1. Introduction to Windows Workflow Foundation
Silvano Coriani
Developer Evangelist Microsoft

2. Agenda What is Windows Workflow Foundation?
Architecture & Core concepts
Building Workflows
Introduction to Activities
Workflow Styles
Workflow Authoring Tools
Runtime services
Workflow communications

3. Workflow Software Challenges
Real World Behavior
Software Challenges
Long Running and Stateful
Workflows run for up to 30 days and must maintain state throughout
“Orders are confirmed in
48 hours and shipped within 30 days”
“Most suppliers
confirm our orders but some forget and we need to followup”
Flexible Control Flow
Flexibility for people to override or skip steps in the workflow
Transparency
Rendering runtime state within a visualization of the workflow control flow
“What is the status of this order and what is the next step?”

4. Why Workflow Technology?
Developer Productivity
Workflows technology provides abstractions
convenient to describe real world scenarios
Workflow software challenges
Workflows are long running and stateful
Workflows require flexible control flow
Workflows must provide transparency

5. Microsoft’s Workflow Strategy is …
to provide Windows Workflow Foundation as a part of the developer framework for Windows
and enterprise applications that build on top of Windows Workflow Foundation for specific scenarios.
A ISV developer building a line of business application chooses to use Windows Workflow Foundation within the business logic of their application.
An enterprise customer uses BizTalk Server to provide system workflow across their existing line of business applications and trading partners to reduce their cycle-times and increase business visibility in a high-volume environment.
For Example
For Example

6. Windows Workflow Foundation
Deliver best-in-class workflow platform & tools for Microsoft products and partner/customer ecosystem
Single workflow technology for Windows
Available to all customers of Windows
Available for use across a broad range of scenarios
Redefining workflow
Extensible framework & API to build workflow centric products
One technology for human and system workflow
Take workflow mainstream
Incremental learning for mainstream .NET developer
Fundamental part of the Office “12” value proposition
Strong workflow partner & solution ecosystem

7. What is a workflow? A set of activities that coordinate people
and / or software...
Example activities….
EscalateToManager
CheckInventory
…organized into some form of workflow.
Like a flowchart….
Or a state diagram….

8. Workflow Scenario Spectrum
System Workflow
Human Workflow
Participants: people, roles
Flow style: flexible, dynamic
Data: unstructured, documents
Participants: apps, services
Flow style: prescriptive, protocols
Data: structured, transactional
Business to Business
Supply Chain Mgmt…
Information Worker
Document Review…
Line of Business Apps
Quote to Cash, Sales Automation…
CRM
ERP
IT Management
New Hire Provisioning, Trouble Ticket,…
.NET Developer
Pageflow, Service Coordination…
Windows Workflow Foundation

9. Windows Workflow Foundation
Visual Designer
Key Concepts
Workflows are a set of Activities
A Workflow
Workflows run within a Host Process: any application or server
Developers can build their own Custom Activity Libraries
An Activity
Custom Activity Library
Components
Windows
Workflow Foundation
Base Activity Library: Out-of-box activities and base for custom activities
Base Activity Library
Runtime Engine: Workflow execution and state management
Runtime Engine
Runtime Services: Hosting flexibility and communication
Runtime Services
Visual Designer: Graphical and code-based construction
Host Process

10. Workflow Basics A workflow is a class
Imports System.Workflow.Activities
Public Class MyWorkflow
Inherits SequentialWorkflow …
End Class
A workflow class may be defined in markup
<?Mapping XmlNamespace="Activities" ClrNamespace="System.Workflow.Activities" Assembly="System.Workflow.Activities" ?>
<SequentialWorkflow x:Class="MyWorkflow" xmlns="Activities" xmlns:x="Definition"> …
</SequentialWorkflow>

11. Workflow Execution My Application Create instance Execute until idle
rt.StartWorkflow(typeof(WF1));
Invoke1
WF1 Instance 1
App calls StartWorkflow(…)
Sequence 2
Instance Manager:
Loads workflow type
Creates instance
Enqueues WF1 with Scheduler
WF1
OnEvent1
Execute
MyWF.dll
Execute until idle 3
Scheduler dequeues WF1 and calls Executor (SequentialWorkflow base)
which enqueues Sequence
SequentialWorkflow
Execute
Base
Activity
Library
Sequence
Execute 4
Dequeue Sequence and call Executor
which enqueues OnEvent1
Activity
Save
Dequeue OnEvent1 and call Executor
which subscribes to event 5
Instance Manager
Persist to disk
Runtime
Engine
InstanceMgr calls Save() on WF1 (Activity base class) to serialize instance and gets back stream 6
Scheduler
WF1
Sequence
OnEvent1
Instance Mgr call Persistence service passing serialized stream - Persistence service saves to disk 7
Runtime
Services
WF1
Persistence

