Add ability to push variables to scheduled work (#4306)

src/clients/Elsa.Api.Client/Resources/WorkflowInstances/Models/ActivityExecutionContextState.cs

@@ -1,3 +1,5 @@
+using Elsa.Api.Client.Resources.WorkflowDefinitions.Models;
+
 namespace Elsa.Api.Client.Resources.WorkflowInstances.Models;
 
 /// <summary>
@@ -34,4 +36,9 @@ public class ActivityExecutionContextState
     /// The evaluated values of the activity's properties.
     /// </summary>
     public IDictionary<string, object>? ActivityState { get; set; }
+
+    /// <summary>
+    /// A list of dynamically created variables.
+    /// </summary>
+    public ICollection<Variable> DynamicVariables { get; set; } = new List<Variable>();
 }

src/modules/Elsa.Dapper/Modules/Runtime/Stores/DapperWorkflowInboxStore.cs

@@ -8,7 +8,6 @@ using Elsa.Workflows.Core.Contracts;
 using Elsa.Workflows.Runtime.Contracts;
 using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Filters;
-using Elsa.Workflows.Runtime.Models;
 
 namespace Elsa.Dapper.Modules.Runtime.Stores;
 

src/modules/Elsa.EntityFrameworkCore.MySql/Migrations/Runtime/20230809080332_Initial.cs

@@ -1,5 +1,4 @@
-using System;
-using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

src/modules/Elsa.EntityFrameworkCore.PostgreSql/Migrations/Runtime/20230809080343_Initial.cs

@@ -1,5 +1,4 @@
-using System;
-using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

src/modules/Elsa.EntityFrameworkCore.SqlServer/Migrations/Runtime/20230809080335_Initial.cs

@@ -1,5 +1,4 @@
-using System;
-using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 

src/modules/Elsa.EntityFrameworkCore/Modules/Runtime/Configurations.cs

@@ -1,7 +1,6 @@
 using Elsa.Workflows.Core;
 using Elsa.Workflows.Core.State;
 using Elsa.Workflows.Runtime.Entities;
-using Elsa.Workflows.Runtime.Models;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Metadata.Builders;
 using Microsoft.EntityFrameworkCore.Storage.ValueConversion;

src/modules/Elsa.EntityFrameworkCore/Modules/Runtime/DbContext.cs

@@ -1,7 +1,6 @@
 using Elsa.EntityFrameworkCore.Common;
 using Elsa.Workflows.Core.State;
 using Elsa.Workflows.Runtime.Entities;
-using Elsa.Workflows.Runtime.Models;
 using Microsoft.EntityFrameworkCore;
 
 namespace Elsa.EntityFrameworkCore.Modules.Runtime;

src/modules/Elsa.EntityFrameworkCore/Modules/Runtime/WorkflowInboxStore.cs

@@ -4,7 +4,6 @@ using Elsa.Workflows.Core.Contracts;
 using Elsa.Workflows.Runtime.Contracts;
 using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Filters;
-using Elsa.Workflows.Runtime.Models;
 
 namespace Elsa.EntityFrameworkCore.Modules.Runtime;
 

src/modules/Elsa.EntityFrameworkCore/Modules/Runtime/WorkflowRuntimePersistenceFeature.cs

@@ -3,7 +3,6 @@ using Elsa.Features.Attributes;
 using Elsa.Features.Services;
 using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Features;
-using Elsa.Workflows.Runtime.Models;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace Elsa.EntityFrameworkCore.Modules.Runtime;

src/modules/Elsa.JavaScript/Services/JintJavaScriptEvaluator.cs

@@ -127,13 +127,9 @@ public class JintJavaScriptEvaluator : IJavaScriptEvaluator
 
     private static object GetVariableInScope(ExpressionExecutionContext context, string variableName)
     {
-        var q = from variable in EnumerateVariablesInScope(context)
-            where variable.Name == variableName
-            where variable.TryGet(context, out _)
-            select variable.Get(context);
-
-        var value = q.FirstOrDefault();
-
+        var variable = context.GetVariable(variableName);
+        var value = variable?.Get(context);
+        
         return ConvertIEnumerableToArray(value);
     }
 

src/modules/Elsa.MongoDb/Modules/Runtime/CreateIndices.cs

@@ -1,7 +1,6 @@
 using Elsa.MongoDb.Helpers;
 using Elsa.Workflows.Core.State;
 using Elsa.Workflows.Runtime.Entities;
-using Elsa.Workflows.Runtime.Models;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using MongoDB.Driver;

