StateMachineSubscriptionManager.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / WF / Activities / StateMachineSubscriptionManager.cs / 1305376 / StateMachineSubscriptionManager.cs

                            #region Using directives 

using System;
using System.Collections;
using System.Collections.Generic; 
using System.Collections.Specialized;
using System.Reflection; 
using System.Diagnostics; 
using System.Runtime.Remoting.Messaging;
using System.Workflow.ComponentModel; 
using System.Workflow.ComponentModel.Design;
using System.Workflow.Runtime;
using System.Workflow.Runtime.Hosting;
 
#endregion Using directives
 
namespace System.Workflow.Activities 
{
    [Serializable] 
    internal class StateMachineSubscriptionManager
    {
        private SetStateSubscription _setStateSubscription;
        private List _eventQueue = new List(); 
        private Dictionary _subscriptions = new Dictionary();
        private StateMachineExecutionState _executionState; 
 
        internal StateMachineSubscriptionManager(StateMachineExecutionState executionState, Guid instanceId)
        { 
            _executionState = executionState;
            _setStateSubscription = new SetStateSubscription(instanceId);
        }
 
        #region Properties
        private List EventQueue 
        { 
            get
            { 
                return this._eventQueue;
            }
        }
 
        internal StateMachineExecutionState ExecutionState
        { 
            get 
            {
                return _executionState; 
            }
        }

        internal Dictionary Subscriptions 
        {
            get 
            { 
                return this._subscriptions;
            } 
        }

        internal SetStateSubscription SetStateSubscription
        { 
            get
            { 
                return _setStateSubscription; 
            }
        } 

        #endregion Properties

        internal void UnsubscribeState(ActivityExecutionContext context) 
        {
            StateActivity state = (StateActivity)context.Activity; 
            foreach (Activity childActivity in state.EnabledActivities) 
            {
                EventDrivenActivity eventDriven = childActivity as EventDrivenActivity; 
                if (eventDriven != null)
                {
                    if (IsEventDrivenSubscribed(eventDriven))
                        UnsubscribeEventDriven(context, eventDriven); 
                }
            } 
        } 

        internal void ReevaluateSubscriptions(ActivityExecutionContext context) 
        {
            Dictionary subscriptions = this.GetSubscriptionsShallowCopy();
            List subscribed = new List();
 
            StateActivity state = StateMachineHelpers.GetCurrentState(context);
            while (state != null) 
            { 

                foreach (Activity activity in state.EnabledActivities) 
                {
                    EventDrivenActivity eventDriven = activity as EventDrivenActivity;
                    if (eventDriven == null)
                        continue; 

                    IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven); 
                    IComparable queueName = eventActivity.QueueName; 
                    if (queueName == null)
                        continue; 

                    StateMachineSubscription subscription;
                    subscriptions.TryGetValue(queueName, out subscription);
                    EventActivitySubscription eventActivitySubscription = subscription as EventActivitySubscription; 
                    if (eventActivitySubscription != null)
                    { 
                        if (eventActivitySubscription.EventDrivenName.Equals(eventDriven.QualifiedName)) 
                        {
                            // this EventDriven is already subscribed 
                            subscribed.Add(queueName);
                            continue;
                        }
                        else 
                        {
                            // Check if this state already subscribe to this event 
                            // if so, throws, since it is not valid to subscribe to the 
                            // same event twice
                            if (eventActivitySubscription.StateName.Equals(state.QualifiedName)) 
                                throw new InvalidOperationException(SR.GetStateAlreadySubscribesToThisEvent(state.QualifiedName, queueName));

                            // some other EventDriven is subscribed, so we need to unsubscribe if
                            // the event driven belongs to one of our parents 
                            if (IsParentState(state, eventActivitySubscription.StateName))
                            { 
                                UnsubscribeAction unsubscribe = new UnsubscribeAction(eventActivitySubscription.StateName, eventActivitySubscription.EventDrivenName); 
                                this.ExecutionState.EnqueueAction(unsubscribe);
                                subscriptions.Remove(queueName); 
                            }
                        }
                    }
 
                    // Tests if a child state already subscribes to this event
                    // is so, skip, since the child takes precedence 
                    if (subscribed.Contains(queueName)) 
                        continue;
 
