Delay.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 / Delay.cs / 1305376 / Delay.cs

                            namespace System.Workflow.Activities 
{
    using System;
    using System.Text;
    using System.Reflection; 
    using System.Collections;
    using System.CodeDom; 
    using System.ComponentModel; 
    using System.ComponentModel.Design;
    using System.Drawing; 
    using System.Workflow.ComponentModel;
    using System.Workflow.ComponentModel.Design;
    using System.Collections.Generic;
    using System.Workflow.Runtime; 
    using System.Workflow.Runtime.Hosting;
    using System.Workflow.ComponentModel.Compiler; 
    using System.Diagnostics; 
    using System.Globalization;
    using System.Workflow.Activities.Common; 

    [SRDescription(SR.DelayActivityDescription)]
    [ToolboxItem(typeof(ActivityToolboxItem))]
    [Designer(typeof(DelayDesigner), typeof(IDesigner))] 
    [ToolboxBitmap(typeof(DelayActivity), "Resources.Delay.png")]
    [DefaultEvent("InitializeTimeoutDuration")] 
    [ActivityValidator(typeof(DelayActivityValidator))] 
    [SRCategory(SR.Standard)]
    public sealed class DelayActivity : Activity, IEventActivity, IActivityEventListener 
    {
        #region Public Dependency Properties
        public static readonly DependencyProperty InitializeTimeoutDurationEvent = DependencyProperty.Register("InitializeTimeoutDuration", typeof(EventHandler), typeof(DelayActivity));
        public static readonly DependencyProperty TimeoutDurationProperty = DependencyProperty.Register("TimeoutDuration", typeof(TimeSpan), typeof(DelayActivity), new PropertyMetadata(new TimeSpan(0, 0, 0))); 
        #endregion
        #region Private Dependency Properties 
        private static readonly DependencyProperty QueueNameProperty = DependencyProperty.Register("QueueName", typeof(IComparable), typeof(DelayActivity)); 
        #endregion
 
        #region Constructors

        public DelayActivity()
        { 
        }
 
        public DelayActivity(string name) 
            : base(name)
        { 
        }

        #endregion
 
        #region Public Handlers
        [SRCategory(SR.Handlers)] 
        [SRDescription(SR.TimeoutInitializerDescription)] 
        [MergableProperty(false)]
        public event EventHandler InitializeTimeoutDuration 
        {
            add
            {
                base.AddHandler(InitializeTimeoutDurationEvent, value); 
            }
            remove 
            { 
                base.RemoveHandler(InitializeTimeoutDurationEvent, value);
            } 
        }
        #endregion

        #region Public Properties 
        [SRDescription(SR.TimeoutDurationDescription)]
        [MergableProperty(false)] 
        [TypeConverter(typeof(TimeoutDurationConverter))] 
        public TimeSpan TimeoutDuration
        { 
            get
            {
                return (TimeSpan)base.GetValue(TimeoutDurationProperty);
            } 
            set
            { 
                base.SetValue(TimeoutDurationProperty, value); 
            }
        } 
        #endregion

        #region Protected Methods
 
        protected override void Initialize(IServiceProvider provider)
        { 
            base.Initialize(provider); 

            // Define the queue name for this Delay 
            this.SetValue(QueueNameProperty, Guid.NewGuid());
        }

        protected override ActivityExecutionStatus Execute(ActivityExecutionContext executionContext) 
        {
            if (executionContext == null) 
                throw new ArgumentNullException("executionContext"); 

            if (this.IsInEventActivityMode) 
            {
                return ActivityExecutionStatus.Closed;
            }
            else 
            {
                ((IEventActivity)this).Subscribe(executionContext, this); 
                this.IsInEventActivityMode = false; 
                return ActivityExecutionStatus.Executing;
            } 
        }

        protected override ActivityExecutionStatus Cancel(ActivityExecutionContext executionContext)
        { 
            if (executionContext == null)
                throw new ArgumentNullException("executionContext"); 
 
            if (!this.IsInEventActivityMode)
            { 
                if (this.SubscriptionID != Guid.Empty)
                {
                    ((IEventActivity)this).Unsubscribe(executionContext, this);
                } 
            }
            return ActivityExecutionStatus.Closed; 
        } 

        protected sealed override ActivityExecutionStatus HandleFault(ActivityExecutionContext executionContext, Exception exception) 
        {
            if (executionContext == null)
                throw new ArgumentNullException("executionContext");
 
            if (exception == null)
                throw new ArgumentNullException("exception"); 
 