src/modules/Elsa.MongoDb/Modules/Runtime/WorkflowRuntimePersistenceFeature.cs

@@ -3,7 +3,6 @@ using Elsa.Features.Services;
 using Elsa.MongoDb.Common;
 using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Features;
-using Elsa.Workflows.Runtime.Models;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace Elsa.MongoDb.Modules.Runtime;

src/modules/Elsa.Telnyx/Activities/AnswerCallBase.cs

@@ -1,5 +1,4 @@
 using Elsa.Extensions;
-using Elsa.Telnyx.Attributes;
 using Elsa.Telnyx.Bookmarks;
 using Elsa.Telnyx.Client.Models;
 using Elsa.Telnyx.Client.Services;
@@ -8,7 +7,6 @@ using Elsa.Telnyx.Payloads.Call;
 using Elsa.Workflows.Core;
 using Elsa.Workflows.Core.Attributes;
 using Elsa.Workflows.Core.Models;
-using Elsa.Workflows.Runtime.Contracts;
 using Refit;
 
 namespace Elsa.Telnyx.Activities;

src/modules/Elsa.Telnyx/Activities/BridgeCallsBase.cs

@@ -9,7 +9,6 @@ using Elsa.Telnyx.Payloads.Call;
 using Elsa.Workflows.Core;
 using Elsa.Workflows.Core.Attributes;
 using Elsa.Workflows.Core.Models;
-using Elsa.Workflows.Runtime.Contracts;
 using JetBrains.Annotations;
 using Refit;
 

src/modules/Elsa.Telnyx/Activities/GatherUsingSpeak.cs

@@ -10,7 +10,6 @@ using Elsa.Workflows.Core;
 using Elsa.Workflows.Core.Activities.Flowchart.Attributes;
 using Elsa.Workflows.Core.Attributes;
 using Elsa.Workflows.Core.Models;
-using Elsa.Workflows.Runtime.Contracts;
 using Refit;
 
 namespace Elsa.Telnyx.Activities;

src/modules/Elsa.Telnyx/Activities/PlayAudioBase.cs

@@ -9,7 +9,6 @@ using Elsa.Workflows.Core;
 using Elsa.Workflows.Core.Activities.Flowchart.Attributes;
 using Elsa.Workflows.Core.Attributes;
 using Elsa.Workflows.Core.Models;
-using Elsa.Workflows.Runtime.Contracts;
 using Refit;
 
 namespace Elsa.Telnyx.Activities;

src/modules/Elsa.Telnyx/Handlers/TriggerAnswerCallActivities.cs

@@ -4,7 +4,6 @@ using Elsa.Telnyx.Activities;
 using Elsa.Telnyx.Bookmarks;
 using Elsa.Telnyx.Events;
 using Elsa.Telnyx.Extensions;
-using Elsa.Telnyx.Payloads.Abstract;
 using Elsa.Telnyx.Payloads.Call;
 using Elsa.Workflows.Core.Helpers;
 using Elsa.Workflows.Runtime.Contracts;

src/modules/Elsa.Telnyx/Handlers/TriggerCallAnsweredActivities.cs

@@ -4,7 +4,6 @@ using Elsa.Telnyx.Activities;
 using Elsa.Telnyx.Bookmarks;
 using Elsa.Telnyx.Events;
 using Elsa.Telnyx.Extensions;
-using Elsa.Telnyx.Payloads.Abstract;
 using Elsa.Telnyx.Payloads.Call;
 using Elsa.Workflows.Core.Helpers;
 using Elsa.Workflows.Runtime.Contracts;

src/modules/Elsa.Telnyx/Handlers/TriggerCallHangupActivities.cs

@@ -4,7 +4,6 @@ using Elsa.Telnyx.Activities;
 using Elsa.Telnyx.Bookmarks;
 using Elsa.Telnyx.Events;
 using Elsa.Telnyx.Extensions;
-using Elsa.Telnyx.Payloads.Abstract;
 using Elsa.Telnyx.Payloads.Call;
 using Elsa.Workflows.Core.Helpers;
 using Elsa.Workflows.Runtime.Contracts;

src/modules/Elsa.Telnyx/Handlers/TriggerIncomingCallActivities.cs

@@ -4,7 +4,6 @@ using Elsa.Telnyx.Activities;
 using Elsa.Telnyx.Bookmarks;
 using Elsa.Telnyx.Events;
 using Elsa.Telnyx.Extensions;
-using Elsa.Telnyx.Payloads.Abstract;
 using Elsa.Telnyx.Payloads.Call;
 using Elsa.Workflows.Core.Helpers;
 using Elsa.Workflows.Runtime.Contracts;

