Sequential Workflow - Part 2

2009-09-28T11:29:29.82

partial class ATMSimulator
{
      #region Designer generated code

      ///  
      /// Required method for Designer support - do not modify 
      /// the contents of this method with the code editor.
      /// 
      [System.Diagnostics.DebuggerNonUserCode]
      private void InitializeComponent()
      {
          this.CanModifyActivities = true;
          System.Workflow.Activities.CodeCondition codecondition1 = new System.Workflow.Activities.CodeCondition();
          this.DispatchAmount = new System.Workflow.Activities.CodeActivity();
          this.GatherAmountInput = new System.Workflow.Activities.CodeActivity();
          this.CashWithdrawalSequence = new System.Workflow.Activities.SequenceActivity();
          this.WhileUserNeedsATMService = new System.Workflow.Activities.WhileActivity();
          // 
          // DispatchAmount
          // 
          this.DispatchAmount.Name = "DispatchAmount";
          this.DispatchAmount.ExecuteCode += new System.EventHandler(this.DispatchAmount_ExecuteCode);
          // 
          // GatherAmountInput
          // 
          this.GatherAmountInput.Name = "GatherAmountInput";
          this.GatherAmountInput.ExecuteCode += new System.EventHandler(this.GatherAmountInput_ExecuteCode);
          // 
          // CashWithdrawalSequence
          // 
          this.CashWithdrawalSequence.Activities.Add(this.GatherAmountInput); 3
          this.CashWithdrawalSequence.Activities.Add(this.DispatchAmount);
          this.CashWithdrawalSequence.Name = "CashWithdrawalSequence";
          // 
          // WhileUserNeedsATMService
          // 
          this.WhileUserNeedsATMService.Activities.Add(this.CashWithdrawalSequence);2
          codecondition1.Condition += new System.EventHandler  ( his.CheckUserNeedsATMService);
          this.WhileUserNeedsATMService.Condition = codecondition1; 4
          this.WhileUserNeedsATMService.Name = "WhileUserNeedsATMService";
          // 
          // ATMSimulator
          // 
          this.Activities.Add(this.WhileUserNeedsATMService);
          this.Name = "ATMSimulator";
          this.CanModifyActivities = false;

      }

      #endregion

      private CodeActivity DispatchAmount;
      private SequenceActivity CashWithdrawalSequence;
      private WhileActivity WhileUserNeedsATMService; 1
      private CodeActivity GatherAmountInput;

}

The major differnce from the Part 1 in this workflow is the inclusion of WhileActivity 1 so that the user can make more than one transaction in one go. WhileActivity is a CompositeActivity so it can conatin other activities 2. Since WhileActivity can execute only single activity, the previous activities are packaged in to a single SequenceActivity 3 and given to the WhileActivity 2. The Condition property of WhileActivity, which is set to an instance of CodeCondition 4 in this code, determines whether the WhileActivity should proceed or halt.

public sealed partial class ATMSimulator : SequentialWorkflowActivity
{
      private int amountToWithdraw = 0;
      private bool userNeedsService = true;

      public ATMSimulator()
      {
          InitializeComponent();
      }
      private void GatherAmountInput_ExecuteCode(object sender, EventArgs e) 1
      {
          Console.WriteLine("please sepecify the amount to withdraw");
          amountToWithdraw = int.Parse(Console.ReadLine());
      }

      private void DispatchAmount_ExecuteCode(object sender, EventArgs e) 2
      {
          Console.WriteLine(String.Format("Please collect {0:c} from the ATM", amountToWithdraw));
          Console.WriteLine("Enter Q to quit");
          userNeedsService = !Console.ReadLine().Equals("Q", StringComparison.OrdinalIgnoreCase); 3
       }

      private void CheckUserNeedsATMService(object sender, ConditionalEventArgs e) 4
      {
          e.Result = userNeedsService; 5
      }


}

The sequence activities are executed 1 2 in the first go and sets whether the user needs to do further transactions 3. Based on the user's preference, CodeCondition event handler 4 sets the Result to a boolean value to signal whether the while loop should halt or proceed 5.

Sequential Workflow - Part 1

2009-09-28T12:32:21.18

public sealed partial class ATMSimulator : SequentialWorkflowActivity 1
{
      private int amountToWithdraw = 0;
      public ATMSimulator()
      {
          InitializeComponent();
      }

      private void GatherAmountInput_ExecuteCode(object sender, EventArgs e)2
      {
          Console.WriteLine("please sepecify the amount to withdraw");
          amountToWithdraw = int.Parse(Console.ReadLine());
      }

      private void DispatchAmount_ExecuteCode(object sender, EventArgs e)3
      {
          Console.WriteLine(String.Format("Please collect {0:c} from the ATM", amountToWithdraw));
      }

}

Activities are the primary building blocks in Windows Workflow Foundation (WF) and the sequential workflow itself is an activity called SequentialWorkflowActivity 1. As the SequentialWorkflowActivity inherits from the CompositeActivity, it can execute the code in the child activities 2 3 in a forward-only direction.

partial class ATMSimulator
{
      #region Designer generated code

      ///  
      /// Required method for Designer support - do not modify 
      /// the contents of this method with the code editor.
      /// 
      [System.Diagnostics.DebuggerNonUserCode]
      private void InitializeComponent()
      {
          this.CanModifyActivities = true;
          this.DispatchAmount = new System.Workflow.Activities.CodeActivity();
          this.GatherAmountInput = new System.Workflow.Activities.CodeActivity();
          // 
          // DispatchAmount
          // 
          this.DispatchAmount.Name = "DispatchAmount";
          this.DispatchAmount.ExecuteCode += new System.EventHandler(this.DispatchAmount_ExecuteCode);
          // 
          // GatherAmountInput
          // 
          this.GatherAmountInput.Name = "GatherAmountInput";
          this.GatherAmountInput.ExecuteCode += new System.EventHandler(this.GatherAmountInput_ExecuteCode);
          // 
          // ATMSimulator
          // 
          this.Activities.Add(this.GatherAmountInput);
          this.Activities.Add(this.DispatchAmount);
          this.Name = "ATMSimulator";
          this.CanModifyActivities = false;

      }

      #endregion

      private CodeActivity DispatchAmount; 4
      private CodeActivity GatherAmountInput; 5

}

In the designer generated file of the simulator program there exists two code activities 4 5. The primary goal of the code activities are to invoke the code-beside methods 2 3. These methods will be used to examine and change the workflow instance states.

wf - on code

Sequential Workflow - Part 2

Sequential Workflow - Part 1