            ActivityExecutionStatus newStatus = this.Cancel(executionContext);
            if (newStatus == ActivityExecutionStatus.Canceling) 
                return ActivityExecutionStatus.Faulting;

            return newStatus;
        } 

        protected override void OnClosed(IServiceProvider provider) 
        { 
            base.RemoveProperty(DelayActivity.SubscriptionIDProperty);
            base.RemoveProperty(DelayActivity.IsInEventActivityModeProperty); 
        }

        private class DelayActivityValidator : ActivityValidator
        { 
            public override ValidationErrorCollection Validate(ValidationManager manager, object obj)
            { 
                ValidationErrorCollection errors = new ValidationErrorCollection(); 

                DelayActivity delay = obj as DelayActivity; 
                if (delay == null)
                    throw new InvalidOperationException();

                if (delay.TimeoutDuration.Ticks < 0) 
                {
                    errors.Add(new ValidationError(SR.GetString(SR.Error_NegativeValue, new object[] { delay.TimeoutDuration.ToString(), "TimeoutDuration" }), ErrorNumbers.Error_NegativeValue)); 
                } 

                errors.AddRange(base.Validate(manager, obj)); 
                return errors;
            }
        }
        #endregion 

        #region Private Implementation 
        #region Runtime Data / Properties 
        static DependencyProperty SubscriptionIDProperty = DependencyProperty.Register("SubscriptionID", typeof(Guid), typeof(DelayActivity), new PropertyMetadata(Guid.NewGuid()));
        static DependencyProperty IsInEventActivityModeProperty = DependencyProperty.Register("IsInEventActivityMode", typeof(bool), typeof(DelayActivity), new PropertyMetadata(false)); 

        private Guid SubscriptionID
        {
            get 
            {
                return (Guid)base.GetValue(DelayActivity.SubscriptionIDProperty); 
            } 
            set
            { 
                base.SetValue(DelayActivity.SubscriptionIDProperty, value);
            }
        }
        private bool IsInEventActivityMode 
        {
            get 
            { 
                return (bool)base.GetValue(DelayActivity.IsInEventActivityModeProperty);
            } 
            set
            {
                base.SetValue(DelayActivity.IsInEventActivityModeProperty, value);
            } 
        }
        #endregion 
 
        #region Timeout Duration Conversion Helper
        private sealed class TimeoutDurationConverter : TypeConverter 
        {
            public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
            {
                if (destinationType == typeof(string)) 
                    return true;
 
                return base.CanConvertTo(context, destinationType); 
            }
 
            public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
            {
                if (destinationType == typeof(string) && value is TimeSpan)
                { 
                    TimeSpan timespan = (TimeSpan)value;
                    return timespan.ToString(); 
                } 

                return base.ConvertTo(context, culture, value, destinationType); 
            }

            public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
            { 
                if (sourceType == typeof(string))
                    return true; 
 
                return base.CanConvertFrom(context, sourceType);
            } 

            public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
            {
                object parsedTimespan = TimeSpan.Zero; 
                string timeSpan = value as string;
                if (!String.IsNullOrEmpty(timeSpan)) 
                { 
                    //If this fails then an exception is thrown and the property set would fail
                    try 
                    {
                        parsedTimespan = TimeSpan.Parse(timeSpan, CultureInfo.InvariantCulture);
                        if (parsedTimespan != null && ((TimeSpan)parsedTimespan).Ticks < 0)
                            throw new Exception(string.Format(System.Globalization.CultureInfo.CurrentCulture, SR.GetString(SR.Error_NegativeValue), value.ToString(), "TimeoutDuration")); 
                    }
                    catch 
                    { 
                        throw new Exception(SR.GetString(SR.InvalidTimespanFormat, timeSpan));
                    } 
                }

                return parsedTimespan;
            } 

            public override bool GetStandardValuesSupported(ITypeDescriptorContext context) 
            { 
                return true;
            } 

            public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
            {
                ArrayList standardValuesCollection = new ArrayList(); 
                standardValuesCollection.Add(new TimeSpan(0, 0, 0));
                standardValuesCollection.Add(new TimeSpan(0, 1, 0)); 
                standardValuesCollection.Add(new TimeSpan(0, 30, 0)); 
                standardValuesCollection.Add(new TimeSpan(1, 0, 0));
                standardValuesCollection.Add(new TimeSpan(12, 0, 0)); 
                standardValuesCollection.Add(new TimeSpan(1, 0, 0, 0));

                return new StandardValuesCollection(standardValuesCollection);
            } 
        }
        #endregion 
        #endregion 