src/modules/Elsa.Workflows.Core/Activities/Parallel.cs

@@ -3,7 +3,6 @@ using System.Runtime.CompilerServices;
 using Elsa.Extensions;
 using Elsa.Workflows.Core.Attributes;
 using Elsa.Workflows.Core.Contracts;
-using JetBrains.Annotations;
 
 namespace Elsa.Workflows.Core.Activities;
 

src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs

@@ -1,9 +1,11 @@
-using System.ComponentModel;
 using System.Runtime.CompilerServices;
+using Elsa.Expressions.Helpers;
 using Elsa.Extensions;
 using Elsa.Workflows.Core.Attributes;
 using Elsa.Workflows.Core.Contracts;
+using Elsa.Workflows.Core.Memory;
 using Elsa.Workflows.Core.Models;
+using Elsa.Workflows.Core.Services;
 
 namespace Elsa.Workflows.Core.Activities;
 
@@ -25,7 +27,7 @@ public class ParallelForEach<T> : Activity
     /// <summary>
     /// The items to iterate.
     /// </summary>
-    [Input(Description = "The items to iterate.")]
+    [Input(Description = "The items to iterate through.")]
     public Input<ICollection<T>> Items { get; set; } = new(Array.Empty<T>());
 
     /// <summary>
@@ -37,17 +39,27 @@ public class ParallelForEach<T> : Activity
     /// <inheritdoc />
     protected override async ValueTask ExecuteAsync(ActivityExecutionContext context)
     {
-        var items = context.Get(Items)!.Reverse().ToList();
+        var items = context.Get(Items)!.ToList();
         var tags = new List<Guid>();
 
         foreach (var item in items)
         {
-            // TODO: For each item, declare a new block of memory to store the item into.
+            // For each item, declare a new variable the work to be scheduled.
+            var variable = new Variable<T>("CurrentItem", item)
+            {
+                // TODO: This should be configurable, because this won't work for e.g. file streams and other non-serializable types.
+                StorageDriverType = typeof(WorkflowStorageDriver)
+            };
+            
+            var variables = new List<Variable<T>>
+            {
+                variable
+            };
 
             // Schedule a body of work for each item.
             var tag = Guid.NewGuid();
             tags.Add(tag);
-            await context.ScheduleActivityAsync(Body, OnChildCompleted, tag);
+            await context.ScheduleActivityAsync(Body, OnChildCompleted, tag, variables);
         }
 
         context.SetProperty(ScheduledTagsProperty, tags);
@@ -57,7 +69,7 @@ public class ParallelForEach<T> : Activity
     private async ValueTask OnChildCompleted(ActivityExecutionContext context, ActivityExecutionContext childContext)
     {
         var scheduledTags = context.GetProperty<List<Guid>>(ScheduledTagsProperty)!;
-        var completedTag = (Guid)childContext.Tag!;
+        var completedTag = childContext.Tag.ConvertTo<Guid>();
 
         var completedTags = new HashSet<Guid>(context.UpdateProperty<List<Guid>>(CompletedTagsProperty, completedTags =>
         {

src/modules/Elsa.Workflows.Core/Contexts/ActivityExecutionContext.cs

@@ -7,6 +7,7 @@ using Elsa.Extensions;
 using Elsa.Workflows.Core.Contracts;
 using Elsa.Workflows.Core.Memory;
 using Elsa.Workflows.Core.Models;
+using Elsa.Workflows.Core.Options;
 using Elsa.Workflows.Core.Services;
 
 namespace Elsa.Workflows.Core;
@@ -87,7 +88,20 @@ public class ActivityExecutionContext : IExecutionContext
     public ExpressionExecutionContext ExpressionExecutionContext { get; }
 
     /// <inheritdoc />
-    public IEnumerable<Variable> Variables => (Activity as IVariableContainer)?.Variables ?? Enumerable.Empty<Variable>();
+    public IEnumerable<Variable> Variables
+    {
+        get
+        {
+            var containerVariables = (Activity as IVariableContainer)?.Variables ?? Enumerable.Empty<Variable>();
+            var dynamicVariables = DynamicVariables;
+            return containerVariables.Concat(dynamicVariables).DistinctBy(x => x.Name);
+        }
+    }
+
+    /// <summary>
+    /// A list of variables that are dynamically added to the activity execution context.
+    /// </summary>
+    public ICollection<Variable> DynamicVariables { get; set; } = new List<Variable>();
 
