Now that features of .NET 4.0 have started becoming officially public… I am also happy to start blogging about them.
Based on the available info.. here is the link containing the new features coming out in .NET framework 4.0.
What’s new in .net framework 4.0
I will be updating this link on regular basis .. so bookmark it.
In this post i will demonstrate how to build a basic state machine workflow.
A state machine workflow consists of set of states with one state marked as 'start' state and one as 'final' state. Every state has an event associated with it and based on those events, workflow transitions from one state to another. It always starts from 'start' state and once it reaches the 'final' state, the workflow is assumed to be complete.
Few points about composition of a state machine workflow :
Following are the steps to create a state machine workflow using Visual Studio 2005 and WF extensions for Visual Studio.
private void codeActivity1_ExecuteCode(object sender, EventArgs e)
{
Console.WriteLine("In code activity of start state");
}
private void codeActivity2_ExecuteCode(object sender, EventArgs e)
{
Console.WriteLine("In code activity of middle state");
}
using System;
using System.Threading;
using System.Workflow.Runtime;
namespace SimpleStateMachine
{
static class MainProgram
{
static AutoResetEvent waitHandle = new AutoResetEvent(false);
static void Main()
{
using (WorkflowRuntime workflowRuntime = new WorkflowRuntime())
{
try
{
workflowRuntime.StartRuntime();
workflowRuntime.WorkflowCompleted += OnWorkflowCompleted;
workflowRuntime.WorkflowTerminated += OnWorkflowTerminated;
Type type = typeof(Workflow1);
workflowRuntime.CreateWorkflow(type).Start();
Console.WriteLine("Running the workflow. Waiting for the timer events...");
waitHandle.WaitOne();
}
catch (Exception e)
{
Console.WriteLine("Encountered an exception. Exception Source: {0}, Exception Message: {1} ", e.Source, e.Message);
}
finally
{
if (workflowRuntime != null)
workflowRuntime.StopRuntime();
Console.WriteLine("WorkFlow Completed");
}
}
}
static void OnWorkflowCompleted(object sender, WorkflowCompletedEventArgs instance)
{
waitHandle.Set();
}
static void OnWorkflowTerminated(object sender, WorkflowTerminatedEventArgs e)
{
Console.WriteLine(e.Exception.Message);
waitHandle.Set();
}
}
}
<StateMachineWorkflowDesigner xmlns:ns0="clr-namespace:System.Drawing;Assembly=System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" Name="Workflow1" Location="30, 30" Size="668, 554" AutoSize="False" AutoSizeMargin="16, 24" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/workflow">
<StateMachineWorkflowDesigner.DesignerConnectors>
<StateDesignerConnector TargetConnectionIndex="0" TargetStateName="middleState" SourceConnectionIndex="0" TargetConnectionEdge="Top" SetStateName="setStateActivity1" SourceStateName="Workflow1InitialState" SourceConnectionEdge="Right" TargetActivity="middleState" SourceActivity="Workflow1InitialState" EventHandlerName="eventDrivenActivity1">
<StateDesignerConnector.Segments>
<ns0:Point X="193" Y="110" />
<ns0:Point X="294" Y="110" />
<ns0:Point X="294" Y="341" />
</StateDesignerConnector.Segments>
</StateDesignerConnector>
<StateDesignerConnector TargetConnectionIndex="0" TargetStateName="finalState" SourceConnectionIndex="0" TargetConnectionEdge="Top" SetStateName="setStateActivity2" SourceStateName="middleState" SourceConnectionEdge="Right" TargetActivity="finalState" SourceActivity="middleState" EventHandlerName="eventDrivenActivity2">
<StateDesignerConnector.Segments>
<ns0:Point X="361" Y="382" />
<ns0:Point X="500" Y="382" />
<ns0:Point X="500" Y="190" />
<ns0:Point X="412" Y="190" />
<ns0:Point X="412" Y="198" />
</StateDesignerConnector.Segments>
</StateDesignerConnector>
</StateMachineWorkflowDesigner.DesignerConnectors>
<StateMachineWorkflowDesigner.Designers>
<StateDesigner Name="Workflow1InitialState" Location="46, 69" Size="160, 80" AutoSizeMargin="16, 24">
<StateDesigner.Designers>