        #region IActivityEventListener Implementation 
        void IActivityEventListener.OnEvent(object sender, QueueEventArgs e)
        {
            if (sender == null)
                throw new ArgumentNullException("sender"); 
            if (e == null)
                throw new ArgumentNullException("e"); 
 
            ActivityExecutionContext context = sender as ActivityExecutionContext;
 
            if (context == null)
                throw new ArgumentException(SR.Error_SenderMustBeActivityExecutionContext, "sender");

            if (this.ExecutionStatus != ActivityExecutionStatus.Closed) 
            {
                System.Diagnostics.Debug.Assert(this.SubscriptionID != Guid.Empty); 
 
                WorkflowQueuingService qService = context.GetService();
                qService.GetWorkflowQueue(e.QueueName).Dequeue(); 
                qService.DeleteWorkflowQueue(e.QueueName);
                context.CloseActivity();
            }
        } 
        #endregion
 
        #region IEventActivity implementation 
        void IEventActivity.Subscribe(ActivityExecutionContext parentContext, IActivityEventListener parentEventHandler)
        { 
            if (parentContext == null)
                throw new ArgumentNullException("parentContext");
            if (parentEventHandler == null)
                throw new ArgumentNullException("parentEventHandler"); 

            this.IsInEventActivityMode = true; 
 
            base.RaiseEvent(DelayActivity.InitializeTimeoutDurationEvent, this, EventArgs.Empty);
            TimeSpan timeSpan = this.TimeoutDuration; 
            DateTime timeOut = DateTime.UtcNow + timeSpan;

            WorkflowQueuingService qService = parentContext.GetService();
 
            IComparable queueName = ((IEventActivity)this).QueueName;
            TimerEventSubscription timerSub = new TimerEventSubscription((Guid)queueName, this.WorkflowInstanceId, timeOut); 
            WorkflowQueue queue = qService.CreateWorkflowQueue(queueName, false); 

            queue.RegisterForQueueItemAvailable(parentEventHandler, this.QualifiedName); 
            this.SubscriptionID = timerSub.SubscriptionId;

            Activity root = this;
            while (root.Parent != null) 
                root = root.Parent;
 
            TimerEventSubscriptionCollection timers = (TimerEventSubscriptionCollection)root.GetValue(TimerEventSubscriptionCollection.TimerCollectionProperty); 
            Debug.Assert(timers != null, "TimerEventSubscriptionCollection on root activity should never be null, but it was");
            timers.Add(timerSub); 
        }

        void IEventActivity.Unsubscribe(ActivityExecutionContext parentContext, IActivityEventListener parentEventHandler)
        { 
            if (parentContext == null)
                throw new ArgumentNullException("parentContext"); 
            if (parentEventHandler == null) 
                throw new ArgumentNullException("parentEventHandler");
 
            System.Diagnostics.Debug.Assert(this.SubscriptionID != Guid.Empty);
            WorkflowQueuingService qService = parentContext.GetService();
            WorkflowQueue wfQueue = null;
 
            try
            { 
                wfQueue = qService.GetWorkflowQueue(this.SubscriptionID); 
            }
            catch 
            {
                // If the queue no longer exists, eat the exception, we clear the subscription id later.
            }
 
            if (wfQueue != null && wfQueue.Count != 0)
                wfQueue.Dequeue(); 
 
            // WinOE Bug 16929: In the case of dynamic update, if this activity is being removed,
            // we can not trace back to the root activity from "this". 
            Activity root = parentContext.Activity;
            while (root.Parent != null)
                root = root.Parent;
            TimerEventSubscriptionCollection timers = (TimerEventSubscriptionCollection)root.GetValue(TimerEventSubscriptionCollection.TimerCollectionProperty); 
            Debug.Assert(timers != null, "TimerEventSubscriptionCollection on root activity should never be null, but it was");
            timers.Remove(this.SubscriptionID); 
 
            if (wfQueue != null)
            { 
                wfQueue.UnregisterForQueueItemAvailable(parentEventHandler);
                qService.DeleteWorkflowQueue(this.SubscriptionID);
            }
 
            this.SubscriptionID = Guid.Empty;
        } 
 
        IComparable IEventActivity.QueueName
        { 
            get
            {
                return (IComparable)this.GetValue(QueueNameProperty);
            } 
        }
 
