Caching mechanisms in PowerShell Universal.
PowerShell Universal provides the ability to use a server-level cache to store data that you use between APIs, Automation and Dashboards. You can configure cache item life times use the
Set-PSUCachecmdlet in any PowerShell script you run in PowerShell Universal. You can also retrieve items from the cache using
Some examples of usages for the cache may be:
- Collecting data with a scheduled job and displaying it within a dashboard
- Collecting data from an API and using it in a job
- Collecting using input from a dashboard and queuing it to run in a scheduled job
To set items in the cache, you can use
Set-PSUCache. Items in the cache are serialized to strings using CLIXML and the PowerShell serializer. When you retrieve objects from the cache, they will no longer be live objects.
Set-PSUCache -Key "CurrentDate" -Value (Get-Date)
There are three types of cache invalidation techniques you can employ.
AbsoluteExpirationparameter defines at what time the item in the cache is invalidated.
The follow example invalidates the cache item after 10 minutes.
Set-PSUCache -Key "CurrentDate" -Value (Get-Date) -AbsoluteExpiration (Get-Date).AddMinutes(10)
AbsoluteExpirationFromNowparameter defines when a cache item is invalidated using a TimeSpan rather than a calculated DateTime.
The following cache item is invalidated 1 hour from now.
Set-PSUCache -Key "CurrentDate" -Value (Get-Date) -AbsoluteExpirationFromNow ([TimeSpan]::FromHours(1))
SlidingExpirationparameter allows you to defines the amount of time before the cache item is invalidated. Each time the cache item is accessed, the timer is reset.
The following cache item will be invalidated in 5 minutes. If it's accessed within those 5 minutes, it will be reset for another 5 minutes.
Set-PSUCache -Key "CurrentDate" -Value (Get-Date) -SlidingExpiration ([TimeSpan]::FromMinutes(5))
You can use the
Get-PSUCachecmdlet to retrieve items from the cache. You simply need to supply the key of the item you wish to retrieve. The deserialized object will be returned from the cmdlet.
Get-PSUCache -Key "CurrentDate"
APIs, Automation scripts and Dashboards all support a $Cache scope. This scope is used to cache data across runspaces that will persist in memory of each of the execution environments. The $Cache scope differs from the server-level cache as it only resides in the execution environment of feature you are using.
For example, if you set a $Cache variable in a dashboard, then it will not be available in an API. This is not true when using the Integrated environment. If a dashboard and API both use the integrated environment, then they share the cache scope.
You can set and retrieve data from the cache scope using variable assignment and retrieval syntax.
$Cache:MyValue = "Hello"