     /// <summary>
     /// The currently executing activity.
@@ -159,47 +173,49 @@ public class ActivityExecutionContext : IExecutionContext
     /// Schedules the specified activity to be executed.
     /// </summary>
     /// <param name="activity">The activity to schedule.</param>
-    /// <param name="completionCallback">An optional callback that is invoked when the activity completes.</param>
-    /// <param name="tag">An optional tag that can be used to identify the activity.</param>
-    public async ValueTask ScheduleActivityAsync(IActivity? activity, ActivityCompletionCallback? completionCallback = default, object? tag = default)
+    /// <param name="completionCallback">An optional callback to invoke when the activity completes.</param>
+    /// <param name="tag">An optional tag to associate with the activity execution.</param>
+    /// <param name="variables">An optional list of variables to declare with the activity execution.</param>
+    public async ValueTask ScheduleActivityAsync(IActivity? activity, ActivityCompletionCallback? completionCallback, object? tag = default, IEnumerable<Variable>? variables = default)
     {
-        var activityNode = activity != null ? WorkflowExecutionContext.FindNodeByActivity(activity) : default;
-        await ScheduleActivityAsync(activityNode, completionCallback, tag);
+        var options = new ScheduleWorkOptions(completionCallback, tag, variables);
+        await ScheduleActivityAsync(activity, options);
     }
 
     /// <summary>
     /// Schedules the specified activity to be executed.
     /// </summary>
     /// <param name="activity">The activity to schedule.</param>
-    /// <param name="owner">The activity execution context that owns the activity.</param>
-    /// <param name="completionCallback">An optional callback that is invoked when the activity completes.</param>
-    /// <param name="tag">An optional tag that can be used to identify the activity.</param>
-    public async ValueTask ScheduleActivityAsync(IActivity? activity, ActivityExecutionContext owner, ActivityCompletionCallback? completionCallback = default, object? tag = default)
+    /// <param name="options">The options used to schedule the activity.</param>
+    public async ValueTask ScheduleActivityAsync(IActivity? activity, ScheduleWorkOptions? options = default)
     {
         var activityNode = activity != null ? WorkflowExecutionContext.FindNodeByActivity(activity) : default;
-        await ScheduleActivityAsync(activityNode, this, completionCallback, tag);
+        await ScheduleActivityAsync(activityNode, this, options);
     }
 
     /// <summary>
     /// Schedules the specified activity to be executed.
     /// </summary>
-    /// <param name="activityNode">The activity node to schedule.</param>
-    /// <param name="completionCallback">An optional callback that is invoked when the activity completes.</param>
-    /// <param name="tag">An optional tag that can be used to identify the activity.</param>
-    public async ValueTask ScheduleActivityAsync(ActivityNode? activityNode, ActivityCompletionCallback? completionCallback = default, object? tag = default)
+    /// <param name="activity">The activity to schedule.</param>
+    /// <param name="owner">The activity execution context that owns the scheduled activity.</param>
+    /// <param name="options">The options used to schedule the activity.</param>
+    public async ValueTask ScheduleActivityAsync(IActivity? activity, ActivityExecutionContext? owner, ScheduleWorkOptions? options = default)
     {
-        await ScheduleActivityAsync(activityNode, this, completionCallback, tag);
+        var activityNode = activity != null ? WorkflowExecutionContext.FindNodeByActivity(activity) : default;
+        await ScheduleActivityAsync(activityNode, owner, options);
     }
-
+    
     /// <summary>
     /// Schedules the specified activity to be executed.
     /// </summary>
     /// <param name="activityNode">The activity node to schedule.</param>
-    /// <param name="owner">The activity execution context that owns the activity.</param>
-    /// <param name="completionCallback">An optional callback that is invoked when the activity completes.</param>
-    /// <param name="tag">An optional tag that can be used to identify the activity.</param>
-    public async ValueTask ScheduleActivityAsync(ActivityNode? activityNode, ActivityExecutionContext owner, ActivityCompletionCallback? completionCallback = default, object? tag = default)
+    /// <param name="owner">The activity execution context that owns the scheduled activity.</param>
+    /// <param name="options">The options used to schedule the activity.</param>
+    public async ValueTask ScheduleActivityAsync(ActivityNode? activityNode, ActivityExecutionContext? owner = default, ScheduleWorkOptions? options = default)
     {
+        var completionCallback = options?.CompletionCallback;
+        owner ??= this;
+
         if (activityNode == null)
         {
             if (completionCallback != null)
@@ -209,7 +225,7 @@ public class ActivityExecutionContext : IExecutionContext
             return;
         }
 
-        WorkflowExecutionContext.Schedule(activityNode, owner, completionCallback, tag);
+        WorkflowExecutionContext.Schedule(activityNode, owner, options);
     }
 