                    SubscribeAction subscribe = new SubscribeAction(state.QualifiedName, eventDriven.QualifiedName);
                    this.ExecutionState.EnqueueAction(subscribe);
                    subscribed.Add(queueName);
                } 

                state = state.Parent as StateActivity; 
            } 

            StateActivity currentState = StateMachineHelpers.GetCurrentState(context); 
            DisableQueuesAction disableQueues = new DisableQueuesAction(currentState.QualifiedName);
            this.ExecutionState.EnqueueAction(disableQueues);
        }
 
        private bool IsParentState(StateActivity state, string stateName)
        { 
            StateActivity parentState = state.Parent as StateActivity; 
            while (parentState != null)
            { 
                if (parentState.QualifiedName.Equals(stateName))
                    return true;
                parentState = parentState.Parent as StateActivity;
            } 
            return false;
        } 
 
        internal void SubscribeEventDriven(ActivityExecutionContext context, EventDrivenActivity eventDriven)
        { 
            IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven);
            Activity activity = (Activity)eventActivity;
            IComparable queueName = GetQueueName(eventActivity);
            Debug.Assert(!this.Subscriptions.ContainsKey(queueName)); 
            SubscribeEventActivity(context, eventActivity);
        } 
 
        internal void UnsubscribeEventDriven(ActivityExecutionContext context, EventDrivenActivity eventDriven)
        { 
            Debug.Assert(IsEventDrivenSubscribed(eventDriven));
            IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven);
            UnsubscribeEventActivity(context, eventActivity);
        } 

        private StateMachineSubscription SubscribeEventActivity(ActivityExecutionContext context, 
            IEventActivity eventActivity) 
        {
            EventActivitySubscription subscription = new EventActivitySubscription(); 
            StateActivity state = (StateActivity)context.Activity;
            subscription.Subscribe(context, state, eventActivity);
            WorkflowQueue workflowQueue = GetWorkflowQueue(context, subscription.QueueName);
            if (workflowQueue != null) 
                workflowQueue.Enabled = true;
 
            Debug.Assert(subscription.QueueName != null); 
            this.Subscriptions[subscription.QueueName] = subscription;
 
            return subscription;
        }

        private void UnsubscribeEventActivity(ActivityExecutionContext context, 
            IEventActivity eventActivity)
        { 
            if (context == null) 
                throw new ArgumentNullException("context");
            if (eventActivity == null) 
                throw new ArgumentNullException("eventActivity");

            EventActivitySubscription subscription = GetSubscription(eventActivity);
            WorkflowQueue workflowQueue = GetWorkflowQueue(context, subscription.QueueName); 
            if (workflowQueue != null)
                workflowQueue.Enabled = false; 
            UnsubscribeEventActivity(context, eventActivity, subscription); 
        }
 
        private void UnsubscribeEventActivity(ActivityExecutionContext context,
            IEventActivity eventActivity,
            EventActivitySubscription subscription)
        { 
            if (context == null)
                throw new ArgumentNullException("context"); 
            if (eventActivity == null) 
                throw new ArgumentNullException("eventActivity");
            if (subscription == null) 
                throw new ArgumentNullException("subscription");

            subscription.Unsubscribe(context, eventActivity);
            RemoveFromQueue(subscription.SubscriptionId); 

            Debug.Assert(subscription.QueueName != null); 
            this.Subscriptions.Remove(subscription.QueueName); 
        }
 
        internal void CreateSetStateEventQueue(ActivityExecutionContext context)
        {
            this.SetStateSubscription.CreateQueue(context);
            this.Subscriptions[this.SetStateSubscription.SubscriptionId] = this.SetStateSubscription; 
        }
 
        internal void DeleteSetStateEventQueue(ActivityExecutionContext context) 
        {
            this.Subscriptions[this.SetStateSubscription.SubscriptionId] = null; 
            this.SetStateSubscription.DeleteQueue(context);
        }

        internal void SubscribeToSetStateEvent(ActivityExecutionContext context) 
        {
            this.SetStateSubscription.Subscribe(context); 
            this.Subscriptions[this.SetStateSubscription.SubscriptionId] = this.SetStateSubscription; 
        }
 
        internal void UnsubscribeToSetStateEvent(ActivityExecutionContext context)
        {
            this.Subscriptions[this.SetStateSubscription.SubscriptionId] = null;
            this.SetStateSubscription.Unsubscribe(context); 
        }
 
        private bool IsEventDrivenSubscribed(EventDrivenActivity eventDriven) 
        {
            IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven); 
            EventActivitySubscription subscription = GetSubscription(eventActivity);
            return (subscription != null);
        }
 
        private EventActivitySubscription GetSubscription(IEventActivity eventActivity)
        { 
            IComparable queueName = GetQueueName(eventActivity); 
            if ((queueName == null) || (!this.Subscriptions.ContainsKey(queueName)))
                return null; 