        #endregion 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
namespace System.Workflow.Activities 
{
    using System;
    using System.Text;
    using System.Reflection; 
    using System.Collections;
    using System.CodeDom; 
    using System.ComponentModel; 
    using System.ComponentModel.Design;
    using System.Drawing; 
    using System.Workflow.ComponentModel;
    using System.Workflow.ComponentModel.Design;
    using System.Collections.Generic;
    using System.Workflow.Runtime; 
    using System.Workflow.Runtime.Hosting;
    using System.Workflow.ComponentModel.Compiler; 
    using System.Diagnostics; 
    using System.Globalization;
    using System.Workflow.Activities.Common; 

    [SRDescription(SR.DelayActivityDescription)]
    [ToolboxItem(typeof(ActivityToolboxItem))]
    [Designer(typeof(DelayDesigner), typeof(IDesigner))] 
    [ToolboxBitmap(typeof(DelayActivity), "Resources.Delay.png")]
    [DefaultEvent("InitializeTimeoutDuration")] 
    [ActivityValidator(typeof(DelayActivityValidator))] 
    [SRCategory(SR.Standard)]
    public sealed class DelayActivity : Activity, IEventActivity, IActivityEventListener 
    {
        #region Public Dependency Properties
        public static readonly DependencyProperty InitializeTimeoutDurationEvent = DependencyProperty.Register("InitializeTimeoutDuration", typeof(EventHandler), typeof(DelayActivity));
        public static readonly DependencyProperty TimeoutDurationProperty = DependencyProperty.Register("TimeoutDuration", typeof(TimeSpan), typeof(DelayActivity), new PropertyMetadata(new TimeSpan(0, 0, 0))); 
        #endregion
        #region Private Dependency Properties 
        private static readonly DependencyProperty QueueNameProperty = DependencyProperty.Register("QueueName", typeof(IComparable), typeof(DelayActivity)); 
        #endregion
 
        #region Constructors

        public DelayActivity()
        { 
        }
 
        public DelayActivity(string name) 
            : base(name)
        { 
        }

        #endregion
 
        #region Public Handlers
        [SRCategory(SR.Handlers)] 
        [SRDescription(SR.TimeoutInitializerDescription)] 
        [MergableProperty(false)]
        public event EventHandler InitializeTimeoutDuration 
        {
            add
            {
                base.AddHandler(InitializeTimeoutDurationEvent, value); 
            }
            remove 
            { 
                base.RemoveHandler(InitializeTimeoutDurationEvent, value);
            } 
        }
        #endregion

        #region Public Properties 
        [SRDescription(SR.TimeoutDurationDescription)]
        [MergableProperty(false)] 
        [TypeConverter(typeof(TimeoutDurationConverter))] 
        public TimeSpan TimeoutDuration
        { 
            get
            {
                return (TimeSpan)base.GetValue(TimeoutDurationProperty);
            } 
            set
            { 
                base.SetValue(TimeoutDurationProperty, value); 
            }
        } 
        #endregion

        #region Protected Methods
 
        protected override void Initialize(IServiceProvider provider)
        { 
            base.Initialize(provider); 

            // Define the queue name for this Delay 
            this.SetValue(QueueNameProperty, Guid.NewGuid());
        }

        protected override ActivityExecutionStatus Execute(ActivityExecutionContext executionContext) 
        {
            if (executionContext == null) 
                throw new ArgumentNullException("executionContext"); 

            if (this.IsInEventActivityMode) 
            {
                return ActivityExecutionStatus.Closed;
            }
            else 
            {
                ((IEventActivity)this).Subscribe(executionContext, this); 
                this.IsInEventActivityMode = false; 
                return ActivityExecutionStatus.Executing;
            } 
        }

        protected override ActivityExecutionStatus Cancel(ActivityExecutionContext executionContext)
        { 
            if (executionContext == null)
                throw new ArgumentNullException("executionContext"); 
 
            if (!this.IsInEventActivityMode)
            { 
                if (this.SubscriptionID != Guid.Empty)
                {
                    ((IEventActivity)this).Unsubscribe(executionContext, this);
                } 
            }
            return ActivityExecutionStatus.Closed; 
        } 

        protected sealed override ActivityExecutionStatus HandleFault(ActivityExecutionContext executionContext, Exception exception) 
        {
            if (executionContext == null)
                throw new ArgumentNullException("executionContext");
 
            if (exception == null)
                throw new ArgumentNullException("exception"); 
 
