An introduction to Workflow 4, the differences with earlier versions and examples

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27 August, 2010 WorkFlow 4

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WorkFlow 4
Like any technology, applying WF requires
understanding
what it is,
why it's useful,
and when it makes sense to use it.

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Isn't WorkFlow Foundation just a visual way to
write code and thus despicable?
What is Windows Workflow Foundation?
A framework for declarative programming
Tools for creating program definitions
A runtime for executing program logic

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DESIGNER DEMO
But first the simplest possible demo
Where we also show that it's possible to add breakpoint ?!

5. WF 4.0 Data Flow Constructs
Arguments
Variables
Expressions
Used to define the way data flows in and out of an
activity.
Used to declare named storage for data within an
activity.
Performs simple operations on arguments to return
a value.
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PURE CODE DEMO

7. WCF Workflow Services
WCF Service
WF Workflow
Client
External
Service
External
Service
WCF endpoint
WCF endpoint
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Benefits
 Long Running Process
 Scalability

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Composability
a workflow can contain flowcharts, state machine, C# code, ...
everything is an activity

10. Challenges
 Work is increasingly distributed
 Coordination code creates complexity
Coordinating messages with application state
Coordinating calls to a database or another service (Async I/O)
Coordinating rainy day scenarios
 Management and tracking of distributed work is difficult
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11. WorkflowServiceHost
Foo
Foo
Foo
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Visual
Visual vocabulary to compose solution makes it easier for non
developers to create

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Tracking

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Integration
SharePoint 2010 uses WF3?
But there is an upcoming book "Professional Workflow 4 in
SharePoint 2010: Real World Business Workflow Solutions "
http://www.amazon.com/Professional-Workflow-SharePoint-
2010-Solutions/dp/0470617888
TFS2010 uses WF4

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Documentation
The business analysis can be mapped directly translated to
workflow/code
There is no distinction between documentation and code
IAB Flowchart on the next slide =>

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Documentation
 Another often used modeling convention is the State Machine

18. Loading Workflow
<Activity x:Class=“Foo" >
<x:Members>
<x:Property Name="argument1“
Type="InArgument(x:String)" />
<x:Property Name="argument2”
Type="InArgument(x:String)" />
</x:Members>
Foo.dll
C# (DynamicActivity)
Activity x =
ActivityXamlServices.Load(xamlFile);
WorkflowInvoker.Invoke(x, new Dictionary … );
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LOAD XAML DEMO
show the xml
load it

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Workflow Service User Model
Operator Commands:
• Suspend, Resume, Terminate and Cancel
Running
Active - In Memory
Idle – Persisted
Suspended
Reason:
• Exception code
• Exception text
Completed
Suspend
Resume
• Successful
Completion
• Terminate
• Cancel
•Terminate
• Cancel

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Persistence / Durability
Windows
Server
AppFabric
Windows
Server
AppFabric
Load
Balancer
Persistence
DB
Workflow
Service
Workflow
Service
Workflow
Management
Service
Workflow
Management
Service Windows
Server
AppFabric
Workflow
Service
Workflow
Management
Service
Instance
123 | data
456 | data
789 | data
011 | data

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Persistence
Persistence lets you pause an instance, save it
somewhere & resume it later
A persisted instance has no affinity to a WF host instance,
CLR instance, thread, process, or machine
Helps with scalability; helps with recovery from failure
WF program instances are serializable
A CLR stack is not serializable, but in a WF program a stack
only exists transiently, during work item execution
Details of persistence are deliberately separate from
the machinery of the WF runtime

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What’s in a Serialized Instance?
A serialized instance contains:
Work item list (empty if instance is idle)
Bookmarks
Data (arg and var values)
•Environments for all executing activity instances
Activity instance info (callbacks, execution props)
Custom data from persistence participants
Does not contain the workflow definition
A million instances can share the same definition
Management of definitions is a host responsibility

24. Workflow Service = WCF + WF
Think "WCF on the outside, WF on the inside“
WCF exposes external interface
WF describes internal flow & state transitions
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Workflow services
WCF Workflow Services
WCF Service
WF Workflow
Client
External
Service
External
Service
WCF endpoint
WCF endpoint

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Content based correlation

27. Some Closing topics
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Server AppFabric
 Most WCF services are hosted in IIS / WAS
 IIS tooling designed for managing web applications
 Windows Server AppFabric = service management
Simplified configuration of services and workflows
Operations dashboard
Workflow service management
GUI and PowerShell tools

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Dashboard

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Server AppFabric
 Health overview provides information about services
Exceptions / completed call count / throttling limits reached
Workflow instances (active / suspended)
Recent history – activations / failures
 Access to workflow information
List of persisted workflows
Tracked workflow data and events
 Tools are based on tool scope (site / application / service)
 Custom queries also possible

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WF State Machine

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PowerShell support
 PowerShell is THE modern scripting environment on Windows
 Most commands and data available as PowerShell cmdlets
 Get and set configuration settings
 Enable application messaging
 Instance management – resume, suspend, terminate
 Combine with other web modules
 Web Administration PowerShell module for managing IIS
 MSDeploy – synch or deploy local or remote services

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hosted designer - MS Research – Trident

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WorkFlow 4
27 August, 2010