            EventActivitySubscription subscription = this.Subscriptions[queueName] as EventActivitySubscription;

            Activity activity = (Activity)eventActivity; 
            if (subscription == null ||
                subscription.EventActivityName != activity.QualifiedName) 
                return null; 

            return subscription; 
        }

        private StateMachineSubscription GetSubscription(IComparable queueName)
        { 
            StateMachineSubscription subscription;
            this.Subscriptions.TryGetValue(queueName, out subscription); 
            return subscription; 
        }
 
        /* Currently not used, left here for completeness
        internal static void EnableStateWorkflowQueues(ActivityExecutionContext context, StateActivity state)
        {
            ChangeStateWorkflowQueuesState(context, state, true); 
        }
        */ 
 
        internal static void DisableStateWorkflowQueues(ActivityExecutionContext context, StateActivity state)
        { 
            ChangeStateWorkflowQueuesState(context, state, false);
        }

        private static void ChangeStateWorkflowQueuesState(ActivityExecutionContext context, StateActivity state, bool enabled) 
        {
            foreach (Activity activity in state.EnabledActivities) 
            { 
                EventDrivenActivity eventDriven = activity as EventDrivenActivity;
                if (eventDriven != null) 
                    ChangeEventDrivenQueueState(context, eventDriven, enabled);
            }
        }
 
        internal static void ChangeEventDrivenQueueState(ActivityExecutionContext context, EventDrivenActivity eventDriven, bool enabled)
        { 
            IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven); 
            IComparable queueName = GetQueueName(eventActivity);
            if (queueName == null) 
                return; // skip unitialized follower
            WorkflowQueue workflowQueue = GetWorkflowQueue(context, queueName);
            if (workflowQueue != null)
                workflowQueue.Enabled = enabled; 
        }
 
        internal static WorkflowQueue GetWorkflowQueue(ActivityExecutionContext context, IComparable queueName) 
        {
            WorkflowQueuingService workflowQueuingService = context.GetService(); 
            if (workflowQueuingService.Exists(queueName))
            {
                WorkflowQueue workflowQueue = workflowQueuingService.GetWorkflowQueue(queueName);
                return workflowQueue; 
            }
            return null; 
        } 

        private static IComparable GetQueueName(IEventActivity eventActivity) 
        {
            IComparable queueName = eventActivity.QueueName;
            return queueName;
        } 

        private Dictionary GetSubscriptionsShallowCopy() 
        { 
            Dictionary subscriptions = new Dictionary();
            foreach (KeyValuePair dictionaryEntry in this.Subscriptions) 
            {
                subscriptions.Add(dictionaryEntry.Key, dictionaryEntry.Value);
            }
            return subscriptions; 
        }
 
        #region Event Queue Methods 

        internal void Enqueue(ActivityExecutionContext context, Guid subscriptionId) 
        {
            StateMachineSubscription subscription = GetSubscription(subscriptionId);
            if (subscription != null)
            { 
                // subscription can be null if we already unsubscribed to
                // this event 
                this.EventQueue.Add(subscription); 
            }
            ProcessQueue(context); 
        }

        internal void Enqueue(ActivityExecutionContext context, IComparable queueName)
        { 
            StateMachineSubscription subscription = GetSubscription(queueName);
            if (subscription != null) 
            { 
                // subscription can be null if we already unsubscribed to
                // this event 
                this.EventQueue.Add(subscription);
            }
            ProcessQueue(context);
        } 

        internal StateMachineSubscription Dequeue() 
        { 
            StateMachineSubscription subscription = this.EventQueue[0];
            this.EventQueue.RemoveAt(0); 
            return subscription;
        }

        private void RemoveFromQueue(Guid subscriptionId) 
        {
            this.EventQueue.RemoveAll(delegate(StateMachineSubscription subscription) { return subscription.SubscriptionId.Equals(subscriptionId); }); 
        } 

        internal void ProcessQueue(ActivityExecutionContext context) 
        {
            StateActivity currentState = StateMachineHelpers.GetCurrentState(context);
            if (this.EventQueue.Count == 0 ||
                this.ExecutionState.HasEnqueuedActions || 
                this.ExecutionState.SchedulerBusy ||
                currentState == null) 
                return; 

            StateMachineSubscription subscription = Dequeue(); 
            subscription.ProcessEvent(context);
        }