            ActivityExecutionStatus newStatus = this.Cancel(executionContext);
            if (newStatus == ActivityExecutionStatus.Canceling) 
                return ActivityExecutionStatus.Faulting;

            return newStatus;
        } 

        protected override void OnClosed(IServiceProvider provider) 
        { 
            base.RemoveProperty(DelayActivity.SubscriptionIDProperty);
            base.RemoveProperty(DelayActivity.IsInEventActivityModeProperty); 
        }

        private class DelayActivityValidator : ActivityValidator
        { 
            public override ValidationErrorCollection Validate(ValidationManager manager, object obj)
            { 
                ValidationErrorCollection errors = new ValidationErrorCollection(); 

                DelayActivity delay = obj as DelayActivity; 
                if (delay == null)
                    throw new InvalidOperationException();

                if (delay.TimeoutDuration.Ticks < 0) 
                {
                    errors.Add(new ValidationError(SR.GetString(SR.Error_NegativeValue, new object[] { delay.TimeoutDuration.ToString(), "TimeoutDuration" }), ErrorNumbers.Error_NegativeValue)); 
                } 

                errors.AddRange(base.Validate(manager, obj)); 
                return errors;
            }
        }
        #endregion 

        #region Private Implementation 
        #region Runtime Data / Properties 
        static DependencyProperty SubscriptionIDProperty = DependencyProperty.Register("SubscriptionID", typeof(Guid), typeof(DelayActivity), new PropertyMetadata(Guid.NewGuid()));
        static DependencyProperty IsInEventActivityModeProperty = DependencyProperty.Register("IsInEventActivityMode", typeof(bool), typeof(DelayActivity), new PropertyMetadata(false)); 

        private Guid SubscriptionID
        {
            get 
            {
                return (Guid)base.GetValue(DelayActivity.SubscriptionIDProperty); 
            } 
            set
            { 
                base.SetValue(DelayActivity.SubscriptionIDProperty, value);
            }
        }
        private bool IsInEventActivityMode 
        {
            get 
            { 
                return (bool)base.GetValue(DelayActivity.IsInEventActivityModeProperty);
            } 
            set
            {
                base.SetValue(DelayActivity.IsInEventActivityModeProperty, value);
            } 
        }
        #endregion 
 
        #region Timeout Duration Conversion Helper
        private sealed class TimeoutDurationConverter : TypeConverter 
        {
            public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
            {
                if (destinationType == typeof(string)) 
                    return true;
 
                return base.CanConvertTo(context, destinationType); 
            }
 
            public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
            {
                if (destinationType == typeof(string) && value is TimeSpan)
                { 
                    TimeSpan timespan = (TimeSpan)value;
                    return timespan.ToString(); 
                } 

                return base.ConvertTo(context, culture, value, destinationType); 
            }

            public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
            { 
                if (sourceType == typeof(string))
                    return true; 
 
                return base.CanConvertFrom(context, sourceType);
            } 

            public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
            {
                object parsedTimespan = TimeSpan.Zero; 
                string timeSpan = value as string;
                if (!String.IsNullOrEmpty(timeSpan)) 
                { 
                    //If this fails then an exception is thrown and the property set would fail
                    try 
                    {
                        parsedTimespan = TimeSpan.Parse(timeSpan, CultureInfo.InvariantCulture);
                        if (parsedTimespan != null && ((TimeSpan)parsedTimespan).Ticks < 0)
                            throw new Exception(string.Format(System.Globalization.CultureInfo.CurrentCulture, SR.GetString(SR.Error_NegativeValue), value.ToString(), "TimeoutDuration")); 
                    }
                    catch 
                    { 
                        throw new Exception(SR.GetString(SR.InvalidTimespanFormat, timeSpan));
                    } 
                }

                return parsedTimespan;
            } 

            public override bool GetStandardValuesSupported(ITypeDescriptorContext context) 
            { 
                return true;
            } 

            public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
            {
                ArrayList standardValuesCollection = new ArrayList(); 
                standardValuesCollection.Add(new TimeSpan(0, 0, 0));
                standardValuesCollection.Add(new TimeSpan(0, 1, 0)); 
                standardValuesCollection.Add(new TimeSpan(0, 30, 0)); 
                standardValuesCollection.Add(new TimeSpan(1, 0, 0));
                standardValuesCollection.Add(new TimeSpan(12, 0, 0)); 
                standardValuesCollection.Add(new TimeSpan(1, 0, 0, 0));

                return new StandardValuesCollection(standardValuesCollection);
            } 
        }
        #endregion 
        #endregion 

