Adds IExternalInvoker

src/DurableSDK/ExternalInvoker.cs

@@ -0,0 +1,27 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.Azure.Functions.PowerShellWorker.Durable
+{
+    using System;
+    using System.Management.Automation;
+
+    internal class ExternalInvoker : IExternalInvoker
+    {
+        private readonly Func<PowerShell, object> _externalSDKInvokerFunction;
+        private readonly IPowerShellServices _powerShellServices;
+
+        public ExternalInvoker(Func<PowerShell, object> invokerFunction, IPowerShellServices powerShellServices)
+        {
+            _externalSDKInvokerFunction = invokerFunction;
+            _powerShellServices = powerShellServices;
+        }
+
+        public void Invoke()
+        {
+            _externalSDKInvokerFunction.Invoke(_powerShellServices.GetPowerShell());
+        }
+    }
+}

src/DurableSDK/IExternalInvoker.cs

@@ -0,0 +1,14 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.Azure.Functions.PowerShellWorker.Durable
+{
+    // Represents a contract for the 
+    internal interface IExternalInvoker
+    {
+        // Method to invoke an orchestration using the external Durable SDK
+        void Invoke();
+    }
+}

src/DurableSDK/IOrchestrationInvoker.cs

@@ -5,13 +5,11 @@
 
 namespace Microsoft.Azure.Functions.PowerShellWorker.Durable
 {
-    using System;
     using System.Collections;
-    using System.Management.Automation;
 
     internal interface IOrchestrationInvoker
     {
         Hashtable Invoke(OrchestrationBindingInfo orchestrationBindingInfo, IPowerShellServices pwsh);
-        void SetExternalInvoker(Action<PowerShell> externalInvoker);
+        void SetExternalInvoker(IExternalInvoker externalInvoker);
     }
 }

src/DurableSDK/IPowerShellServices.cs

@@ -17,7 +17,7 @@ internal interface IPowerShellServices
 
         void SetDurableClient(object durableClient);
 
-        OrchestrationBindingInfo SetOrchestrationContext(ParameterBinding orchestrationContext, out Action<object> externalInvoker);
+        OrchestrationBindingInfo SetOrchestrationContext(ParameterBinding context, out IExternalInvoker externalInvoker);
 
         void ClearOrchestrationContext();
 

src/DurableSDK/OrchestrationContext.cs

@@ -35,15 +35,16 @@ public class OrchestrationContext
 
         internal OrchestrationActionCollector OrchestrationActionCollector { get; } = new OrchestrationActionCollector();
 
-        internal object ExternalResult;
-        internal bool ExternalIsError;
+        internal object ExternalSDKResult;
+
+        internal bool ExternalSDKIsError;
 
         // Called by the External DF SDK to communicate its orchestration result
         // back to the worker.
         internal void SetExternalResult(object result, bool isError)
         {
-            this.ExternalResult = result;
-            this.ExternalIsError = isError;
+            this.ExternalSDKResult = result;
+            this.ExternalSDKIsError = isError;
         }
 
         internal object CustomStatus { get; set; }

src/DurableSDK/OrchestrationInvoker.cs

@@ -11,80 +11,95 @@ namespace Microsoft.Azure.Functions.PowerShellWorker.Durable
     using System.Linq;
     using System.Management.Automation;
 
-    // using PowerShellWorker.Utility;
     using Microsoft.Azure.Functions.PowerShellWorker.Durable.Actions;
 
     internal class OrchestrationInvoker : IOrchestrationInvoker
     {
-        private Action<PowerShell> externalInvoker = null;
+        private IExternalInvoker _externalInvoker;
 
-        public Hashtable Invoke(OrchestrationBindingInfo orchestrationBindingInfo, IPowerShellServices pwsh)
+        public Hashtable Invoke(
+            OrchestrationBindingInfo orchestrationBindingInfo,
+            IPowerShellServices powerShellServices)
         {
-
             try
             {
-                if (pwsh.UseExternalDurableSDK())
+                if (powerShellServices.UseExternalDurableSDK())
                 {
-                    externalInvoker.Invoke(pwsh.GetPowerShell());
-                    var result = orchestrationBindingInfo.Context.ExternalResult;
-                    var isError = orchestrationBindingInfo.Context.ExternalIsError;
-                    if (isError)
-                    {
-                        throw (Exception)result;
-                    }
-                    else
-                    {
-                        return (Hashtable)result;
-                    }
+                    return InvokeExternalDurableSDK(orchestrationBindingInfo, powerShellServices);
                 }
+                return InvokeInternalDurableSDK(orchestrationBindingInfo, powerShellServices);
+            }
+            finally
+            {
+                powerShellServices.ClearStreamsAndCommands();
+            }
+        }
 
-                var outputBuffer = new PSDataCollection<object>();
-                var context = orchestrationBindingInfo.Context;
+        public Hashtable InvokeExternalDurableSDK(
+            OrchestrationBindingInfo orchestrationBindingInfo,
+            IPowerShellServices powerShellServices)
+        {
 