<EventDrivenDesigner Size="110, 292" Name="eventDrivenActivity1" Location="54, 100">
<EventDrivenDesigner.Designers>
<DelayDesigner Size="90, 40" Name="delayActivity1" Location="64, 172" />
<CodeDesigner Size="90, 40" Name="codeActivity1" Location="64, 242" />
<SetStateDesigner Size="90, 50" Name="setStateActivity1" Location="64, 312" />
</EventDrivenDesigner.Designers>
</EventDrivenDesigner>
</StateDesigner.Designers>
</StateDesigner>
<StateDesigner Name="middleState" Location="214, 341" Size="160, 80" AutoSize="False" AutoSizeMargin="16, 24">
<StateDesigner.Designers>
<EventDrivenDesigner Size="110, 292" Name="eventDrivenActivity2" Location="309, 148">
<EventDrivenDesigner.Designers>
<DelayDesigner Size="90, 40" Name="delayActivity2" Location="319, 220" />
<CodeDesigner Size="90, 40" Name="codeActivity2" Location="319, 290" />
<SetStateDesigner Size="90, 50" Name="setStateActivity2" Location="319, 360" />
</EventDrivenDesigner.Designers>
</EventDrivenDesigner>
</StateDesigner.Designers>
</StateDesigner>
<StateDesigner Name="finalState" Location="332, 198" Size="160, 80" AutoSizeMargin="16, 24" />
</StateMachineWorkflowDesigner.Designers>
</StateMachineWorkflowDesigner>
Running the workflow. Waiting for the timer events...
In code activity of start state
In code activity of middle state
WorkFlow Completed
~tata & take care~
Other Posts
Windows Workflow foundation provides lot of services which can be plugged into workflow runtime based on the requirement. This reduces the overhead on runtime by having lot of services loaded without being used. These services come by default implementations but are fully extensible.
The main services which come with framework are :
Apart from extending above services, custom services can also be created and added to runtime.
Services are added to runtime using AddService method of the WorkflowRuntime class.
~bye & take care~
Other Posts
This tutorial covers following :
To start follow the first three steps as in following post.
private void codeCondition1(object sender, EventArgs e)
{
Console.WriteLine("i equals zero is true");
}
private void codeCondition2(object sender, EventArgs e)
{
Console.WriteLine("i equals one is true");
}
using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Collections;
using System.Drawing;
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 RuleCondition
{
public partial class Workflow1 : SequentialWorkflowActivity
{
int i=1;
private void codeCondition1(object sender, EventArgs e)
{
Console.WriteLine("i equals zero is true");
}
private void codeCondition2(object sender, EventArgs e)
{
Console.WriteLine("i equals one is true");
}
}
}
using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Workflow.Runtime;
using System.Workflow.Runtime.Hosting;
namespace RuleCondition
{
class Program
{
static AutoResetEvent waitHandle = new AutoResetEvent(false);
static void Main(string[] args)
{
using(WorkflowRuntime workflowRuntime = new WorkflowRuntime())
{
workflowRuntime.WorkflowCompleted += delegate(object sender, WorkflowCompletedEventArgs e) {OnCompleted();};
workflowRuntime.WorkflowTerminated += delegate(object sender, WorkflowTerminatedEventArgs e)
{
Console.WriteLine(e.Exception.Message);
waitHandle.Set();
};
WorkflowInstance instance = workflowRuntime.CreateWorkflow(typeof(RuleCondition.Workflow1));
instance.Start();
waitHandle.WaitOne();
}
}
static private void OnCompleted()
{
waitHandle.Set();
Console.WriteLine("wf completed");
Console.Read();
}
}
}
i equals one is true
wf completed
<RuleDefinitions xmlns="http://schemas.microsoft.com/winfx/2006/xaml/workflow">
<RuleDefinitions.Conditions>
<RuleExpressionCondition Name="iEqualsZero">
<RuleExpressionCondition.Expression>
<ns0:CodeBinaryOperatorExpression Operator="ValueEquality" xmlns:ns0="clr-namespace:System.CodeDom;Assembly=System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
<ns0:CodeBinaryOperatorExpression.Left>
<ns0:CodeFieldReferenceExpression FieldName="i">
