl()
		{
			var assemblyName = RoleEnvironment.GetConfigurationSettingValue("AssemblyBlobName");
			var assemblyContainerName = RoleEnvironment.GetConfigurationSettingValue("AssemblyBlobContainerName"); ;
			var connectionString = RoleEnvironment.GetConfigurationSettingValue("AssemblyBlobStorage"); ;

			var account = CloudStorageAccount.Parse(connectionString);
			var client = account.CreateCloudBlobClient();

			var assemblyBlobContainer = client.GetContainerReference(assemblyContainerName);

			var policy = new SharedAccessPolicy
			{
				Permissions = SharedAccessPermissions.Read,
				SharedAccessStartTime = DateTime.UtcNow.AddMinutes(-5),
				SharedAccessExpiryTime = DateTime.UtcNow + TimeSpan.FromMinutes(10)
			};

			CloudBlob blob = assemblyBlobContainer.GetBlobReference(assemblyName);
			var accessurl = blob.Uri.ToString() + blob.GetSharedAccessSignature(policy);
			Trace.WriteLine(accessurl);

			return accessurl;
		}
	}
}