12. Activity Basics Activities are the building blocks of workflows
The unit of execution, re-use and composition
Basic activities are steps within a workflow
Composite activities contains other activities EG: Sequence
Base Activity Library provides out-of-the-box activity set
Partners and customers author custom activities EG: “ApproveOrder”
Activities are classes:
Properties and events are defined by the activity author and programmable from workflows
Has methods that are coded by the activity author but invoked by the workflow runtime (EG: Execute) or designer
Can be built into workflow assemblies or deployed as re-usable libraries

13. Activities: Optional Features
Companion Classes
[Designer(typeof(MyDesigner))]
[Validator(typeof(MyValidator))]
[CodeGenerator(typeof(MyCodeGen))]
[Serializer(typeof(MySerializer))]
[ToolboxItem(typeof(MyToolboxItem))]
Designer
Validator
Serializer
Code Generator
ToolboxItem
Behaviors
[SupportsTransaction]
[SupportsExceptionHandlers]
Transactions
public class MyActivity: Activity
{ ... }

14. Activities: An Extensible Approach
Vertical-specific activities & workflows
Best-practice IP & Knowledge
Domain-Specific Workflow Packages
Compliance
RosettaNet
CRM
IT Mgmt
Base Activity
Library
Custom Activity Libraries
Compose
activities
Extend
activity
Author new
activity
Out-of-Box
Activities
OOB activities, workflow types, base types
General-purpose
Activity libraries define workflow constructs
Create/Extend/ Compose activities
App-specific building blocks
First-class citizens
Sequencing engine driven by activities (no fixed language)

15. Flexible Control Flow Sequential Workflow State Machine Workflow
structure
prescribes
processing order
External
events drive
processing
order
Step1
State1
Event
State2
Step2
Event
Prescriptive, formal
Automation scenarios
Flowchart metaphor
Reactive, event-driven
Skip/re-work, exception handling
Graph metaphor
Rules-driven Activities
Rule1
Step1
Rules + data state
drive processing
order
Data
Rule2
Step2
Data-driven
Simple Conditions, complex Policies
Constrained Activity Group

16. Spectrum of Workflow Authoring Tools
Line of Business Manager / End users
Wizards
Business Analyst
Visio Like
Script Developers or VARs
Script Like
Code Developers or ISVs
Windows Workflow Foundation Designer
Commonality between Tools:
Support a common object model for describing Workflow information
The object model needs to be exchangeable between tools

17. Take Workflow Mainstream: Design
Activity Designer
Sequential Designer
State Machine Designer
Workflow Designers
(À la ‘ASP.NET’ Designer)
Create new workflows
Visual (/code) authoring
Seamlessly integrate .NET code with round-tripping
Visual debugging
Themes support
Designer re-hosting
Activity Designer
(À la ‘UserControl’ Designer)
Create new activities
Visual (/code) authoring
Inherit from base activities or start from scratch
Black-box/Gray-box composition support
Consistent and Familiar Experience for Workflow Development

18. Workflow Authoring Modes
Markup Only
“Declarative”
Markup and
Code
Code Only
Application
Generated
C#/VB
C#/VB
App creates activity
tree and serializes
XAML
XAML
XML defines
workflow structure
logic and data flow
XML defines
workflow
Code-beside
defines extra logic
Code creates
workflow
in constructor
C#/VB
XAML
Workflow Compiler
wfc.exe
.NET assembly
ctor defines
workflow
C#/VB Compiler

19. Workflow Enabled Office Take Workflow Mainstream: Office “12”
SharePoint: Start/participate, customize, and track workflows
Workflows run inside SharePoint and are accessible across the Office System
OutLook: Receive notifications and track tasks
FrontPage:
Create and
customize workflows
Workflow Enabled Office
Word, PowerPoint,
Excel, InfoPath: Start/participate in SharePoint workflow
Take Workflow Mainstream: Office “12”
Office “12” Workflow Vision
Provide document centric workflow as an integrated part of the Office experience
Empower information workers with common workflow solutions and activities out of the box
Empower organizations to build sophisticated workflow using the full functionality of the broader platform

