Reporting services 2008 R2 web services api - how do I manage security permissions?

Question

I'm writing a powershell script to deploy a number of reports to SQL Server Reporting Services 2008 R2 using the SSRS web services. I'm pretty happy with the approach, it was easy to create a new deployment folder and upload the reports. Following is a snippet of code showing creation of a folder :

$reportServerUri = "http://{0}/ReportServer/ReportService2005.asmx" -f $reportServerName   
$proxy = New-WebServiceProxy -Uri $reportServerUri -Namespace SSRS.ReportingService2005 -Credential $credential
#Dont currently set any properties so set empty array of properties
$propertyArray = @()   
$warnings = $proxy.CreateFolder($folderName, $folderParent, $propertyArray)

However I'd also like to be able to set permissions on the folder and this is where I am a bit stuck. What I want to replicate is where, from the web UI, I would select the security option of the folder and add a user\group against a role.

I thought this might be done through the propertyArray on the createFolder call but I haven't been able to find any information in the docs yet (probed existing properties and can't see anything relevant), I've been looking at http://msdn.microsoft.com/en-us/library/cc282788.aspx for guidance. So reached a dead end there. I thought there might be a specific method to manage permissions at this level but have not been able to identify one.

I am using the ReportingService2005 web services, I know there are also 2010 web services but I havent been able to find what I'm looking for there either.

Does anyone know how I add permissions to folders using the web services api (and presumably a consistent method for other objects like reports and shared data sources)? I assume it must be possible as the web UI allows you to do it. This is not a powershell question but instead about the api's to use to manage permissions.

Update - Below is the snippet of code that seems to do the job. I need to refine this a bit as it looks like the update to policies must include the original list so I need to get the current policies, add my new policy to this and update with the full list. But I'll fix that later!

$Policies = $global:ssrsproxy.GetPolicies($ItemPath, [ref] $InheritsFromParent)   
$PolicyAlreadyExists = $false

$Policies | Foreach-Object{ if ($_.GroupUserName -eq $GroupUserName)    
    {$PolicyAlreadyExists = $true} }
$Policies | Foreach-Object{ $_ | get-member }

    if ($PolicyAlreadyExists){
        "Policy already applied."
    } else {        
        $Policy = New-Object SSRS.ReportingService2005.Policy
        $Policy.GroupUserName = $GroupUserName       
        $Roles = @()   
        $Role = New-Object SSRS.ReportingService2005.Role
        $Role.Name = $RoleName
        $Roles += $Role
        $Policy.Roles = $Roles            

        $global:ssrsproxy.SetPolicies($ItemPath, $Policy)
        "Policy applied."
}           

Answer 1

Use the SetPolicies method. First define an array of Policy(s) containing group/user and required roles, then pass this array to SetPolicies along with the item.