-                // context.History should never be null when initializing CurrentUtcDateTime
-                var orchestrationStart = context.History.First(
-                    e => e.EventType == HistoryEventType.OrchestratorStarted);
-                context.CurrentUtcDateTime = orchestrationStart.Timestamp.ToUniversalTime();
+            _externalInvoker.Invoke();
+            var result = orchestrationBindingInfo.Context.ExternalSDKResult;
+            var isError = orchestrationBindingInfo.Context.ExternalSDKIsError;
+            if (isError)
+            {
+                throw (Exception)result;
+            }
+            else
+            {
+                return (Hashtable)result;
+            }
+        }
+
+        public Hashtable InvokeInternalDurableSDK(
+            OrchestrationBindingInfo orchestrationBindingInfo,
+            IPowerShellServices powerShellServices)
+        {
+            var outputBuffer = new PSDataCollection<object>();
+            var context = orchestrationBindingInfo.Context;
 
-                // Marks the first OrchestratorStarted event as processed
-                orchestrationStart.IsProcessed = true;
+            // context.History should never be null when initializing CurrentUtcDateTime
+            var orchestrationStart = context.History.First(
+                e => e.EventType == HistoryEventType.OrchestratorStarted);
+            context.CurrentUtcDateTime = orchestrationStart.Timestamp.ToUniversalTime();
 
-                // Finish initializing the Function invocation
-                pwsh.AddParameter(orchestrationBindingInfo.ParameterName, context);
-                pwsh.TracePipelineObject();
+            // Marks the first OrchestratorStarted event as processed
+            orchestrationStart.IsProcessed = true;
 
-                var asyncResult = pwsh.BeginInvoke(outputBuffer);
+            // Finish initializing the Function invocation
+            powerShellServices.AddParameter(orchestrationBindingInfo.ParameterName, context);
+            powerShellServices.TracePipelineObject();
 
-                var (shouldStop, actions) =
-                    orchestrationBindingInfo.Context.OrchestrationActionCollector.WaitForActions(asyncResult.AsyncWaitHandle);
+            var asyncResult = powerShellServices.BeginInvoke(outputBuffer);
 
-                if (shouldStop)
+            var (shouldStop, actions) =
+                orchestrationBindingInfo.Context.OrchestrationActionCollector.WaitForActions(asyncResult.AsyncWaitHandle);
+
+            if (shouldStop)
+            {
+                // The orchestration function should be stopped and restarted
+                powerShellServices.StopInvoke();
+                // return (Hashtable)orchestrationBindingInfo.Context.OrchestrationActionCollector.output;
+                return CreateOrchestrationResult(isDone: false, actions, output: null, context.CustomStatus);
+            }
+            else
+            {
+                try
                 {
-                    // The orchestration function should be stopped and restarted
-                    pwsh.StopInvoke();
-                    return CreateOrchestrationResult(isDone: false, actions, output: null, context.CustomStatus);
+                    // The orchestration function completed
+                    powerShellServices.EndInvoke(asyncResult);
+                    var result = CreateReturnValueFromFunctionOutput(outputBuffer);
+                    return CreateOrchestrationResult(isDone: true, actions, output: result, context.CustomStatus);
                 }
-                else
+                catch (Exception e)
                 {
-                    try
-                    {
-                        // The orchestration function completed
-                        pwsh.EndInvoke(asyncResult);
-                        var result = CreateReturnValueFromFunctionOutput(outputBuffer);
-                        return CreateOrchestrationResult(isDone: true, actions, output: result, context.CustomStatus);
-                    }
-                    catch (Exception e)
-                    {
-                        // The orchestrator code has thrown an unhandled exception:
-                        // this should be treated as an entire orchestration failure
-                        throw new OrchestrationFailureException(actions, context.CustomStatus, e);
-                    }
+                    // The orchestrator code has thrown an unhandled exception:
+                    // this should be treated as an entire orchestration failure
+                    throw new OrchestrationFailureException(actions, context.CustomStatus, e);
                 }
             }
-            finally
-            {
-                pwsh.ClearStreamsAndCommands();
-            }
         }
 
         public static object CreateReturnValueFromFunctionOutput(IList<object> pipelineItems)
@@ -107,9 +122,9 @@ private static Hashtable CreateOrchestrationResult(
             return new Hashtable { { "$return", orchestrationMessage } };
         }
 