        #endregion Event Queue Methods 

    } 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
#region Using directives 

using System;
using System.Collections;
using System.Collections.Generic; 
using System.Collections.Specialized;
using System.Reflection; 
using System.Diagnostics; 
using System.Runtime.Remoting.Messaging;
using System.Workflow.ComponentModel; 
using System.Workflow.ComponentModel.Design;
using System.Workflow.Runtime;
using System.Workflow.Runtime.Hosting;
 
#endregion Using directives
 
namespace System.Workflow.Activities 
{
    [Serializable] 
    internal class StateMachineSubscriptionManager
    {
        private SetStateSubscription _setStateSubscription;
        private List _eventQueue = new List(); 
        private Dictionary _subscriptions = new Dictionary();
        private StateMachineExecutionState _executionState; 
 
        internal StateMachineSubscriptionManager(StateMachineExecutionState executionState, Guid instanceId)
        { 
            _executionState = executionState;
            _setStateSubscription = new SetStateSubscription(instanceId);
        }
 
        #region Properties
        private List EventQueue 
        { 
            get
            { 
                return this._eventQueue;
            }
        }
 
        internal StateMachineExecutionState ExecutionState
        { 
            get 
            {
                return _executionState; 
            }
        }

        internal Dictionary Subscriptions 
        {
            get 
            { 
                return this._subscriptions;
            } 
        }

        internal SetStateSubscription SetStateSubscription
        { 
            get
            { 
                return _setStateSubscription; 
            }
        } 

        #endregion Properties

        internal void UnsubscribeState(ActivityExecutionContext context) 
        {
            StateActivity state = (StateActivity)context.Activity; 
            foreach (Activity childActivity in state.EnabledActivities) 
            {
                EventDrivenActivity eventDriven = childActivity as EventDrivenActivity; 
                if (eventDriven != null)
                {
                    if (IsEventDrivenSubscribed(eventDriven))
                        UnsubscribeEventDriven(context, eventDriven); 
                }
            } 
        } 

        internal void ReevaluateSubscriptions(ActivityExecutionContext context) 
        {
            Dictionary subscriptions = this.GetSubscriptionsShallowCopy();
            List subscribed = new List();
 
            StateActivity state = StateMachineHelpers.GetCurrentState(context);
            while (state != null) 
            { 

                foreach (Activity activity in state.EnabledActivities) 
                {
                    EventDrivenActivity eventDriven = activity as EventDrivenActivity;
                    if (eventDriven == null)
                        continue; 

                    IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven); 
                    IComparable queueName = eventActivity.QueueName; 
                    if (queueName == null)
                        continue; 

                    StateMachineSubscription subscription;
                    subscriptions.TryGetValue(queueName, out subscription);
                    EventActivitySubscription eventActivitySubscription = subscription as EventActivitySubscription; 
                    if (eventActivitySubscription != null)
                    { 
                        if (eventActivitySubscription.EventDrivenName.Equals(eventDriven.QualifiedName)) 
                        {
                            // this EventDriven is already subscribed 
                            subscribed.Add(queueName);
                            continue;
                        }
                        else 
                        {
                            // Check if this state already subscribe to this event 
                            // if so, throws, since it is not valid to subscribe to the 
                            // same event twice
                            if (eventActivitySubscription.StateName.Equals(state.QualifiedName)) 
                                throw new InvalidOperationException(SR.GetStateAlreadySubscribesToThisEvent(state.QualifiedName, queueName));

                            // some other EventDriven is subscribed, so we need to unsubscribe if
                            // the event driven belongs to one of our parents 
                            if (IsParentState(state, eventActivitySubscription.StateName))
                            { 
                                UnsubscribeAction unsubscribe = new UnsubscribeAction(eventActivitySubscription.StateName, eventActivitySubscription.EventDrivenName); 
                                this.ExecutionState.EnqueueAction(unsubscribe);
                                subscriptions.Remove(queueName); 
                            }
                        }
                    }
 
                    // Tests if a child state already subscribes to this event
                    // is so, skip, since the child takes precedence 
                    if (subscribed.Contains(queueName)) 
                        continue;
 
