Using the PidTagAdditionalRenEntryIdsEx property in EWS to access localized folders such as the RSS Feeds folder in EWS and Powershell

As I've covered before in this post when you want to access the WellKnowFolders in EWS in a language independent way (eg not having to worry about localization) you can use the WellKnowFoldersName Enumeration in EWS http://msdn.microsoft.com/en-us/library/exchange/microsoft.exchange.webservices.data.wellknownfoldername%28v=exchg.80%29.aspx. Although most of the folderID's are now included in the enumeration one that is missing is the RSS Feeds folder Id.. The Extended property that holds the PR_EntryID for the RSS Feeds Folder is the PidTagAdditionalRenEntryIdsEx extended property on the Non_IPM_Subtree of a mailbox. This Id is held within a PersistData Block which is a structured Binary property that if you want to read in EWS you need to decode (which is fun).

So how do you decode this property the first thing you want to do is convert it to Hex String while you could deal with it in the Binary array I find it easier to deal with as a Hex String.

$hexVal = [System.BitConverter]::ToString($binVal).Replace("-","");

The next thing you need to do is now start parsing the HexString because its a structure Blob you know what to expect so its just a matter of following the Map. So the first thing you need to do is read the first words (2 Bytes). Which tells you what type of Entry your dealing with from this PersistBlockType Values list this is in little-endian format so it needs to be swapped around to make sense.

After that you need to read the next word which contains the length of the Id property (or the payload).  Once you have the length you can then parse the HexEntryId for the folder. As this property stores multiple ID's you need to do this for as many Ids as you can parse out. To then use this HexEntryID in EWS you need to use the ConvertID EWS operation which give you the EWSid of the folder from the HexEntryID which you can then Bind To the folder in EWS.