20. Runtime Engine And Services
My workflow
Windows Workflow Foundation
Base Activity Library
Runtime Engine
Provides intrinsic behaviors to activities
Tracking Infrastructure
State
Management
Workflow Execution
Dynamic
Update
Should mention that there are a total of 5 services we provide. We may want to enumerate them all here.
Need to mention some host samples. SharePoint would be a host for our technology. Biztalk in the future would be a host for our technology. A WinForm application and a Windows Service could be also considered a host.
Runtime Services
Hosting flexibility - pluggable implementations (with defaults)
Persistence
Communication
Tracking …
Host Process

21. Runtime Services The workflow runtime is lightweight
Depends on a set of services
Only Threading is required
Often you also want Transactions and Persistence
Add services programmatically or using a config file
What ships in System.Workflow.Runtime.Hosting?
Abstract service definitions
Concrete service implementations
DefaultThreadingService (asynchronous)
ManualThreadingService (synchronous; for ASP.NET scenarios)
DefaultTransactionService
SqlPersistenceService

22. Runtime Services Host Application App Domain Runtime Services SQL
TimerService manages timers – e.g. Delay activity.
Services
Out of Box Services are provided that support SQL Server 2000 & 2005
TimerService
PersistenceService stores and retrieves instance state.
SQL
PersistenceService
TrackingService
TrackingService manages profiles and stores tracked information.
The runtime uses default implementation of these services. But they can be replaced by your own implementations. Out-of-the-box we offer SQL as persistence store for Tracking, State Persistence, and Timer persistence.
ThreadingService
TransactionService
Common resource services for managing threading and creating transactions

23. Out-of-Box Services ASPNetThreadingService
Synchronous threading service used for in-line execution; used by ASP module for web services
DefaultThreadingService
Used for asynchronous execution of workflows; uses default .Net thread pool
DefaultWorkflowTransactionService
Creates .NET transactions
SharedConnectionWorkflowTrans-actionService
Sql* services share connection to SqlServer
InMemoryTimerService
Stores timer information in-memory, i.e. for Delay activity
SqlTimerService
Stores timer information in SqlServer/MSDE; i.e. for Delay activity
SqlStatePersistenceService
Stores workflow instance state information in SqlServer/MSDE
SqlTrackingService
Stores tracking information in SqlServer/MSDE

24. Workflow State Management
Many workflows are long running
A workflow instance is idle when it has no runnable work
WF unloads-on-idle by default, but the host can take full control
Loading/unloading is not a concern of the workflow developer or the application developer
Persistence points are checkpoints
Transactions
Enable crash recovery
Persistence occurs at:
Closure of a transaction
Closure of any activity marked [PersistOnClose]
Closure of the workflow
Custom services can participate in the transaction
Even if there is no transaction modeled in the workflow
The transaction is committed when a workflow persistence point is reached

25. Enabling Workflow Persistence
Persistence Support for Workflow Instances
Create the SQL database with the SqlStatePersistence schema
Create a Workflow Runtime
Define Connection String
Register StatePersistenceService with Runtime
Register TimerService with Runtime
Start the Workflow
Loading and Unloading uses StatePersistenceService
private void RunWorkflow() {
WorkflowRuntime wr = new WorkflowRuntime();
string connectionstring = "Initial Catalog=Persistence;Data
Source=localhost;Integrated Security=SSPI;";
wr.AddService(new SqlStatePersistenceService(connectionstring));
wr.AddService(new SqlTimerService(connectionstring));
wr.StartWorkflow(typeof(SimpleWorkflow)); }
We need to mention that I’m using our OOB services. They could build their own. Make sure I mention it doesn’t have to be SQL DB.

26. Tracking Tracking Activities Service Workflow Instance
Track all state changes and data within the workflow
Emit tracking info from code
Dynamic changes
Profile
XML file that specifies what to track
Includes and excludes, state changes, data context, types
Object model to create
Tracking
Information
Tracking
Service
Need to mention that tracking services can go against any back end system not only RDBMS. Imagine a tracking service that goes against the Event Log, Files, or Raise Events. Need to verify when Tracking actually happens, how synchronous is it?
Write
Store
Activities
Profile
Workflow
Instance
Host Application
Query

27. Tracking Architecture
Workflow Runtime
Listener asks each services for their profile(s)
Service only gets called based on what is specified in the profile(s)
Multiple tracking services can be loaded per the application’s requirements
Workflow Instance
Profile
SqlTrackingService
Execution
Listener
FileTrackingService
Profile
SqlTrackingService Channel
FileTrackingService Channel