                    SubscribeAction subscribe = new SubscribeAction(state.QualifiedName, eventDriven.QualifiedName);
                    this.ExecutionState.EnqueueAction(subscribe);
                    subscribed.Add(queueName);
                } 

                state = state.Parent as StateActivity; 
            } 

            StateActivity currentState = StateMachineHelpers.GetCurrentState(context); 
            DisableQueuesAction disableQueues = new DisableQueuesAction(currentState.QualifiedName);
            this.ExecutionState.EnqueueAction(disableQueues);
        }
 
        private bool IsParentState(StateActivity state, string stateName)
        { 
            StateActivity parentState = state.Parent as StateActivity; 
            while (parentState != null)
            { 
                if (parentState.QualifiedName.Equals(stateName))
                    return true;
                parentState = parentState.Parent as StateActivity;
            } 
            return false;
        } 
 
        internal void SubscribeEventDriven(ActivityExecutionContext context, EventDrivenActivity eventDriven)
        { 
            IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven);
            Activity activity = (Activity)eventActivity;
            IComparable queueName = GetQueueName(eventActivity);
            Debug.Assert(!this.Subscriptions.ContainsKey(queueName)); 
            SubscribeEventActivity(context, eventActivity);
        } 
 
        internal void UnsubscribeEventDriven(ActivityExecutionContext context, EventDrivenActivity eventDriven)
        { 
            Debug.Assert(IsEventDrivenSubscribed(eventDriven));
            IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven);
            UnsubscribeEventActivity(context, eventActivity);
        } 

        private StateMachineSubscription SubscribeEventActivity(ActivityExecutionContext context, 
            IEventActivity eventActivity) 
        {
            EventActivitySubscription subscription = new EventActivitySubscription(); 
            StateActivity state = (StateActivity)context.Activity;
            subscription.Subscribe(context, state, eventActivity);
            WorkflowQueue workflowQueue = GetWorkflowQueue(context, subscription.QueueName);
            if (workflowQueue != null) 
                workflowQueue.Enabled = true;
 
            Debug.Assert(subscription.QueueName != null); 
            this.Subscriptions[subscription.QueueName] = subscription;
 
            return subscription;
        }

        private void UnsubscribeEventActivity(ActivityExecutionContext context, 
            IEventActivity eventActivity)
        { 
            if (context == null) 
                throw new ArgumentNullException("context");
            if (eventActivity == null) 
                throw new ArgumentNullException("eventActivity");

            EventActivitySubscription subscription = GetSubscription(eventActivity);
            WorkflowQueue workflowQueue = GetWorkflowQueue(context, subscription.QueueName); 
            if (workflowQueue != null)
                workflowQueue.Enabled = false; 
            UnsubscribeEventActivity(context, eventActivity, subscription); 
        }
 
        private void UnsubscribeEventActivity(ActivityExecutionContext context,
            IEventActivity eventActivity,
            EventActivitySubscription subscription)
        { 
            if (context == null)
                throw new ArgumentNullException("context"); 
            if (eventActivity == null) 
                throw new ArgumentNullException("eventActivity");
            if (subscription == null) 
                throw new ArgumentNullException("subscription");

            subscription.Unsubscribe(context, eventActivity);
            RemoveFromQueue(subscription.SubscriptionId); 

            Debug.Assert(subscription.QueueName != null); 
            this.Subscriptions.Remove(subscription.QueueName); 
        }
 
        internal void CreateSetStateEventQueue(ActivityExecutionContext context)
        {
            this.SetStateSubscription.CreateQueue(context);
            this.Subscriptions[this.SetStateSubscription.SubscriptionId] = this.SetStateSubscription; 
        }
 
        internal void DeleteSetStateEventQueue(ActivityExecutionContext context) 
        {
            this.Subscriptions[this.SetStateSubscription.SubscriptionId] = null; 
            this.SetStateSubscription.DeleteQueue(context);
        }

        internal void SubscribeToSetStateEvent(ActivityExecutionContext context) 
        {
            this.SetStateSubscription.Subscribe(context); 
            this.Subscriptions[this.SetStateSubscription.SubscriptionId] = this.SetStateSubscription; 
        }
 
        internal void UnsubscribeToSetStateEvent(ActivityExecutionContext context)
        {
            this.Subscriptions[this.SetStateSubscription.SubscriptionId] = null;
            this.SetStateSubscription.Unsubscribe(context); 
        }
 
        private bool IsEventDrivenSubscribed(EventDrivenActivity eventDriven) 
        {
            IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven); 
            EventActivitySubscription subscription = GetSubscription(eventActivity);
            return (subscription != null);
        }
 
        private EventActivitySubscription GetSubscription(IEventActivity eventActivity)
        { 
            IComparable queueName = GetQueueName(eventActivity); 
            if ((queueName == null) || (!this.Subscriptions.ContainsKey(queueName)))
                return null; 