<ns0:CodeFieldReferenceExpression.TargetObject>
<ns0:CodeThisReferenceExpression />
</ns0:CodeFieldReferenceExpression.TargetObject>
</ns0:CodeFieldReferenceExpression>
</ns0:CodeBinaryOperatorExpression.Left>
<ns0:CodeBinaryOperatorExpression.Right>
<ns0:CodePrimitiveExpression>
<ns0:CodePrimitiveExpression.Value>
<ns1:Int32 xmlns:ns1="clr-namespace:System;Assembly=mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">0</ns1:Int32>
</ns0:CodePrimitiveExpression.Value>
</ns0:CodePrimitiveExpression>
</ns0:CodeBinaryOperatorExpression.Right>
</ns0:CodeBinaryOperatorExpression>
</RuleExpressionCondition.Expression>
</RuleExpressionCondition>
<RuleExpressionCondition Name="iEqualsOne">
<RuleExpressionCondition.Expression>
<ns0:CodeBinaryOperatorExpression Operator="ValueEquality" xmlns:ns0="clr-namespace:System.CodeDom;Assembly=System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
<ns0:CodeBinaryOperatorExpression.Left>
<ns0:CodeFieldReferenceExpression FieldName="i">
<ns0:CodeFieldReferenceExpression.TargetObject>
<ns0:CodeThisReferenceExpression />
</ns0:CodeFieldReferenceExpression.TargetObject>
</ns0:CodeFieldReferenceExpression>
</ns0:CodeBinaryOperatorExpression.Left>
<ns0:CodeBinaryOperatorExpression.Right>
<ns0:CodePrimitiveExpression>
<ns0:CodePrimitiveExpression.Value>
<ns1:Int32 xmlns:ns1="clr-namespace:System;Assembly=mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">1</ns1:Int32>
</ns0:CodePrimitiveExpression.Value>
</ns0:CodePrimitiveExpression>
</ns0:CodeBinaryOperatorExpression.Right>
</ns0:CodeBinaryOperatorExpression>
</RuleExpressionCondition.Expression>
</RuleExpressionCondition>
</RuleDefinitions.Conditions>
</RuleDefinitions>
~bye & take care~
Other Posts
If you are new to WF pls read my previous posts on WF before proceeding with this.
In this post i will cover following :
To start follow the first three steps as in following post.
In the next step drag and drop the IfElse activity on to the empty workflow file. The ifElseActivity with two ifElseBranchActivity will be added to your workflow.
private void Condition1(object sender, ConditionalEventArgs e)
{
}
private void Condition2(object sender, ConditionalEventArgs e)
{
}
using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Collections;
using System.Drawing;
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 SequentialWF
{
public partial class Workflow1 : SequentialWorkflowActivity
{
private void Condition1(object sender, ConditionalEventArgs e)
{
Console.WriteLine("condition one evaluated");
e.Result=true;
}
private void Condition2(object sender, ConditionalEventArgs e)
{
Console.WriteLine("condition two evaluated");
e.Result=false;
}
private void conditionCode1(object sender, EventArgs e)
{
Console.WriteLine("condition one executed");
}
private void conditionCode2(object sender, EventArgs e)
{
Console.WriteLine("condition two executed");
}
}
}
condition one evaluated
condition one executed -
condition one evaluated
condition two evaluated
condition two executed
~bye & take care~
Other Posts
Most of the workflow we see in our daily lives are multi path which means based on different condition they take different path before getting completed.
Be it a financial workflow like Funds Transfer happening in Corporate environment which based on amount goes to different approvers or a non-financial workflow like leave approval in an enterprise which goes to different approver based on who initiates the leave request.
WF default activity library provides IfElseActivity + IfElseBranchActivity activity to simulate condition based workflow.
WF provides two methods of defining condition in workflow :
if (i == 0)
{
Result = true;
}
else
{
Result = false;
}
~bye & take care~
Other Posts
This post gives step by step details on how to build a simple sequential workflow using Code Activity.
It assumes that all the components required to develop workflow apps have been installed. List can be obtained here.