     /// <summary>
@@ -222,11 +238,24 @@ public class ActivityExecutionContext : IExecutionContext
     /// Schedules the specified activities to be executed.
     /// </summary>
     /// <param name="activities">The activities to schedule.</param>
-    /// <param name="completionCallback">An optional callback that is invoked for each activity when it completes.</param>
-    public async ValueTask ScheduleActivities(IEnumerable<IActivity?> activities, ActivityCompletionCallback? completionCallback = default)
+    /// <param name="completionCallback">The callback to invoke when the activities complete.</param>
+    /// <param name="tag">An optional tag to associate with the activity execution.</param>
+    /// <param name="variables">An optional list of variables to declare with the activity execution.</param>
+    public async ValueTask ScheduleActivities(IEnumerable<IActivity?> activities, ActivityCompletionCallback? completionCallback, object? tag = default, IEnumerable<Variable>? variables = default)
+    {
+        var options = new ScheduleWorkOptions(completionCallback, tag, variables);
+        await ScheduleActivities(activities, options);
+    }
+
+    /// <summary>
+    /// Schedules the specified activities to be executed.
+    /// </summary>
+    /// <param name="activities">The activities to schedule.</param>
+    /// <param name="options">The options used to schedule the activities.</param>
+    public async ValueTask ScheduleActivities(IEnumerable<IActivity?> activities, ScheduleWorkOptions? options = default)
     {
         foreach (var activity in activities)
-            await ScheduleActivityAsync(activity, completionCallback);
+            await ScheduleActivityAsync(activity, options);
     }
 
     /// <summary>

src/modules/Elsa.Workflows.Core/Contexts/WorkflowExecutionContext.cs

@@ -9,6 +9,7 @@ using Elsa.Common.Contracts;
 using Elsa.Workflows.Core.Activities;
 using Elsa.Workflows.Core.Memory;
 using Elsa.Workflows.Core.Models;
+using Elsa.Workflows.Core.Options;
 using JetBrains.Annotations;
 
 namespace Elsa.Workflows.Core;
@@ -122,7 +123,7 @@ public class WorkflowExecutionContext : IExecutionContext
     /// The date and time the workflow execution context was created.
     /// </summary>
     public DateTimeOffset CreatedAt { get; set; }
-    
+
     /// <summary>
     /// A flattened list of <see cref="ActivityNode"/>s from the <see cref="Graph"/>. 
     /// </summary>
@@ -373,16 +374,34 @@ public class WorkflowExecutionContext : IExecutionContext
     /// <summary>
     /// Creates a new <see cref="ActivityExecutionContext"/> for the specified activity.
     /// </summary>
-    public ActivityExecutionContext CreateActivityExecutionContext(IActivity activity, ActivityExecutionContext? parentContext = default, object? tag = default)
+    public ActivityExecutionContext CreateActivityExecutionContext(IActivity activity, ActivityInvocationOptions? options = default)
     {
         var activityDescriptor = _activityRegistry.Find(activity) ?? throw new Exception($"Activity with type {activity.Type} not found in registry");
+        var tag = options?.Tag;
+        var parentContext = options?.Owner;
         var parentExpressionExecutionContext = parentContext?.ExpressionExecutionContext ?? ExpressionExecutionContext;
         var properties = ExpressionExecutionContextExtensions.CreateActivityExecutionContextPropertiesFrom(this, Input);
         var memory = new MemoryRegister();
         var now = _systemClock.UtcNow;
         var expressionExecutionContext = new ExpressionExecutionContext(_serviceProvider, memory, parentExpressionExecutionContext, properties, CancellationToken);
         var activityExecutionContext = new ActivityExecutionContext(this, parentContext, expressionExecutionContext, activity, activityDescriptor, now, tag, _systemClock, CancellationToken);
+        var variablesToDeclare = options?.Variables ?? Array.Empty<Variable>();
+        var variableContainer = new[] { activityExecutionContext.ActivityNode }.Concat(activityExecutionContext.ActivityNode.Ancestors()).FirstOrDefault(x => x.Activity is IVariableContainer)?.Activity as IVariableContainer;
         expressionExecutionContext.TransientProperties[ExpressionExecutionContextExtensions.ActivityExecutionContextKey] = activityExecutionContext;
+
+        if (variableContainer != null)
+        {
+            foreach (var variable in variablesToDeclare)
+            {
+                // Declare a dynamic variable on the activity execution context.
+                activityExecutionContext.DynamicVariables.RemoveWhere(x => x.Name == variable.Name);
+                activityExecutionContext.DynamicVariables.Add(variable);
+                
+                // Assign the variable to the expression execution context.
+                expressionExecutionContext.CreateVariable(variable.Name, variable.Value);
+            }
+        }
+
         return activityExecutionContext;
     }
 

src/modules/Elsa.Workflows.Core/Contracts/IActivityInvoker.cs

@@ -1,3 +1,5 @@
+using Elsa.Workflows.Core.Options;
+
 namespace Elsa.Workflows.Core.Contracts;
 
