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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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