Introduction: The InvokeMethod activity is another way to implement a code which is outside of the standard built-in activities. You can use this activity to invoke a method of a class. The class does not need to be part of the workflow or use any of the workflow base classes. The InvokeMethod calls a public method of a specified object or type.

InvokeMethod Properties:

InvokeMethod Class:

Namespace: System.Activities.Statements.
Assembly: System.Activities (in System.Activities.dll).

Step 1: Open Visual Studio 2010.

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Define Arguments:

Step 2: Go to the Workflow.xaml file and double-click on the Arguments option.

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Step 3: Drag Activity from Toolbox.

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Step 4: Select Sequence and While activity and create variables.

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Step 5: Drag Sequence, Assign, InvokeMethod activity inside the body of While activity.

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Step 6: Go to properties of InvokeMethod and define MethodName, TargetObject.

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Step 7: Define Parameters for InvokeMethod.

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Step 8: Go to the Programe.cs file and write the below code.


using System;
 using System.Linq;
 using System.Activities;
 using System.Activities.Statements;
 using System.Activities.Expressions;
 using System.Collections.Generic;
 using System.ServiceModel.Activities;
 using System.Runtime.Serialization;
 using System.Collections;
 namespace WorkflowConsoleApplication23
{
class Program
 {
static void Main(string[] args)
{
Console.Write("Enter string: ");
string reversedString = string.Empty;
IDictionary<string, object> results = WorkflowInvoker.Invoke(new ReverseStringWorkflow(),
new Dictionary<string, object>{ {"StringToReverse", stringToReverse } });
 Console.Write("Reversed string: ");
 Console.WriteLine(results["ReversedString"]);
 Console.ReadKey();
}
}
}

Creating Workflow using code:

Step 9: Write the code for creation of Workflow.

class.gif

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Activities;
using System.Activities.Expressions;
using System.Activities.Statements;
using System.ComponentModel;
using System.Runtime.Serialization;

namespace WorkflowConsoleApplication23
{
 class Class1
 {
 public class ReverseStringWorkflow : Activit
 {
 public InArgument<string> StringToReverse { get; set; }
 public OutArgument<string> ReversedString { get; set; }
 protected override Func<Activity> Implementation
 {
 get
 {
 return () =>
 {
 Sequence sequence = new Sequence
 {
 Variables = new Variable<StringBuilder>("ReverseStringBuilder", new StringBuilder())},
 Activities = new While
 {
 Variables = new Variable<int>("Counter")
 {
 Default = new VisualBasicValue<int>("StringToReverse.Length")
 }
 },
 Condition = new VisualBasicValue<bool>("Counter > 0"),
 Body = new Sequence
 {
 Activities =
 {
 new Assign
 {
 To = new OutArgument<int>(new VisualBasicReference<int>("Counter")),
 Value = new InArgument<int>(new VisualBasicValue<int>("Counter - 1"))
 },
 new InvokeMethod
 {
 MethodName = "Append",
 TargetObject = new InArgument<StringBuilder>(new VisualBasicValue<StringBuilder>("ReverseStringBuilder")),
 Parameters =
 {
 new InArgument<char>(new VisualBasicValue<char>("StringToReverse.Chars(Counter)"))
 }
 }
 }
 }
 },
 new Assign|
 {
 To = new OutArgument<string>(new VisualBasicReference<string>("ReversedString")),
 Value = new InArgument<string>(new VisualBasicValue<string>("ReverseStringBuilder.ToString()"))
 }
 }
 };
 return sequence;
 };
 }
 set
 {
 base.Implementation = value;
 }
 }
}

Step 10: Press F5 to run the application.

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