 /// <summary>
@@ -10,12 +12,8 @@ public interface IActivityInvoker
     /// </summary>
     /// <param name="workflowExecutionContext">The workflow execution context.</param>
     /// <param name="activity">The activity to invoke.</param>
-    /// <param name="owner">The activity execution context that owns the activity.</param>
-    /// <param name="tag">An optional tag to associate with the activity execution.</param>
-    Task InvokeAsync(WorkflowExecutionContext workflowExecutionContext,
-        IActivity activity,
-        ActivityExecutionContext? owner = default, 
-        object? tag = default);
+    /// <param name="options"></param>
+    Task InvokeAsync(WorkflowExecutionContext workflowExecutionContext, IActivity activity, ActivityInvocationOptions? options = default);
 
     /// <summary>
     /// Invokes the specified activity execution context.

src/modules/Elsa.Workflows.Core/Contracts/IExecutionContext.cs

@@ -19,7 +19,7 @@ public interface IExecutionContext
     ExpressionExecutionContext ExpressionExecutionContext { get; }
     
     /// <summary>
-    /// Returns variables declared the current execution context.
+    /// Returns variables declared in the current execution context.
     /// </summary>
     IEnumerable<Variable> Variables { get; }
 

src/modules/Elsa.Workflows.Core/Elsa.Workflows.Core.csproj

@@ -27,8 +27,4 @@
         <ProjectReference Include="..\Elsa.Expressions\Elsa.Expressions.csproj" />
     </ItemGroup>
 
-    <ItemGroup>
-      <Folder Include="Bookmarks\" />
-    </ItemGroup>
-
 </Project>

src/modules/Elsa.Workflows.Core/Extensions/ActivityExecutionContextExtensions.cs

@@ -230,8 +230,7 @@ public static class ActivityExecutionContextExtensions
     }
 
     /// <summary>
-    /// Schedules the specified activity with the provided callback.
-    /// If the activity is null, the callback is invoked immediately.
+    /// Schedules the specified activity.
     /// </summary>
     public static async Task ScheduleOutcomeAsync(this ActivityExecutionContext context, IActivity? activity, [CallerArgumentExpression("activity")] string portPropertyName = default!)
     {

src/modules/Elsa.Workflows.Core/Extensions/ExpressionExecutionContextExtensions.cs

@@ -47,7 +47,7 @@ public static class ExpressionExecutionContextExtensions
     public static object? Get(this ExpressionExecutionContext context, Output output) => context.GetBlock(output.MemoryBlockReference).Value;
     public static T? GetVariable<T>(this ExpressionExecutionContext context, string name) => (T?)context.GetVariable(name)?.Value;
 
-    private static Variable? GetVariable(this ExpressionExecutionContext context, string name)
+    public static Variable? GetVariable(this ExpressionExecutionContext context, string name)
     {
         foreach (var block in context.Memory.Blocks.Where(b => b.Value.Metadata is VariableBlockMetadata))
         {
@@ -59,9 +59,13 @@ public static class ExpressionExecutionContextExtensions
         return context.ParentContext?.GetVariable(name);
     }
 
+    /// <summary>
+    /// Creates a named variable in the context.
+    /// </summary>
     public static Variable CreateVariable<T>(this ExpressionExecutionContext context, string name, T? value, Type? storageDriverType = null, Action<MemoryBlock>? configure = default)
     {
         var existingVariable = context.GetVariable(name);
+        
         if(existingVariable != null)
             throw new Exception($"Variable {name} already exists in the context.");
         
@@ -74,17 +78,24 @@ public static class ExpressionExecutionContextExtensions
         return variable;
     }
 
+    /// <summary>
+    /// Sets the value of a named variable in the context.
+    /// </summary>
     public static Variable SetVariable<T>(this ExpressionExecutionContext context, string name, T? value, Action<MemoryBlock>? configure = default)
     {
         var variable = context.GetVariable(name);
-        if(variable is null)
-            throw new Exception($"Variable {name} not found in the context.");
+        
+        if(variable == null)
+            return CreateVariable(context, name, value, configure: configure);
 
         variable.Value = value;
         variable.Set(context, value, configure);
         return variable;
     }
 