        #region IActivityEventListener Implementation 
        void IActivityEventListener.OnEvent(object sender, QueueEventArgs e)
        {
            if (sender == null)
                throw new ArgumentNullException("sender"); 
            if (e == null)
                throw new ArgumentNullException("e"); 
 
            ActivityExecutionContext context = sender as ActivityExecutionContext;
 
            if (context == null)
                throw new ArgumentException(SR.Error_SenderMustBeActivityExecutionContext, "sender");

            if (this.ExecutionStatus != ActivityExecutionStatus.Closed) 
            {
                System.Diagnostics.Debug.Assert(this.SubscriptionID != Guid.Empty); 
 
                WorkflowQueuingService qService = context.GetService();
                qService.GetWorkflowQueue(e.QueueName).Dequeue(); 
                qService.DeleteWorkflowQueue(e.QueueName);
                context.CloseActivity();
            }
        } 
        #endregion
 
        #region IEventActivity implementation 
        void IEventActivity.Subscribe(ActivityExecutionContext parentContext, IActivityEventListener parentEventHandler)
        { 
            if (parentContext == null)
                throw new ArgumentNullException("parentContext");
            if (parentEventHandler == null)
                throw new ArgumentNullException("parentEventHandler"); 

            this.IsInEventActivityMode = true; 
 
            base.RaiseEvent(DelayActivity.InitializeTimeoutDurationEvent, this, EventArgs.Empty);
            TimeSpan timeSpan = this.TimeoutDuration; 
            DateTime timeOut = DateTime.UtcNow + timeSpan;

            WorkflowQueuingService qService = parentContext.GetService();
 
            IComparable queueName = ((IEventActivity)this).QueueName;
            TimerEventSubscription timerSub = new TimerEventSubscription((Guid)queueName, this.WorkflowInstanceId, timeOut); 
            WorkflowQueue queue = qService.CreateWorkflowQueue(queueName, false); 

            queue.RegisterForQueueItemAvailable(parentEventHandler, this.QualifiedName); 
            this.SubscriptionID = timerSub.SubscriptionId;

            Activity root = this;
            while (root.Parent != null) 
                root = root.Parent;
 
            TimerEventSubscriptionCollection timers = (TimerEventSubscriptionCollection)root.GetValue(TimerEventSubscriptionCollection.TimerCollectionProperty); 
            Debug.Assert(timers != null, "TimerEventSubscriptionCollection on root activity should never be null, but it was");
            timers.Add(timerSub); 
        }

        void IEventActivity.Unsubscribe(ActivityExecutionContext parentContext, IActivityEventListener parentEventHandler)
        { 
            if (parentContext == null)
                throw new ArgumentNullException("parentContext"); 
            if (parentEventHandler == null) 
                throw new ArgumentNullException("parentEventHandler");
 
            System.Diagnostics.Debug.Assert(this.SubscriptionID != Guid.Empty);
            WorkflowQueuingService qService = parentContext.GetService();
            WorkflowQueue wfQueue = null;
 
            try
            { 
                wfQueue = qService.GetWorkflowQueue(this.SubscriptionID); 
            }
            catch 
            {
                // If the queue no longer exists, eat the exception, we clear the subscription id later.
            }
 
            if (wfQueue != null && wfQueue.Count != 0)
                wfQueue.Dequeue(); 
 
            // WinOE Bug 16929: In the case of dynamic update, if this activity is being removed,
            // we can not trace back to the root activity from "this". 
            Activity root = parentContext.Activity;
            while (root.Parent != null)
                root = root.Parent;
            TimerEventSubscriptionCollection timers = (TimerEventSubscriptionCollection)root.GetValue(TimerEventSubscriptionCollection.TimerCollectionProperty); 
            Debug.Assert(timers != null, "TimerEventSubscriptionCollection on root activity should never be null, but it was");
            timers.Remove(this.SubscriptionID); 
 
            if (wfQueue != null)
            { 
                wfQueue.UnregisterForQueueItemAvailable(parentEventHandler);
                qService.DeleteWorkflowQueue(this.SubscriptionID);
            }
 
            this.SubscriptionID = Guid.Empty;
        } 
 
        IComparable IEventActivity.QueueName
        { 
            get
            {
                return (IComparable)this.GetValue(QueueNameProperty);
            } 
        }
 
        #endregion 
    }
} 

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

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