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about_Sequence

Sequence

 

SHORT DESCRIPTION

    Describes the Sequence keyword, which runs selected 
    activities sequentially. 
 

LONG DESCRIPTION

    The Sequence keyword runs selected workflow activities  
    sequentially, that is, they run in the order in which  
    they appear and do not run concurrently. The Sequence  
    keyword is valid only in a Windows PowerShell Workflow. 
 
    The Sequence keyword is typically used in a Parallel  
    script block to run selected commands sequentially. 
 
    Because workflow activities run sequentially by default,  
    the Sequence keyword effective only in a Parallel  
    script block. However, it valid outside of a Parallel  
    script block, even if it has no effect. 
 
    The Sequence script block lets you run more commands  
    in parallel by allowing you to run dependent commands 
    sequentially. 
  

SYNTAX

 
   workflow <Verb-Noun> 
   { 
       Sequence 
       { 
         [<Activity>] 
         [<Activity>] 
           ... 
       } 
   } 
 
   workflow <Verb-Noun> 
   { 
       Parallel 
       { 
         [<Activity>] 
         Sequence 
           { 
             [<Activity>] 
             [<Activity>] 
               ... 
           } 
       } 
   } 
 
 
 

DETAILED DESCRIPTION

 
    The commands in a Parallel script block can run concurrently.  
    The order in which they run is not determined. This feature 
    improves the performance of a script workflow. 
 
    You can use a Sequence script block to run selected activities  
    sequentially, even though the activities appear in a Parallel  
    script block. 
  
    The activities in a Sequence script block run one at a time    
    in the order in which they are listed. An activity in a Sequence 
    script block starts only after the previous activity completes. 
     
    However, when the Sequence script block appears in a Parallel 
    script block, the order in which the Sequence script block runs  
    is not determined. It might run before, after, or concurrent with  
    other activities in the Parallel script block. 
 
    For example, the following workflow includes a Parallel script  
    block that runs activities that get processes and services on  
    the computer. The Parallel script block contains a Sequence 
    script block that gets information from a file and uses the 
    information as input to a script.  
 
    The Get-Process, Get-Service and hotfix-related commands  
    are independent of each other and can run concurrently or  
    in any order, but the command that gets the hotfix information 
    must run before the command that uses it. 
 
 
        workflow Test-Workflow 
        { 
            Parallel 
            { 
                 Get-Process 
                 Get-Service 
                                
                 Sequence 
                 { 
                     $Hotfix = Get-Content D:\HotFixes\Required.txt 
                     Foreach ($h in $Hotfix} {D:\Scripts\Verify-Hotfix -Hotfix $h}  
                 } 
            } 
        } 
 
 
 

SEE ALSO

"Writing a Script Workflow" (http://go.microsoft.com/fwlink/?LinkID=262872)
about_ForEach
about_ForEach-Parallel
about_Language_Keywords
about_Parallel
about_Workflows