+    /// <summary>
+    /// Sets the output to the specified value.
+    /// </summary>
     public static void Set(this ExpressionExecutionContext context, Output? output, object? value, Action<MemoryBlock>? configure = default)
     {
         if (output != null) context.Set(output.MemoryBlockReference(), value, configure);
@@ -107,11 +118,9 @@ public static class ExpressionExecutionContextExtensions
         while (currentContext != null)
         {
             var register = currentContext.Memory;
-            foreach (var entry in register.Blocks)
-            {
-                if (!memoryBlocks.ContainsKey(entry.Key))
-                    memoryBlocks.Add(entry.Key, entry.Value);
-            }
+            
+            foreach (var entry in register.Blocks) 
+                memoryBlocks.TryAdd(entry.Key, entry.Value);
 
             currentContext = currentContext.ParentContext;
         }

src/modules/Elsa.Workflows.Core/Extensions/WorkflowExecutionContextExtensions.cs

@@ -1,7 +1,7 @@
 using Elsa.Workflows.Core;
 using Elsa.Workflows.Core.Contracts;
 using Elsa.Workflows.Core.Models;
-using Elsa.Workflows.Core.Services;
+using Elsa.Workflows.Core.Options;
 
 // ReSharper disable once CheckNamespace
 namespace Elsa.Extensions;
@@ -98,13 +98,15 @@ public static class WorkflowExecutionContextExtensions
         this WorkflowExecutionContext workflowExecutionContext,
         ActivityNode activityNode,
         ActivityExecutionContext owner,
-        ActivityCompletionCallback? completionCallback = default,
-        object? tag = default)
+        ScheduleWorkOptions? options = default)
     {
         var activityInvoker = workflowExecutionContext.GetRequiredService<IActivityInvoker>();
         var toolVersion = workflowExecutionContext.Workflow.ToolVersion;
         var activityId = toolVersion.Major >= 3 ? activityNode.Activity.Id : activityNode.NodeId;
-        var workItem = new ActivityWorkItem(activityId, owner.Id, async () => await activityInvoker.InvokeAsync(workflowExecutionContext, activityNode.Activity, owner, tag), tag);
+        var tag = options?.Tag;
+        var activityInvocationOptions = new ActivityInvocationOptions(owner, tag, options?.Variables);
+        var workItem = new ActivityWorkItem(activityId, owner.Id, async () => await activityInvoker.InvokeAsync(workflowExecutionContext, activityNode.Activity, activityInvocationOptions), tag);
+        var completionCallback = options?.CompletionCallback;
         workflowExecutionContext.Scheduler.Schedule(workItem);
         workflowExecutionContext.AddCompletionCallback(owner, activityNode, completionCallback);
     }

src/modules/Elsa.Workflows.Core/Options/ActivityInvocationOptions.cs

@@ -0,0 +1,11 @@
+using Elsa.Workflows.Core.Memory;
+
+namespace Elsa.Workflows.Core.Options;
+
+/// <summary>
+/// Represents options for invoking an activity.
+/// </summary>
+/// <param name="Owner">The activity execution context that owns this invocation.</param>
+/// <param name="Tag">An optional tag that can be used to identify the invocation.</param>
+/// <param name="Variables">The variables to declare in the activity execution context that will be created for this invocation.</param>
+public record ActivityInvocationOptions(ActivityExecutionContext? Owner, object? Tag, IEnumerable<Variable>? Variables);

src/modules/Elsa.Workflows.Core/Options/ScheduleWorkOptions.cs

@@ -0,0 +1,12 @@
+using Elsa.Workflows.Core.Memory;
+using Elsa.Workflows.Core.Services;
+
+namespace Elsa.Workflows.Core.Options;
+
+/// <summary>
+/// Represents options for scheduling a work item.
+/// </summary>
+/// <param name="CompletionCallback">The callback to invoke when the work item has completed.</param>
+/// <param name="Tag">A tag that can be used to identify the work item.</param>
+/// <param name="Variables">A collection of variables to declare in the activity execution context that will be created for this work item.</param>
+public record ScheduleWorkOptions(ActivityCompletionCallback? CompletionCallback = default, object? Tag = default, IEnumerable<Variable>? Variables = default);

src/modules/Elsa.Workflows.Core/Services/ActivityInvoker.cs

@@ -1,4 +1,5 @@
 using Elsa.Workflows.Core.Contracts;
+using Elsa.Workflows.Core.Options;
 
 namespace Elsa.Workflows.Core.Services;
 
