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PowerShell 3.0 Workflows

Ravikanth Chaganti

PowerShell Bangalore User Group (@PSBUG) – 15th December, 2012

http://twitter.com/ravikanth

http://ravichaganti.com/blog

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About Me• Work at Dell Inc.• PowerShell MVP since

2010• Author

• Layman’s guide to PS remoting

• WQL via PowerShell

• Founder & Editor• PowerShellMagazine.c

om• LearningPowerShell.c

om (coming soon)

LearningPowerShell.comImage courtesy: http://ebsindy.com/wp-content/uploads/2012/05/web-pg-1-br-pg-1.jpg

PS Workflows

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Introduction to Workflows

#Test Computer Connectivity$computers = Get-Content computers.txt$computers.CountMeasure-Command -Expression { foreach ($computer in $computers) { Test-Connection -ComputerName $computer -Count 1 -EA SilentlyContinue }}

Let us start with an example!

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Introduction to Workflows

• Simple example but can be a long-running task!• How can we make this:• Repeatable• Parallelizable• Interruptible• Stoppable and Restartable

We can use functions, remoting, and background jobs to achieve all the above!Involves lot of scripting!

Workflows in PowerShell 3.0 is introduced to ease this task!

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Introduction to Workflows

• A Workflow is a set of activities• An activity is a specific task in a

Workflow• Scalable solutions for complex

activities– Run in parallel or sequentially– Repeatable– Interruptible and recoverable

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Introduction to Workflows

• PowerShell Workflows are based on Windows Workflow Foundation (WWF)

• Can be authored using – PowerShell syntax– XAML files (Visual Studio)

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Benefits of Workflows

• Multi-device management• Automated failure recovery• Connection and activity retries• Connect and disconnect• Task Scheduling

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Workflow Environment

Source: http://technet.microsoft.com/en-us/library/jj134257.aspx

Workflow ClientComputer used for managing or viewing workflows

Workflow ServerComputer used for running workflows

Managed NodeComputer on which actions or activities are performed

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Writing a Workflow

Workflow Write-Hello {“Hello, World”

}

• Syntactically similar to PowerShell Functions

• Can define parameters & CmdletBinding attribute• No Begin, Process, and End blocks!

• Most of the core cmdlets can be added as cmdlets

• Other cmdlets implicitly run as InlineScript

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Writing a Workflowworkflow Test-Workflow{

Get-Process -Name PowerShellGet-WindowsFeature -Name PowerShell, PowerShell-v2InlineScript { Get-Variable -Name PSHome }

}

InlineScript activity is used for cmdlets that have no workflow activity implementation or for the dynamic parameters!workflow Test-Workflow{

InlineScript {Get-ChildItem -Path Cert:\CurrentUser -CodeSigningCert}}

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Activities in Parallel

workflow Test-Workflow{

Parallel{

<Activity><Activity>

}}

Foreach –Parallel and Parallel Keywords are used

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Activities in Sequence

workflow Test-Workflow{

sequence{

<Activity3><Activity4>...

}}

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Nested Workflows

• Workflows can be nested and combined with functions!– Increases complexity

• Recursive calling is not allowed

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Quick Bytes on benefits

• Suspend / Resume Workflows• Restart computer in a workflow–Manual– Automatic resume using Scheduled Jobs

• Checkpoints or persisting workflow data

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References

• Getting Started with Windows PowerShell Workflows: http://technet.microsoft.com/en-us/library/jj134242

• Windows Workflows (video) by Bruce Payette: http://youtu.be/qeV4Qmce2Dk

• PowerShell Team Blog:– http://

blogs.msdn.com/b/powershell/archive/2012/03/17/when-windows-powershell-met-workflow.aspx

– http://blogs.msdn.com/b/powershell/archive/2012/06/15/high-level-architecture-of-windows-powershell-workflow-part-1.aspx

– http://blogs.msdn.com/b/powershell/archive/2012/06/19/high-level-architecture-of-windows-powershell-workflow-part-2.aspx

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