How to use IDirectoryObject

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Introduction

This article will briefly describe how to use the IDirectoryObject in your C++ ADSI application, instead of using the IADs objects intended for scripting clients

Why IDirectoryObject instead of IADs

ADSI (Active Directory Services Interface) is a nice collection of COM objects and gives you easy access to objects and attributes in Active Directory or other LDAP directories. Most programmers use the IADs, IDispatch inherited, interface when programming but using the non-scripting interface IDirectoryObject can improve performance and coding for C++ programmers (if you use scripting languages and/or Visual Basic you have no choice but to use the IADs interface). All ADSI providers must implement the IADs and IDirectoryInterface, so why not take advantage of the features of the IDirectoryObject interface

The major differences between IADs and IDirectoryObject is that the IDirectoryObject will give you direct net access to the directory. IADs uses a property cache from which you read and write attributes using the Get(), get_* and put_* methods and you have to put up with that all the data is delivered using the VARIANT data type. The IDirectoryObject lets you read and write directly through a single request to the object.

Example

Here are three code snippets doing almost the same thing; retrieving the distinguishedName property of a user in Active Directory with a given GUID. The examples can be downloaded above.

IADs

The code in VBScript and in VC++

This first example shows a message box with the distinguishedName and is written in VBScript.

' VBScript (script_example.vbs)

Dim oObject As IADs
Dim vValue As Variant

Set oObject = GetObject("GC://<GUID=b74488fda7dc9c488de9b4bbcdde341f>")
vValue = oObject.Get("distinguishedName")

This example in C++ prints the distinguishedName in a console.

// C++

  IADs* pObject;
  HRESULT hr;
  VARIANT vValue;

  hr = ADsGetObject(CComBSTR(
    L"GC://<GUID=b74488fda7dc9c488de9b4bbcdde341f>"), 
          IID_IADs, 
          (void**)&pObject);
  if(SUCCEEDED(hr)) {
    hr = pObject->Get(CComBSTR(L"distinguishedName"), &vValue);
    if(SUCCEEDED(hr)) {
      
      USES_CONVERSION;
      printf("distinguishedName is %s\n", W2A(vValue.bstrVal));
      VariantClear(&vValue);
    }
    pObject->Release();
  }

IDirectoryObject

This is the same as above but now using the IDirectoryObject. More coding but slightly faster!

  IDirectoryObject* pObject;
  HRESULT hr;
  PADS_ATTR_INFO pAttributeEntries;
  LPWSTR ppAttributeNames[] = {L"distinguishedName"};
  DWORD dwAttributesReturned = 0; 
  hr = ADsGetObject(CComBSTR(
      L"GC://<GUID=b74488fda7dc9c488de9b4bbcdde341f>"), 
          IID_IDirectoryObject, 
          (void**)&pObject);
  if(SUCCEEDED(hr)) {
    hr = pObject->GetObjectAttributes(ppAttributeNames, 
            1, // only one attribute to fetch

            &pAttributeEntries, 
            &dwAttributesReturned );
    if(SUCCEEDED(hr)) {
      if(dwAttributesReturned >0 ) {
        printf("distinguishedName is %S\n", 
            pAttributeEntries->pADsValues[0].CaseIgnoreString);          
      }
      FreeADsMem(pAttributeEntries); // Free up ADSI memory resources

    }
    pObject->Release();
  }

Summary

Use IDirectoryObject when programming in C++ (or plain C), especially if you are reading small or very large amount of attributes of the objects or when reading attributes that the IADs property cache does not cache by default.

Notes

The GUID used in the examples points to a user object in Active Directory, to retrieve the GUID get the objectGUID property of the ADSI object.