@@ -16,13 +17,10 @@ public class ActivityInvoker : IActivityInvoker
     }
 
     /// <inheritdoc />
-    public async Task InvokeAsync(WorkflowExecutionContext workflowExecutionContext,
-        IActivity activity,
-        ActivityExecutionContext? owner, 
-        object? tag)
+    public async Task InvokeAsync(WorkflowExecutionContext workflowExecutionContext, IActivity activity, ActivityInvocationOptions? options = default)
     {
         // Setup an activity execution context.
-        var activityExecutionContext = workflowExecutionContext.CreateActivityExecutionContext(activity, owner, tag);
+        var activityExecutionContext = workflowExecutionContext.CreateActivityExecutionContext(activity, options);
 
         // Add the activity context to the workflow context.
         workflowExecutionContext.AddActivityExecutionContext(activityExecutionContext);

src/modules/Elsa.Workflows.Core/Services/WorkflowExecutionContextMapper.cs

@@ -112,7 +112,9 @@ public class WorkflowExecutionContextMapper : IWorkflowExecutionContextMapper
                 Status = activityExecutionContext.Status,
                 StartedAt = activityExecutionContext.StartedAt,
                 CompletedAt = activityExecutionContext.CompletedAt,
-                Tag = activityExecutionContext.Tag
+                Tag = activityExecutionContext.Tag,
+                DynamicVariables = activityExecutionContext.DynamicVariables
+                
             };
             return activityExecutionContextState;
         }
@@ -135,6 +137,7 @@ public class WorkflowExecutionContextMapper : IWorkflowExecutionContextMapper
             activityExecutionContext.StartedAt = activityExecutionContextState.StartedAt;
             activityExecutionContext.CompletedAt = activityExecutionContextState.CompletedAt;
             activityExecutionContext.Tag = activityExecutionContextState.Tag;
+            activityExecutionContext.DynamicVariables = activityExecutionContextState.DynamicVariables;
 
             return activityExecutionContext;
         }

src/modules/Elsa.Workflows.Core/State/ActivityExecutionContextState.cs

@@ -1,3 +1,5 @@
+using Elsa.Workflows.Core.Memory;
+
 namespace Elsa.Workflows.Core.State;
 
 /// <summary>
@@ -43,6 +45,11 @@ public class ActivityExecutionContextState
     /// The evaluated values of the activity's properties.
     /// </summary>
     public IDictionary<string, object>? ActivityState { get; set; }
+    
+    /// <summary>
+    /// A list of dynamically created variables.
+    /// </summary>
+    public ICollection<Variable> DynamicVariables { get; set; } = new List<Variable>();
 
     /// <summary>
     /// The status of the activity.

src/modules/Elsa.Workflows.Runtime/Contracts/IWorkflowInboxStore.cs

@@ -1,6 +1,5 @@
 using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Filters;
-using Elsa.Workflows.Runtime.Models;
 
 namespace Elsa.Workflows.Runtime.Contracts;
 

src/modules/Elsa.Workflows.Runtime/Features/WorkflowRuntimeFeature.cs

@@ -14,7 +14,6 @@ using Elsa.Workflows.Runtime.Contracts;
 using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Handlers;
 using Elsa.Workflows.Runtime.HostedServices;
-using Elsa.Workflows.Runtime.Models;
 using Elsa.Workflows.Runtime.Options;
 using Elsa.Workflows.Runtime.Providers;
 using Elsa.Workflows.Runtime.Services;

src/modules/Elsa.Workflows.Runtime/Filters/WorkflowInboxMessageFilter.cs

@@ -1,5 +1,4 @@
 using Elsa.Workflows.Runtime.Entities;
-using Elsa.Workflows.Runtime.Models;
 
 namespace Elsa.Workflows.Runtime.Filters;
 

src/modules/Elsa.Workflows.Runtime/Notifications/WorkflowInboxMessageReceived.cs

@@ -1,7 +1,6 @@
 using Elsa.Mediator.Contracts;
 using Elsa.Workflows.Runtime.Contracts;
 using Elsa.Workflows.Runtime.Entities;
-using Elsa.Workflows.Runtime.Models;
 
 namespace Elsa.Workflows.Runtime.Notifications;
 

src/modules/Elsa.Workflows.Runtime/Results/SubmitWorkflowInboxMessageResult.cs

@@ -1,6 +1,5 @@
 using Elsa.Workflows.Runtime.Contracts;
 using Elsa.Workflows.Runtime.Entities;
-using Elsa.Workflows.Runtime.Models;
 
 namespace Elsa.Workflows.Runtime.Results;
 

src/modules/Elsa.Workflows.Runtime/Stores/MemoryWorkflowInboxStore.cs

@@ -2,7 +2,6 @@ using Elsa.Common.Services;
 using Elsa.Workflows.Runtime.Contracts;
 using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Filters;
-using Elsa.Workflows.Runtime.Models;
 
 namespace Elsa.Workflows.Runtime.Stores;