Difference between revisions of "PowerShell API Wrapper Tutorial"

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==== Cancelling Asynchronous API Wrapper PowerShell Jobs ====
 
==== Cancelling Asynchronous API Wrapper PowerShell Jobs ====
To cancel the execution of an asynchronous API command, use ''cancel-async'' with the asynchronous command's token as a parameter. For the example above the call would be:
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To cancel the execution of an asynchronous API command, use ''Stop-MSApiCall'' with either the token or the "JOB" return object. For the example above the call would be:
  
 
<source lang="powershell" smart-tabs="true" toolbar="false" gutter="false">
 
<source lang="powershell" smart-tabs="true" toolbar="false" gutter="false">
   Invoke-MSApiCall $MSApiclient "cancel-async" @{token = $return.Token}
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   Stop-MSApiCall $MSApiclient -AsyncReturnObject $return
 
</source>
 
</source>

Revision as of 12:48, 29 August 2014

This tutorial aims to explain the usage of the MailStore Service Provider Edition Management API through simple Windows PowerShell example scripts. Basic knowledge of MailStore SPE, Windows and PowerShell is a necessary precondition.

The API wrapper used in this tutorial is an example implementation of a MailStore SPE Management API client. As communication with the Management API is done via web requests, it is possible to create different implementations that use the corresponding PowerShell cmdlets. However, such implementations are out of scope of this tutorial.

Please note: It is strongly recommended to use a non-productive test environment for this tutorial as well as for script development in general, in order to prevent loss of data or other problems.

Installation of Necessary Components

The examples demonstrated here use the MailStore PowerShell API Wrapper and are compatible with Windows PowerShell 3.0 and higher. Depending on your version of Windows it might be necessary to download and install a compatible version of PowerShell first. You can find the components necessary for this tutorial here:

Please take note of the system requirements and further notices for the respective version of the Windows Management Framework.

Important Notice: Installation of a Windows Management Framework on systems that require a specific version of Windows PowerShell, such as Microsoft Exchange Servers, is not supported and may lead to massive system failures and data loss.

After downloading and installing Windows PowerShell (if necessary) please unzip the MailStore PowerShell API Wrapper and the example scripts (to C:\MailStore SPE Scripting Tutorial\PowerShell\ by default).

Neither the MailStore PowerShell API Wrapper nor the example scripts are digitally signed, therefore execution of such scripts has to be enabled in an administrative PowerShell session using

  Set-ExecutionPolicy -ExecutionPolicy Unrestricted

Importing the MailStore PowerShell API Wrapper

The MailStore PowerShell API Wrapper is implemented as a PowerShell Script Module (MS.PS.Lib.psm1) and can thus be imported in a PowerShell session via its manifest (MS.PS.Lib.psd1) by using Import-Module.

Please open a PowerShell session and import the API wrapper module using this command:

  Import-Module "C:\MailStore SPE Scripting Tutorial\PowerShell\API-Wrapper\MS.PS.Lib.psd1"

Getting Information about the MailStore PowerShell API Wrapper

The MailStore PowerShell API Wrapper provides several functions to access the MailStore SPE Management API, following PowerShell conventions. Enter the following command to get information about these features:

  Get-Module MS.PS.Lib | fl

More detailed information is available via the module's properties. For example,

  (Get-Module MS.PS.Lib).ExportedFunctions

returns the functions provided by the module. Via

  Get-Help *MSApi*

the MailStore PowerShell API Wrapper returns inline help for all its functions.

Calling API Wrapper Functions

The following example script (Example1.ps1 in the tutorial package) explains the basic usage of MailStore PowerShell API Wrapper functions.

  Import-Module '..\API-Wrapper\MS.PS.Lib.psd1'
  $MSApiClient = New-MSApiClient -Username "admin" -Password "admin" -ManagementServer "localhost" -Port 8474 -IgnoreInvalidSSLCerts
  $return = Invoke-MSApiCall $MSApiClient "GetEnvironmentInfo"
  $return.Data.result | fl

The function New-MSApiClient creates a new API client object which the Invoke-MSApiCall function uses for API calls. The values for -Username and -Password have to be supplied, while -ManagementServer defaults to "localhost" and -Port defaults to "8474". The switch -IgnoreInvalidSSLCerts has to be set if untrusted certificates are used; otherwise an error occurs.