28. Enabling Workflow Tracking
Tracking Support for Workflow Instances
Define tracking profiles
Create workflow runtime
Define connection string
Register one or more TrackingService’s with the WorkflowRuntime
Start the workflow
Query tracking database – instance and activity information
private void RunWorkflow() {
WorkflowRuntime wr = new WorkflowRuntime();
string connectionstring = "Initial Catalog=Tracking;Data
Source=localhost;Integrated Security=SSPI;";
//Out of the Box Tracking Service
wr.AddService(new SqlTrackingService(connectionstring));
wr.StartWorkflow(typeof(SimpleWorkflow)); }
Need to mention that tracking services go beyond DB. They could be defined against the event logs, files, etc.

29. Workflow & Communications
The purpose of a workflow is often to coordinate work performed outside of its boundaries
Many workflows are long-running programs
Communication is an inherent need
The communication may be local (intra-process)
To and from your hosting application code
The communication may be remote
Web services
Windows Communication Foundation (Indigo)

30. Communication Architecture
Local Application
Remote Application
Communication Services
Proxy management
Correlation
Custom Host
ASP.NET
Local App Object
Local App Object
Web Service
Local App Object
Local App Object
Local App Object
Runtime
Scheduling
Workflow Runtime
Workflow Instances
WebServiceReceive
WebServiceResponse
InvokeWebService
InvokeMethod
EventSink
Activities
Model sending and receiving of data

31. Local Communication Architecture
.NET object managed by the runtime acts as a communication intermediary between the host and the workflow instances
Raises events into the workflow
Proxy for outbound method calls
Four components:
Local Communication Activities
Contract
Local Service
EventArgs
Application
Workflow
Method
Event
Workflow Runtime
Output
DataExchangeService
Input

32. Local Communication Activities Model sending and receiving data
EventSink activity
Model an event raised by a local object (Application  Workflow)
InvokeMethod activity
Model the invocation of a method on a local object (Workflow  Application)
OrderManager
WorkflowRuntime

33. Local Communication Contract Define pattern of communication
Write an interface that defines the contract for communication with the workflow
Events for inbound data (to workflow)
Methods for outbound data (from workflow)
Mark as [DataExchangeService]
[DataExchangeService]
public interface IOrderManager {
// Create a workflow instance to process the order
event EventHandler<OrderEventArgs> OrderSubmitted;
// The workflow instance will later call one of these methods
void Approve(string orderId);
void Reject(string orderId); }

34. Local Communication Service Implement class
Implement the interface you’ve defined
Singleton (will be shared by all workflow instances)
Register with the runtime
public class OrderManager : IOrderManager {
// Create a workflow instance to process the order
public event EventHandler<OrderEventArgs> OrderSubmitted;
// The workflow instance will later call one of these methods
public void Approve(string orderId) { … }
public void Reject(string orderId) { … } }
WorkflowRuntime runtime = new WorkflowRuntime();
OrderManager orderManager = new OrderManager();
runtime.AddService(orderManager);

35. Local Communication Event Args Define event data
The runtime intercepts events raised by the registered local object, and delivers them to the right workflow instances
Must derive from WorkflowMessageEventArgs and include the workflow instanceId
Conceptually, the registered local object is addressing a workflow instance when it raises an event
public class OrderEventArgs : WorkflowMessageEventArgs {
public OrderEventArgs(Guid instanceId, string orderId)
: base(instanceId) … }

36. Coordinating Services
Workflows are an excellent way to coordinate services
Service interaction becomes:
Declarative – modeled using activities in a workflow
Transparent - to the outside world
Visual – for designing, debugging, and monitoring
Composable - Data can be flowed from activities/services
Simplified - Workflows simplify message exchange patterns
Flexible - Easily be modified and dynamically changed
Services
Workflow

37. Implementing Services using Workflow
Challenges developing services today
Services are often used together as part of a business process, but are not explicitly associated
Services often front-end, long-running business processes
Workflows are an excellent way to implement service logic
State management across multiple service interactions
Services are explicitly associated in a workflow model
Implementation can be transparent
Enables runtime visibility into the state of the service
Runtime behavior is configurable
Tracking, persistence, etc.
Services
Workflow