A full sample of doing this looks like

1. ## Get the Mailbox to Access from the 1st commandline argument  
2.   
3. $MailboxName = $args[0]  
4.   
5. ## Load Managed API dll    
6. Add-Type -Path "C:\Program Files\Microsoft\Exchange\Web Services\1.2\Microsoft.Exchange.WebServices.dll"    
7.     
8. ## Set Exchange Version    
9. $ExchangeVersion = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2010_SP2    
10.     
11. ## Create Exchange Service Object    
12. $service = New-Object Microsoft.Exchange.WebServices.Data.ExchangeService($ExchangeVersion)    
13.     
14. ## Set Credentials to use two options are availible Option1 to use explict credentials or Option 2 use the Default (logged On) credentials    
15.     
16. #Credentials Option 1 using UPN for the windows Account    
17. $psCred = Get-Credential    
18. $creds = New-Object System.Net.NetworkCredential($psCred.UserName.ToString(),$psCred.GetNetworkCredential().password.ToString())    
19. $service.Credentials = $creds        
20.     
21. #Credentials Option 2    
22. #service.UseDefaultCredentials = $true    
23.     
24. ## Choose to ignore any SSL Warning issues caused by Self Signed Certificates    
25.     
26. ## Code From http://poshcode.org/624  
27. ## Create a compilation environment  
28. $Provider=New-Object Microsoft.CSharp.CSharpCodeProvider  
29. $Compiler=$Provider.CreateCompiler()  
30. $Params=New-Object System.CodeDom.Compiler.CompilerParameters  
31. $Params.GenerateExecutable=$False  
32. $Params.GenerateInMemory=$True  
33. $Params.IncludeDebugInformation=$False  
34. $Params.ReferencedAssemblies.Add("System.DLL") | Out-Null  
35.   
36. $TASource=@' 
37.   namespace Local.ToolkitExtensions.Net.CertificatePolicy{ 
38.     public class TrustAll : System.Net.ICertificatePolicy { 
39.       public TrustAll() {  
40.       } 
41.       public bool CheckValidationResult(System.Net.ServicePoint sp, 
42.         System.Security.Cryptography.X509Certificates.X509Certificate cert,  
43.         System.Net.WebRequest req, int problem) { 
44.         return true; 
45.       } 
46.     } 
47.   } 
48. '@   
49. $TAResults=$Provider.CompileAssemblyFromSource($Params,$TASource)  
50. $TAAssembly=$TAResults.CompiledAssembly  
51.   
52. ## We now create an instance of the TrustAll and attach it to the ServicePointManager  
53. $TrustAll=$TAAssembly.CreateInstance("Local.ToolkitExtensions.Net.CertificatePolicy.TrustAll")  
54. [System.Net.ServicePointManager]::CertificatePolicy=$TrustAll  
55.   
56. ## end code from http://poshcode.org/624  
57.     
58. ## Set the URL of the CAS (Client Access Server) to use two options are availbe to use Autodiscover to find the CAS URL or Hardcode the CAS to use    
59.     
60. #CAS URL Option 1 Autodiscover    
61. $service.AutodiscoverUrl($MailboxName,{$true})    
62. "Using CAS Server : " + $Service.url     
63.      
64. #CAS URL Option 2 Hardcoded    
65.     
66. #$uri=[system.URI] "https://casservername/ews/exchange.asmx"    
67. #$service.Url = $uri      
68.     
69. ## Optional section for Exchange Impersonation    
70.     
71. #$service.ImpersonatedUserId = new-object Microsoft.Exchange.WebServices.Data.ImpersonatedUserId([Microsoft.Exchange.WebServices.Data.ConnectingIdType]::SmtpAddress, $MailboxName)   
72. $PidTagAdditionalRenEntryIdsEx = new-object Microsoft.Exchange.WebServices.Data.ExtendedPropertyDefinition(0x36D9, [Microsoft.Exchange.WebServices.Data.MapiPropertyType]::Binary)  
73. $psPropset = new-object Microsoft.Exchange.WebServices.Data.PropertySet([Microsoft.Exchange.WebServices.Data.BasePropertySet]::FirstClassProperties)  
74. $psPropset.Add($PidTagAdditionalRenEntryIdsEx)  
75.   
76. # Bind to the NON_IPM_ROOT Root folder    
77. $folderid= new-object Microsoft.Exchange.WebServices.Data.FolderId([Microsoft.Exchange.WebServices.Data.WellKnownFolderName]::Root,$MailboxName)     
78. $NON_IPM_ROOT = [Microsoft.Exchange.WebServices.Data.Folder]::Bind($service,$folderid,$psPropset)  
79. $binVal = $null;  
80. $AdditionalRenEntryIdsExCol = @{}  
81. if($NON_IPM_ROOT.TryGetProperty($PidTagAdditionalRenEntryIdsEx,[ref]$binVal)){  
82.     $hexVal = [System.BitConverter]::ToString($binVal).Replace("-","");  
83.     ##Parse Binary Value first word is Value type Second word is the Length of the Entry  
84.     $Sval = 0;  
85.     while(($Sval+8) -lt $hexVal.Length){  
86.         $PtypeVal = $hexVal.SubString($Sval,4)  
87.         $PtypeVal = $PtypeVal.SubString(2,2) + $PtypeVal.SubString(0,2)  
88.         $Sval +=12;  
89.         $PropLengthVal = $hexVal.SubString($Sval,4)  
90.         $PropLengthVal = $PropLengthVal.SubString(2,2) + $PropLengthVal.SubString(0,2)  
91.         $PropLength = [Convert]::ToInt64($PropLengthVal, 16)  
92.         $Sval +=4;  
93.         $ProdIdEntry = $hexVal.SubString($Sval,($PropLength*2))  
94.         $Sval += ($PropLength*2)  
95.         $PtypeVal + " : " + $ProdIdEntry  
96.         $AdditionalRenEntryIdsExCol.Add($PtypeVal,$ProdIdEntry)   
97.     }     
98. }  
99.   
100. function ConvertFolderid($hexId){  
101.     $aiItem = New-Object Microsoft.Exchange.WebServices.Data.AlternateId    
102.     $aiItem.Mailbox = $MailboxName    
103.     $aiItem.UniqueId = $hexId  
104.     $aiItem.Format = [Microsoft.Exchange.WebServices.Data.IdFormat]::HexEntryId;    
105.     return $service.ConvertId($aiItem, [Microsoft.Exchange.WebServices.Data.IdFormat]::EWSId)   
106. }  
107.   
108. if($AdditionalRenEntryIdsExCol.ContainsKey("8001")){  
109.     $siId = ConvertFolderid($AdditionalRenEntryIdsExCol["8001"])  
110.     $RSSFolderID = new-object Microsoft.Exchange.WebServices.Data.FolderId($siId.UniqueId.ToString())  
111.     $RSSFolder = [Microsoft.Exchange.WebServices.Data.Folder]::Bind($service,$RSSFolderID)  
112.     $RSSFolder  
113. }