Apart from the API client object, Invoke-MSApiCall needs an API command and its parameters if applicable. The command GetEnvironmentInfo in the script does not have any parameters and returns an object as follows:

 Type  : JSON
 Token : 
 Data  : @{error=; token=; statusVersion=2; statusCode=succeeded; percentProgress=; statusText=; result=; logOutput=}

The object's Type property has the value "JSON" for synchronous API commands or "JOB" for asynchronous API commands (see below); it characterizes the type of the object contained in the Data property. The Token property is only relevant for asynchronous API commands.

The Data property contains a JSON status object returned by MailStore SPE:

 error           : 
 token           : 
 statusVersion   : 2
 statusCode      : succeeded
 percentProgress : 
 statusText      : 
 result          : @{version=9.0.3.9845; copyright=Copyright (c) 2005-2014 MailStore Software GmbH; licenseeName=MailStore; licenseeID=23634; serverName=tutorial.mailstore.test; userName=admin; systemProperties=}
 logOutput       :  

The result property of that object has the actual return value if the request succeeded as indicated by the statusCode:

 version          : 9.0.3.9845
 copyright        : Copyright (c) 2005-2014 MailStore Software GmbH
 licenseeName     : MailStore Software GmbH
 licenseeID       : 23634
 serverName       : tutorial.mailstore.test
 userName         : admin
 systemProperties : @{processors=System.Object[]; totalPhysicalMemory=2146947072; operatingSystem=Microsoft Windows Server 2012 Standard}
 

Calling API Wrapper Functions with Parameters

For most MailStore SPE Management API commands you need to provide parameters. Of course, the MailStore PowerShell API Wrapper's Invoke-MSApiCall function can submit these parameters, as demonstrated by the following script (Example2.ps1 in the tutorial package):

  Import-Module '..\API-Wrapper\MS.PS.Lib.psd1'
  $MSApiclient = New-MSApiClient -Username "admin" -Password "admin" -ManagementServer "localhost" -Port 8474 -IgnoreInvalidSSLCerts
  $return = (Invoke-MSApiCall $MSApiclient "GetInstances" @{instanceFilter = "*"})
  if ($return.Type -eq "JOB") {
      Wait-Job $return.Data
      $instances = (Receive-Job $return.Data).Data.result
  } else {
      $instances = $return.Data.result
  }
  foreach ($instance in $instances) {
      $users = (Invoke-MSApiCall $MSapiclient "GetUsers" @{instanceID = $instance.instanceID}).Data.result
      foreach ($user in $users) {
          (Invoke-MSApiCall $MSapiclient "GetUserInfo" @{instanceID = $instance.instanceID; userName = $user.userName}).Data.result | fl
      }
  }

The scripts lists details about the users created in a MailStore SPE instance. Because the MailStore PowerShell API Wrapper converts API responses into objects, their properties can be used directly in the script's workflow. The function Invoke-MSApiCall expects parameters as a hashtable, e.g. @{parametername1 = value1; parametername2 = value2;...}. Parameter names are case sensitive.

First, a list of all MailStore SPE instances is requested with the API command GetInstances. In case of many instances this command could be executed asynchronously by the server and return a job object (see below) otherwise an array of instances as follows is returned:

 instanceID     : test01
 alias          : tutorial
 displayName    : Tutorial Test Instance
 instanceHost   : tutorial.mailstore.test
 startMode      : automatic
 processID      : 3140
 status         : running
 startStopError : 

The script now iterates over this array using the instanceID property of each entry as a parameter for the API command GetUsers. The list of users of each instance is then also iterated over and each user's properties are requested via GetUserInfo:

For the entry listed above the result could be as follows:

 userName            : johndoe
 fullName            : John Doe
 distinguishedName   : 
 authentication      : integrated
 emailAddresses      : {}
 pop3UserNames       : {}
 privileges          : {login, changePassword}
 privilegesOnFolders : {@{folder=johndoe; privileges=System.Object[]}}

As can be seen in the privilegesOnFolders property, returned objects may be nested and may also contain further objects.

Handling Asynchronous API Calls

The server may decide to execute Management API commands asynchronously if their execution may take more time. The MailStore PowerShell API Wrapper identifies calls of such asynchronously executed API commands and executes them as PowerShell Jobs in the background.