38. Web Services Activities
InvokeWebService
Like Visual Studio Add Web Reference
Session-aware
Can manipulate the proxy before the call
For example, to set credentials
Parameter binding
WebServiceReceive, WebServiceResponse
Model 1-way and 2-way requests to the workflow
Define web service contract as an interface
Generate default web service project plus artifacts with a single click in Visual Studio

39. Web Services Hosting WorkflowWebHostingModule WorkflowWebService
ASP.Net 2.0 IHttpModule
Session-based request routing
Not required to use this (replaceable)
WorkflowWebService
Default base class for published workflows
Not a required base class for your web services
Workflow Runtime Services
ASPNetThreadingService
Uses request thread to process workflow
WebTimerService
Persistent timer service

40. Web Services Build transparent, flexible, long-running web services
ASP.NET
Build transparent, flexible, long-running web services
Model all data entry and exit points
Host the workflow runtime in ASP.NET
WorkflowWebService
WorkflowWebHostingModule
Workflow Runtime
Workflow
Receive
Response
Invoke
Runtime Services
Session
Threading Service
Timers
Timer Service
Workflow State
Persistence Service

41. Why Workflow & Services?
Services make workflow more accessible
Workflows make services more composable
Services
Services
Workflow
While these two usage scenarios could absolutely be independent, they can also be used together. Imagine building a workflow that consumes several services, but it is actually exposed as a service itself so it can easily be accessed from another application – such as the User Interface.
We integrate software by exchanging messages with services
Two general usage scenarios:
Consuming services within a workflow
Accessing workflows as services
Services make workflow more accessible
Workflows make services more composable
Secure, reliable, transactional services
Unified API for communications
Support for key WS-* protocols
Transport selection
TCP, HTTP, Named Pipes, P2P, MSMQ, Custom
Multiple Message Exchange Patterns
Request-Response, Duplex, One-Way
Analogy – object-driven development vs. data-driven development
UML – state machines
Service implementation is opaque to client
Service implementation is also opaque to implementer, runtime, IT pro, knowledge worker and my mom – Enter Workflow

42. Workflow & Communications Foundation
Declarative control flow
Simplified programming model
Process visualization
Dynamic execution
Configurable runtime behavior
Secure, reliable, transactional services
Unified API for communications
Transport selection
Multiple Message Exchange Patterns
We integrate software by exchanging messages with services
Two general usage scenarios:
Consuming services within a workflow
Accessing workflows as services
Services make workflow more accessible
Workflows make services more composable
Secure, reliable, transactional services
Unified API for communications
Support for key WS-* protocols
Transport selection
TCP, HTTP, Named Pipes, P2P, MSMQ, Custom
Multiple Message Exchange Patterns
Request-Response, Duplex, One-Way
Analogy – object-driven development vs. data-driven development
UML – state machines
Service implementation is opaque to client
Service implementation is also opaque to implementer, runtime, IT pro, knowledge worker and my mom – Enter Workflow

43. WCF Activities
Prototype activities designed for direct communications using WCF
SendMessage
ReceiveMessage
SendReceive
ReceiveSend
Enables explicit asynchronous and sophisticated message exchange patterns
Workflows wire up communications to services by configuring these activities
Not provided with Windows Workflow Foundation

44. WCF with Local Services
Service Request
WCF Service
OrderManager
Local Service
Service Request
WCF Service

45. Workflow and BizTalk Server
Premium BPM server
Distinct server product
Use in B2B, EAI, BPM scenarios
Deployable solutions
Manageability, Scale-out
Design
Tools
Accelerators
Business
Activity
Monitor
And
Admin
Tools
Workflow
Orchestration
Messaging
Transformation
Future version will migrate to Windows Workflow Foundation for orchestration
Adapters
Workflow framework
Exposed via WinFX
Broad set of scenarios
Used to build solutions
Enables manageability
and scale-out in solutions
Use for building workflow into apps or workflow-enabled servers
Visual Studio Designer
WinFX
Windows Workflow
Foundation

46. Summary A single workflow technology for Windows
Platform level workflow framework for use within Microsoft products & ISV applications
Will be used by BizTalk Server, Office12, and Dynamics
Available to all Windows customers
Microsoft is redefining workflow
Unified technology for System & Human workflow
Multiple styles: sequential, rules-based, state machine
Supports dynamic interaction
Microsoft is taking workflow mainstream
Consistent and familiar programming model for reaching mainstream application developer
Available to millions of end-users through Office “12”
Extensible platform for ISVs

47. © 2006 Microsoft Corporation. All rights reserved.
This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.