Quick overview of WF

Quick overview of WF

WF 4.0 new features (PDC08)

MSDN Channel 9 link

- Activities have in/out Arguments that can be bound to scoped Variables

- persistence points, no-persist zones

- adapting to mid-stream process changes. activities can be updated midstream

- tracking service - 28'

- WF4 vs WF3 - 33'

- Support for Partial Trust Env

- Rehosting improvements (nothing in particular demo'd)

WF 4 custom activities

PDC 2008 cast on custom activities in WF 4

- Base Activity Library supports Interop, Error handling, etc

- Instead of binding properties across activities, Variables are now introduced to box the scope of the outgoing args of an activity.

- No real talk about passivation (Kenny Wolf's talk handles that)

- "custom execution patterns" -- 35'

- WorkflowInvoker class is new - can be used for firing up individual activities for debugging/unit testing

- Scheduling activities explicitly: AEC.ScheduleActivity()

- handling faults - 45.5'

- WorkflowElement class

- AEC.CreateNamedBookmark

- AEC.SetupAsyncOperationBlock - 53'

- Activity designers - 56.5'

- Rehosting designers - 63'

Usage of C# 3.0 features distracts the viewer of this demo a bit

Dish #2: A generic AbstractFactory class

#region Copyright
///Copyright 2008 Codesagar.
///DISCLAIMER: Author claims no responsibility for any damages whatsoever
///stemming out either directly or indirectly from the usage of any of the
///source code made available through Codesagar.
#endregion

using System;

namespace Factories
{
   /// <summary>
   /// Usage: TConcreteFactory is the concrete factory that implements this base
    /// class and creates instances of type TCreatedType (and its derived classes)
   /// </summary>
   /// <typeparam name="TConcreteFactory">Concrete factory type</typeparam>
   /// <typeparam name="TProduct">Product type to be created by the
    /// concrete factory
   /// </typeparam>
   public class AbstractFactory<TConcreteFactory, TProduct> :
       SingletonBase<TConcreteFactory>
        where TConcreteFactory : class, new()
       where TProduct : class
   {
       /// <summary>
       /// This is the factory class that must be implemented by your concrete
        /// factory instance.
       /// </summary>
       /// <param name="args">Arguments that your implementation of Create
        /// can accept.
       /// </param>
       /// <returns>Return the instance of your desired type TProduct or its
        /// subtype
       /// </returns>
       public virtual TProduct Create(params object[] args)
       {
           throw new NotImplementedException();
       }
   }

    class ExampleProduct { }
   class ExampleFactory : AbstractFactory<ExampleFactory, ExampleFactory>
   {
       public override ExampleFactory Create(params object[] args)
       {
           return new ExampleFactory();
       }
   }

    class ExampleClient
   {
       public void Demonstrate()
       {
           ExampleFactory.Instance.Create();
       }
   }

}

Dish #1: Generic Singleton base class

#region Copyright

///Copyright 2008 Codesagar.

///DISCLAIMER: Author claims no responsibility for any damages whatsoever

///stemming out either directly or indirectly from the usage of any of the

///source code made available through Codesagar.

#endregion

using System;

///Codesagar factory dishes

namespace Factories

{

    ///

    /// This class provides a generic singleton base class that provides a static member

    /// of the derived type tha points to the singleton instance. Ths class also provides

    /// the public singleton getter Instance to access the public interface of the derived 

    /// class.

    ///

    /// The derived class that should be used as a singleton

    public class SingletonBase where T : class, new()

    {

        #region protected static instance

        protected static T s_instance;

        #endregion

        #region protected constructor

        protected SingletonBase()

        {

        }

        #endregion

        #region Singleton interface

        public static T Instance

        {

            get

            {

                if (s_instance == null)

                {

                    T instance = new T();

                    // Insure all writes used to construct new value have been flushed.

                    // For more, see 

                    // http://blogs.msdn.com/brada/archive/2004/05/12/volatile-and-memorybarrier.aspx

                    System.Threading.Thread.MemoryBarrier();

                    s_instance = instance;

                }

                return s_instance;

            }

        }

        #endregion

    }

    ///

    /// A sample singleton class that derives its singleton properties

    /// from the Singleton

    ///

    class MySingleton : SingletonBase

    {

        public void Test()

        {

            Console.WriteLine("MySingleton::Test called!");

        }

    }

    public class Client

    {

        public void TestMySingleton()

        {

            MySingleton.Instance.Test();

        }

    }

}

Codesagar - Inauguration

Codesagar - thats what i could think of naming this blog dedicated to giving quick programming tips to achieve something worthwhile. A dedication to the gazzillion Bangalore fast food joints around every nook and corner that go by all sortsa names ending with "Sagar" :P 

Some quick reading tips for dish names (every code post is called a dish).

• # preceding a number means that the dish is in C# . Example: Dish#1 is in C#.
  
• ++ preceding a number means that the dish is in C++