-        public void SetExternalInvoker(Action<PowerShell> externalInvoker)
+        public void SetExternalInvoker(IExternalInvoker externalInvoker)
         {
-            this.externalInvoker = externalInvoker;
+            _externalInvoker = externalInvoker;
         }
     }
 }

src/DurableSDK/PowerShellServices.cs

@@ -25,7 +25,10 @@ internal class PowerShellServices : IPowerShellServices
 
         public PowerShellServices(PowerShell pwsh)
         {
-            // Attempt to import the external SDK
+            // We attempt to import the external SDK upon construction of the PowerShellServices object.
+            // We maintain the boolean member _useExternalDurableSDK in this object rather than
+            // DurableController because the expected input and functionality of SetFunctionInvocationContextCommand
+            // may differ between the internal and external implementations.
             try
             {
                 pwsh.AddCommand(Utils.ImportModuleCmdletInfo)
@@ -46,7 +49,7 @@ public PowerShellServices(PowerShell pwsh)
                 if (availableModules.Count() > 0)
                 {
                     // TODO: evaluate if there is a better error message or exception type to be throwing.
-                    // Ideally, this should never happen
+                    // Ideally, this should never happen.
                     throw new InvalidOperationException("The external Durable SDK was detected, but unable to be imported.", e);
                 }
                 _useExternalDurableSDK = false;
@@ -78,38 +81,46 @@ public void SetDurableClient(object durableClient)
             _pwsh.AddCommand(SetFunctionInvocationContextCommand)
                 .AddParameter("DurableClient", durableClient)
                 .InvokeAndClearCommands();
-
+            // TODO: is _hasSetOrchestrationContext properly named?
             _hasSetOrchestrationContext = true;
         }
 
-        public OrchestrationBindingInfo SetOrchestrationContext(ParameterBinding context, out Action<object> externalInvoker)
+        public OrchestrationBindingInfo SetOrchestrationContext(
+            ParameterBinding context,
+            out IExternalInvoker externalInvoker)
         {
             externalInvoker = null;
-            var orchBindingInfo = new OrchestrationBindingInfo(
+            OrchestrationBindingInfo orchestrationBindingInfo = new OrchestrationBindingInfo(
                 context.Name,
                 JsonConvert.DeserializeObject<OrchestrationContext>(context.Data.String));
 
             if (_useExternalDurableSDK)
             {
-                Collection<Action<object>> output = _pwsh.AddCommand(SetFunctionInvocationContextCommand)
+                Collection<Func<PowerShell, object>> output = _pwsh.AddCommand(SetFunctionInvocationContextCommand)
+                    // The external SetFunctionInvocationContextCommand expects a .json string to deserialize
+                    // and writes an invoker function to the output pipeline.
                     .AddParameter("OrchestrationContext", context.Data.String)
-                    .AddParameter("SetResult", (Action<object, bool>) orchBindingInfo.Context.SetExternalResult)
-                    .InvokeAndClearCommands<Action<object>>();
+                    .AddParameter("SetResult", (Action<object, bool>) orchestrationBindingInfo.Context.SetExternalResult)
+                    .InvokeAndClearCommands<Func<PowerShell, object>>();
                 if (output.Count() == 1)
                 {
-                    externalInvoker = output[0];
+                    externalInvoker = new ExternalInvoker(output[0], this);
+                }
+                else
+                {
+                    throw new InvalidOperationException($"Only a single output was expected for an invocation of {SetFunctionInvocationContextCommand}");
                 }
             }
             else
             {
                 _pwsh.AddCommand(SetFunctionInvocationContextCommand)
-                    .AddParameter("OrchestrationContext", orchBindingInfo.Context)
-                    .InvokeAndClearCommands<Action<object>>();
+                    .AddParameter("OrchestrationContext", orchestrationBindingInfo.Context)
+                    .InvokeAndClearCommands();
             }
-
             _hasSetOrchestrationContext = true;
-            return orchBindingInfo;
+            return orchestrationBindingInfo;
         }
+
 
         public void AddParameter(string name, object value)
         {

src/DurableWorker/DurableController.cs

@@ -67,12 +67,10 @@ public void InitializeBindings(IList<ParameterBinding> inputData)
             }
             else if (_durableFunctionInfo.IsOrchestrationFunction)
             {
-                var contextBindingData = inputData[0];
-                _orchestrationBindingInfo = _powerShellServices.SetOrchestrationContext(contextBindingData, out var externalInvoker);
-                if (externalInvoker != null)
-                {
-                    this._orchestrationInvoker.SetExternalInvoker(externalInvoker);
-                }
+                _orchestrationBindingInfo = _powerShellServices.SetOrchestrationContext(
+                    inputData[0],
+                    out IExternalInvoker externalInvoker);
+                _orchestrationInvoker.SetExternalInvoker(externalInvoker);
             }
         }
 

src/Modules/Microsoft.Azure.Functions.PowerShellWorker/Microsoft.Azure.Functions.PowerShellWorker.psm1

@@ -11,7 +11,7 @@ Set-Alias -Name Start-NewOrchestration -Value Start-DurableOrchestration
 
 function GetDurableClientFromModulePrivateData {
     $PrivateData = $PSCmdlet.MyInvocation.MyCommand.Module.PrivateData
-    if ($PrivateData -eq $null -or $PrivateData['DurableClient'] -eq $null) {
+    if ($null -eq $PrivateData -or $null -eq $PrivateData['DurableClient']) {
         throw "No binding of the type 'durableClient' was defined."
     }
     else {