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  • Microsoft Windows Workflow Foundation 4.0 Cookbook
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Microsoft Windows Workflow Foundation 4.0 Cookbook

Microsoft Windows Workflow Foundation 4.0 Cookbook

By : Andrew Zhu
4 (7)
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Microsoft Windows Workflow Foundation 4.0 Cookbook

Microsoft Windows Workflow Foundation 4.0 Cookbook

4 (7)
By: Andrew Zhu

Overview of this book

Windows Workflow Foundation 4.0 (WF) is a significant part of .NET Framework 4.0. WF makes workflow technology available to every single programmer that uses the .NET Framework 4.0. It is easy to create long running and distributed programs using WF with the right knowledge. With this book, you will discover that working with workflows is easy. This book provides both step-by-step recipes and relevant background information. It covers all the important aspects of Windows Workflow Foundation 4.0. The best thing about this book is that all recipes are based on real-world experiences of Andrew Zhu. Andrew is a global WF and BizTalk technology support engineer for Microsoft. This book covers everything you need to know, when working with workflows. Get to grips with flow control activities, messaging, and transaction processes with easy to understand steps followed by explanations. You will quickly learn to use collection and custom WF activities and WF services.You will see recipes that illustrate integration of Windows Workflow with other applications such as WPF, ASP.NET, WCF service.Lastly, you will discover how easily you can customize W4 Designer with WF rule engine and others.
Table of Contents (15 chapters)
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Microsoft Windows Workflow Foundation 4.0 Cookbook
Microsoft Windows Workflow Foundation 4.0 Cookbook
Credits
Credits
About the Author
About the Author
About the Reviewers
About the Reviewers
Foreword
Foreword
Preface
Preface
Free Chapter
1
Workflow Program
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Workflow Program
Introduction
Creating the first WF program: HelloWorkflow
Creating a WF program using C# Code
Initializing a WF program using InArguments
Creating a WF program using OutArgument
Creating a WF program using InOutArgument
Using Variable in a WF program
Running a WF program asynchronously
Customizing a MyReadLine activity with Bookmark
Converting a WF program instance to XAML
Loading up a WF program from an XAML file
Testing a WF program with a unit test framework
Debugging a WF program
2
Built-in Flow Control Activities
Built-in Flow Control Activities
Introduction
Using the Foreach activity
A number guessing game in Sequence
A number guessing game using a flowchart
Using the InvokeMethod activity
Using the Switch<T> activity in Sequence workflow
Using the FlowSwitch<T> activity
Using the Parallel activity
Using the ParallelForEach<T> activity
Using the Pick activity
Handling errors
3
Messaging and Transaction
Messaging and Transaction
Introduction
Creating a pure WCF service
Receiving and replying to a WCF message
Receiving and replying to a WCF message in code workflow
Sending and receiving a reply to a WCF message
Sending and receiving a reply to a WCF message in code workflow
Using CancellationScope activity
Performing a transaction by using TransactionScope activity
Performing compensation by using Compensable activity
Performing manual compensation by using Compensate activity
Performing confirmation by using Confirm activity
4
Manipulating Collections
Manipulating Collections
Introduction
Printing collection items
Using AddToCollection<T> activity
Using ClearCollection<T> activity
Using RemoveFromCollection<T> activity
Using ExistsInCollection<T> activity
5
Custom Activities
Custom Activities
Introduction
Creating an activity by inheriting the root activity
Creating a FileWriter activity
Creating a SendEmail activity
Creating an Input Message activity using Bookmark
Creating an Asynchronous HTTP Get activity
Creating a Composite activity
Creating an Activity Designer for the SendEmail activity
Creating an Activity Designer for theMySquence activity
6
WF4 Extensions
WF4 Extensions
Introduction
Configuring ETW tracking
Creating FileTrackingParticipant
Configuring the SQL persistence store
Loading a persisted workflow from the database
Using a persistence participant to persist additional data
Using a customized extension
7
Hosting Workflow Applications
Hosting Workflow Applications
Introduction
Hosting a workflow service in IIS7
Hosting workflow in ASP.NET
Hosting workflow in WPF
Hosting workflow in a Windows Form
8
Custom Workflow Designer
Custom Workflow Designer
Introduction
Implementing designer layout
Implementing Toolbox, Workflow Designer, and Property Inspector views
Implementing New Workflow and Load Workflow events
Implementing Save and Save As events
Implementing XAML Workflow Tab and Run events
Implementing visual tracking
Index
Index

Loading up a WF program from an XAML file

In this task, we will run a WF program by loading it from an XAML file.

How to do it...

  1. Create a workflow project:

    Create a new Workflow Console Application under the Chapter01 solution and name the project as LoadUpWorkflowFromXML.

  2. Author a workflow:

    Author the Workflow1.xaml file; this workflow will print a string to console as shown in the following screenshot:

  3. Create code to load up the workflow instance from an XAML string:

    Open Program.cs file and change code as follow:

    using System;
using System.Activities;
using System.Activities.Statements;
using System.IO;
using System.Collections;
using System.Text;
using System.Activities.XamlIntegration;

namespace LoadUpWorkflowFromXML {
    class Program {
        static void Main(string[] args) {
            string filePath=           @"C:\WF4Cookbook\Chapter01\LoadUpWFFromXML\Workflow1.xaml";
            string tempString="";
            StringBuilder xamlWFString = new StringBuilder();
            StreamReader xamlStreamReader = 
                new StreamReader(filePath);
            while (tempString != null){
                tempString = xamlStreamReader.ReadLine();
                if (tempString != null) {
                    xamlWFString.Append(tempString);
                }
            }
            Activity wfInstance = ActivityXamlServices.Load(
                new StringReader(xamlWFString.ToString()));
            WorkflowInvoker.Invoke(wfInstance);
        }
    }
}

    Tip

    We may need to change the file path according to our real environment.

  4. Run it:

    Set LoadUpWorkflowFromXML as Startup project. Press Ctrl+F5 to build and run the workflow without debugging. The application should run in a console window and print the message as shown in the following screenshot:

How it works...

We use the following code block to read a workflow XML string from file and store the string in xamlWFString: 

string filePath=           @"C:\WF4Cookbook\Chapter01\LoadUpWFFromXML\Workflow1.xaml";
string tempString="";
StringBuilder xamlWFString = new StringBuilder();
StreamReader xamlStreamReader = 
new StreamReader(filePath);
while (tempString != null)
{
    tempString = xamlStreamReader.ReadLine();
    if (tempString != null) 
    {
        xamlWFString.Append(tempString);
    }
}

Then, using the following statement, ActivityXamlServices reads the XML workflow and builds up a workflow object graph:

Activity wfInstance = ActivityXamlServices.Load(
                new StringReader(xamlWFString.ToString()));
End of Section 12
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