Processing API Wrapper PowerShell Jobs Synchronously

A script's execution can be interrupted until a PowerShell Job created by the API wrapper terminates as demonstrated by the following script (Example3.ps1 in the tutorial package):

  Import-Module '..\API-Wrapper\MS.PS.Lib.psd1'
  $MSApiclient = New-MSApiClient -Username "admin" -Password "admin" -ManagementServer "localhost" -Port 8474 -IgnoreInvalidSSLCerts
  $return = (Invoke-MSApiCall $MSApiclient "GetInstances" @{instanceFilter = "*"})
  if ($return.Type -eq "JOB") {
      Wait-Job $return.Data
      $instances = (Receive-Job $return.Data).Data.result
  } else {
      $instances = $return.Data.result
  }
  $return = Invoke-MSApiCall $MSApiclient "VerifyStore" @{instanceID = $instances[0].instanceID; id = "1"}
  if ($return.Type -eq "JOB") {
      Wait-Job $return.Data
      Receive-Job $return.Data
  } else {
      $return.Data
  }

The API commands GetInstances and VerifyStore called in the script regularly return objects with the Type property "JOB".

 Type  : JOB
 Token : sa90edf0029de319e62e856aeb47678325
 Data  : System.Management.Automation.PSRemotingJob

The Token property now contains a unique ID returned by the server that identifies the server process; it is important for event handling (see below). The Data property contains the PowerShell Job which processes the status objects returned by the server in the background.

This PowerShell Job monitors the status of its corresponding server process and is terminated when that process is finished. Through the PowerShell cmdlet Wait-Job the scripts waits until the job has been completed, getting the job's results through Receive-Job:

 Type       : JSON
 Token      : 
 Data       : @{error=; token=sa90edf0029de319e62e856aeb47678325; statusVersion=32; statusCode=succeeded; percentProgress=100; statusText=; result=; logOutput=}
 RunspaceId : 451b5d8b-dcc3-4eec-820e-3dbd2bcb4c5f

Please note: The RunspaceId is generated by the PowerShell automatically and can be ignored here.

Processing API Wrapper PowerShell Jobs Asynchronously

Instead of interrupting a script's execution, the PowerShell Jobs created by the API wrapper can be reacted to while they are running in the background. These jobs trigger a PowerShell EngineEvent with each status request that the script can subscribe to execute further code on each occurrence. To demonstrate this, the previous script needs to be adapted only a bit (Example4.ps1 in the tutorial package):

  Import-Module '..\API-Wrapper\MS.PS.Lib.psd1'
  $MSApiclient = New-MSApiClient -Username "admin" -Password "admin" -ManagementServer "localhost" -Port 8474 -IgnoreInvalidSSLCerts
  $return = (Invoke-MSApiCall $MSApiclient "GetInstances" @{instanceFilter = "*"})
  if ($return.Type -eq "JOB") {
      Wait-Job $return.Data
      $instances = (Receive-Job $return.Data).Data.result
  } else {
      $instances = $return.Data.result
  }
  $return = Invoke-MSApiCall $MSApiclient "VerifyStore" @{instanceID = $instances[0].instanceID; id = "1"}
  if ($return.Type -eq "JOB") {
      $mssevent = Register-EngineEvent -SourceIdentifier $return.Token -Action {write-host $event.MessageData.Data}
  } else {
      $return.Data
  }

Here the script subscribes to the event that is triggered by the background job via Register-EngineEvent, using the return object's Token property as SourceIdentifier. By that property the event relates to the triggering PowerShell Job and thus to the server process. The Action script block is itself created as a PowerShell Job that is executed with each triggering of the event. Through the MessageData property of the $event automatic variable the script block can access the return object provided by the background job. That object's Data property contains the status of the server process:

 @{error=; token=sae8b8eaa3f645d11ee0207797cebbc0b1; statusVersion=8;
   statusCode=running; percentProgress=1; statusText=; result=;
   logOutput=  300 messages verified...
  }

Via these mechanisms the script can execute further tasks while monitoring the server process in the background. Execution and handling of multiple asynchronous API commands is also possible this way.

Cancelling Asynchronous API Wrapper PowerShell Jobs

To cancel the execution of an asynchronous API command, use Stop-MSApiCall with either the token or the "JOB" return object. For the example above the call would be:

  Stop-MSApiCall $MSApiclient -AsyncReturnObject $return