Creating a CustomActivity in Workflow

Introduction : In this article we will create Custom Activity in Workflow. The Custom Activity is default base activity and handle common functionality like dragging and dropping of child elements, deletion, selection, and addition. Custom activity in workflow is same concept as custom control in .NET applications.

Types of Custom Activity :

Custom activity that encapsulates a discrete task.
Custom composite activity that groups a collection of lower-level activities into a higher-level activity.

Namespace :

System.Workflow.ComponentModel.Activity.
System.Workflow.ComponentModel.CompositeActivity.

The Custom Activity is made up of four components :

Designer.
Validator.
Executor.
Toolbox.

Step 1 : Go to Visual Studio 2010.

Select File->New-> Project.
Select Sequential Workflow.

Step 2 : Go to Solution option and right-click.

Select Add -> New Item.
Select Workflow Activity Library.

Step 3 : We set the Base Class of Custom Activity.

Click Activity->Property window.
Select Base Class.

After you define the Base Class, Activity show look like this.

Step 4 : Go to Code view and write the below code.

Activity->View Code.
Write the below code.

Code :

using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Collections;
using System.Linq;
using System.Workflow.ComponentModel.Compiler;
using System.Workflow.ComponentModel.Serialization;
using System.Workflow.ComponentModel;
using System.Workflow.ComponentModel.Design;
using System.Workflow.Runtime;
using System.Workflow.Activities;
using System.Workflow.Activities.Rules;
namespace ActivityLibrary1
{
public partial class Activity1 : System.Workflow.ComponentModel.Activity
{
public Activity1()
{
InitializeComponent();
}
public static DependencyProperty FilePathProperty = System.Workflow.ComponentModel.DependencyProperty.Register("FilePath", typeof(string),typeof(Activity1));
[Description("FilePath")]
[Category("Activity1")]
[Browsable(true)]|
[DefaultValueAttribute("False")]|
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
public string FilePath
{
get
{
return ((string)base.GetValue(Activity1.FilePathProperty));
}
set
{
base.SetValue(Activity1.FilePathProperty, value)
}
}
}
}

Step 5 : Now we add the Activity in Toolbox.

Right-click in Toolbox.
Select "Choose Item".
Click on Browse tab.

Step 6 : We select CustomLibrary.dll from the custom activity project.

Step 7 : Now we can see in Toolbox the CustomActivity1 was created.

Step 8 : Go to Workflow1.cs Design option.

We can easily Drag the CustomActivity1 below the SequentialWorkflow.