            EventActivitySubscription subscription = this.Subscriptions[queueName] as EventActivitySubscription;

            Activity activity = (Activity)eventActivity; 
            if (subscription == null ||
                subscription.EventActivityName != activity.QualifiedName) 
                return null; 

            return subscription; 
        }

        private StateMachineSubscription GetSubscription(IComparable queueName)
        { 
            StateMachineSubscription subscription;
            this.Subscriptions.TryGetValue(queueName, out subscription); 
            return subscription; 
        }
 
        /* Currently not used, left here for completeness
        internal static void EnableStateWorkflowQueues(ActivityExecutionContext context, StateActivity state)
        {
            ChangeStateWorkflowQueuesState(context, state, true); 
        }
        */ 
 
        internal static void DisableStateWorkflowQueues(ActivityExecutionContext context, StateActivity state)
        { 
            ChangeStateWorkflowQueuesState(context, state, false);
        }

        private static void ChangeStateWorkflowQueuesState(ActivityExecutionContext context, StateActivity state, bool enabled) 
        {
            foreach (Activity activity in state.EnabledActivities) 
            { 
                EventDrivenActivity eventDriven = activity as EventDrivenActivity;
                if (eventDriven != null) 
                    ChangeEventDrivenQueueState(context, eventDriven, enabled);
            }
        }
 
        internal static void ChangeEventDrivenQueueState(ActivityExecutionContext context, EventDrivenActivity eventDriven, bool enabled)
        { 
            IEventActivity eventActivity = StateMachineHelpers.GetEventActivity(eventDriven); 
            IComparable queueName = GetQueueName(eventActivity);
            if (queueName == null) 
                return; // skip unitialized follower
            WorkflowQueue workflowQueue = GetWorkflowQueue(context, queueName);
            if (workflowQueue != null)
                workflowQueue.Enabled = enabled; 
        }
 
        internal static WorkflowQueue GetWorkflowQueue(ActivityExecutionContext context, IComparable queueName) 
        {
            WorkflowQueuingService workflowQueuingService = context.GetService(); 
            if (workflowQueuingService.Exists(queueName))
            {
                WorkflowQueue workflowQueue = workflowQueuingService.GetWorkflowQueue(queueName);
                return workflowQueue; 
            }
            return null; 
        } 

        private static IComparable GetQueueName(IEventActivity eventActivity) 
        {
            IComparable queueName = eventActivity.QueueName;
            return queueName;
        } 

        private Dictionary GetSubscriptionsShallowCopy() 
        { 
            Dictionary subscriptions = new Dictionary();
            foreach (KeyValuePair dictionaryEntry in this.Subscriptions) 
            {
                subscriptions.Add(dictionaryEntry.Key, dictionaryEntry.Value);
            }
            return subscriptions; 
        }
 
        #region Event Queue Methods 

        internal void Enqueue(ActivityExecutionContext context, Guid subscriptionId) 
        {
            StateMachineSubscription subscription = GetSubscription(subscriptionId);
            if (subscription != null)
            { 
                // subscription can be null if we already unsubscribed to
                // this event 
                this.EventQueue.Add(subscription); 
            }
            ProcessQueue(context); 
        }

        internal void Enqueue(ActivityExecutionContext context, IComparable queueName)
        { 
            StateMachineSubscription subscription = GetSubscription(queueName);
            if (subscription != null) 
            { 
                // subscription can be null if we already unsubscribed to
                // this event 
                this.EventQueue.Add(subscription);
            }
            ProcessQueue(context);
        } 

        internal StateMachineSubscription Dequeue() 
        { 
            StateMachineSubscription subscription = this.EventQueue[0];
            this.EventQueue.RemoveAt(0); 
            return subscription;
        }

        private void RemoveFromQueue(Guid subscriptionId) 
        {
            this.EventQueue.RemoveAll(delegate(StateMachineSubscription subscription) { return subscription.SubscriptionId.Equals(subscriptionId); }); 
        } 

        internal void ProcessQueue(ActivityExecutionContext context) 
        {
            StateActivity currentState = StateMachineHelpers.GetCurrentState(context);
            if (this.EventQueue.Count == 0 ||
                this.ExecutionState.HasEnqueuedActions || 
                this.ExecutionState.SchedulerBusy ||
                currentState == null) 
                return; 

            StateMachineSubscription subscription = Dequeue(); 
            subscription.ProcessEvent(context);
        }

        #endregion Event Queue Methods 

    } 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
                        

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