Using the context object with PowerShell active monitors

Available Monitor Objects and Attributes

PowerShell active monitor scripts have two instantiated session objects available.

• Context. Implementation of the IScriptContext interface. This object provides access to runtime variables and also provides mechanism for returning results to the client. A few useful methods are listed below:
  • object GetProperty(string propertyName) - allows retrieval of context variable values by name.
  • object SetProperty (string propertyName, string propertyValue ) - allows specification of context variable values by name.
  • void SetResult(int resultCode, ResultsString) - allows the script to set a value to indicate success, usually 0 = success and 1 = failure.
• Logger. Implementation of the ILog interface. This object provides the same methods available to C# applications. A few useful methods are listed below:
  • void Error(string message) - Creates an error-specific log entry that includes the message.
  • void Information(string message) - Creates an information-specific log entry that includes the message.
  • void WriteLine(string message) - Creates a generic log entry that includes the message.

Getting or Setting Properties for a Context Object

You can fetch values for context properties using PowerShell active monitor scripts.

Syntax

Property-Value = Context.GetProperty("Property-Name")

Context.SetProperty(" Property-Name "," Property-Value ")

Example

$DeviceIpAddress = $Context.GetProperty("Address")

$Context.SetProperty("Timeout", "180")

Setting Result String and Monitor Status Indicator

The result string you set will be added to the description in the monitor's status change. The status flag you set (0, 1) up/down determines the indicator shown in the State Change Timeline.

# After a successful Get of the deviceIP, Set as result and set success flag ...

$Context.SetResult(0, "Device IP address is: " + $DeviceIpAddress)

Context Object Properties

The following properties can be accessed from the connection object created when running PowerShell Active Monitor Script Syntax Examples.

Context Object Credential Properties

The following credential properties can be set for thePowerShell Active Monitor Script Syntax Examples. These are useful when you need to connect to other services, platforms, or applications after the initial PowerShell connection is made using the active monitor.

Example: Check if Service is Running

Create a PowerShell active monitor that shows status of up only if DNS client is running using stored credentials.

# Device to Poll

$DeviceIpAddress = $Context.GetProperty("Address")

# Set the computer name directly, or...

# $CompName = mydb02.corpnet.example.com (for example)

# ...get it using WMI...

$WmiRes = Invoke-Command -ComputerName $DeviceIpAddress -ScriptBlock { Get-WmiObject Win32_Computersystem }

$CompName = $WMIRes.PSComputerName

# Run command on remote device

$PsResult = Invoke-Command -ComputerName $DeviceName -ScriptBlock { Get-Service | where { $_.Name -match "Dnscache" } }

# Check for condition of 'running'

if ($PsResult.Status -match 'Running') {

$RespondingMessage = "Process '" + $processName + "' running on " + $DeviceIpAddress + " is responding."

$Context.SetResult(0, $RespondingMessage )

} else {

$NotRunningMessage = "Process '" + $processName + "' running on " + $DeviceIpAddress + " is not responding."

$Context.SetResult(1, $NotRunningMessage )

}