type Resource =
| VM of VMResource
| Unit of UnitResource

type VMResource = {
    ComputerName: string
    Ip: string
    Attributes: string[]
}

type UnitResource = {
    UnitName: string
    Ip: string
    Username: string
    Password: string
    Attributes: string[]
}

Add-Type -Path "pathtomydll.dll"

$fullRequestUrl = "http://localhost:2121/Resources/Get"
$body = "{`"Id`":`"Test`",`"RequestedResources`":[{`"ResourceType`":{`"Case`":`"VM`"},`"Attributes`":[`"A1`",`"A2`"]},{`"ResourceType`":{`"Case`":`"Unit`"},`"Attributes`":[]}]}"

$resp = Invoke-WebRequest $fullRequestUrl -Method Post -Body $body -ContentType "application/json"
$obj = [ServerProtocolTypes+GetResourcesResponse]::FromJson($resp)
$obj.GetType() # GetResourcesResponse

Add-Type -Path "pathtomydll.dll"

$fullRequestUrl = "http://localhost:2121/Resources/Get"
$body = "{`"Id`":`"Test`",`"RequestedResources`":[{`"ResourceType`":{`"Case`":`"VM`"},`"Attributes`":[`"A1`",`"A2`"]},{`"ResourceType`":{`"Case`":`"Unit`"},`"Attributes`":[]}]}"

$job = Start-Job -ScriptBlock { param($url, $reqBody) Add-Type -Path "pathtomydll.dll"; $resp = Invoke-WebRequest $url -Method Post -Body $reqBody -ContentType "application/json"; return [ServerProtocolTypes+GetResourcesResponse]::FromJson($resp) } -ArgumentList ($fullRequestUrl, $body)
Wait-Job $job
$obj = Receive-Job $job
$obj.GetType() # PSObject