Step 1 : Create an empty workflow project in VS 2005. Empty project helps in understanding the architecture of app better as we build from scratch.
Step 2 : As we will be building a console application, change the output type of the project to 'Console Application' using project properties.
Step 3 : Add a new item to the project- 'Sequential Workflow (with code separation)' where we will specify the workflow implementation. This will add two files to your project Workflow1.xoml and Workflow1.xoml.cs.
Step 4 : Double clicking Workflow1.xoml will open the empty workflow diagram. Drag and drop code activity from workflow toolbox on the workflow.In the property window of the code activity enter the value for ExecuteCode parameter which will generate the method by that name. e.g. Code1.
Step 5 : Add code to the Code1 method. Workflow1.xoml.cs will look like this :
namespace HelloWorld
{
public partial class Workflow1 : SequentialWorkflowActivity
{
private void Code1(object sender, EventArgs e)
{
Console.WriteLine("Hello workflow enabled world !");
}
}
}
Step 6 : Add a new code file to your project with Main method. This file will be used to host the workflow and execute it.
The code in the file should be :
namespace HelloWorld
{
class Program
{
static void Main(string[] args)
{
using(WorkflowRuntime workflowRuntime = new WorkflowRuntime())
{
AutoResetEvent waitHandle = new AutoResetEvent(false);
workflowRuntime.WorkflowCompleted += delegate(object sender, WorkflowCompletedEventArgs e) {waitHandle.Set();};
workflowRuntime.WorkflowTerminated += delegate(object sender, WorkflowTerminatedEventArgs e)
{
Console.WriteLine(e.Exception.Message);
waitHandle.Set();
};
WorkflowInstance instance = workflowRuntime.CreateWorkflow(typeof(HelloWorld.Workflow1));
instance.Start();
waitHandle.WaitOne();
Console.ReadLine();
}
}
}
}
Step 7 : Build the solution, the output should like like this :
Hello workflow enabled world !
The code in the markup file will be like this :
<SequentialWorkflowActivity x:Class="HelloWorld.Workflow1" x:Name="Workflow1" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/workflow">
<CodeActivity x:Name="codeActivity1" ExecuteCode="Code1" />
</SequentialWorkflowActivity>
Let me just explain some code now :
Class WorkFlow1 is quite simple and as we developed Sequential Workflow we used SequentialWorkFlowActivity. In main program we created an instance of WorkflowRuntime and using that instance we created the instance of our workflow by passing our workflow type to it. Use start() method to execute the workflow. Workflow runtime by default starts all the workflows async. in a separate thread and thats why we used the AutoResetEvent so that main program doesn't exit before our workflow gets completed.
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Here is a list/link to components which are required to develop/run windows workflow enabled applications :
Other Posts
The .NET 3.0 composition can be expressed as below :
.NET 3.0 = .NET 2.0 + WCF + WPF + WF + CardSpace
WCF is Windows Communication Foundation for distributed computing, WPF is Windows Presentation Foundation for building interactive UI, WF is Windows Workflow Foundation and CardSpace is an identity management framework.
WF can be defined as a composition of the programming model, engine and tools for building workflow enabled applications for Windows platform. This is the single workflow technology which will be used by all Windows products and also custom applications build for windows platform.
As in real world, workflow in WF is also a set of activities where the control can go from one activity to another based on decisions or rules.
WF supports three kinds of workflow authoring styles :
WF architecture mainly consists of following components :
In programming terms a workflow can be defined as a class in code file or defined in markup file.
using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Collections;
using System.Drawing;
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 HelloWorldWF
{
public partial class Workflow1 : SequentialWorkflowActivity
{
private void codeActivity1_code(object sender, EventArgs e)
{
Console.WriteLine("Hi Vikas");
}
}
}
OR
<SequentialWorkflowActivity x:Class="HelloWorldWF.Workflow1" x:Name="Workflow1" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/workflow">
<CodeActivity x:Name="codeActivity1" ExecuteCode="codeActivity1_code" />
</SequentialWorkflowActivity>
The above workflow Workflow1 is a sequential type of workflow with only one activity called codeActivity1 which executes the method codeActivity1_code.
WF supports three kinds of authoring modes :
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