Connecting to a running instance of Internet Explorer

There are some methods to connect to a running instance of IE. This one is how to connect through the ROT (Running Object Table).

Usually, an application connects to a running instance of another application using the Running Object table. However the Internet Explorer 4.0 doesn't not register itself in ROT. The solution is to write so-called "Browser Helper Object" – a tiny COM object that exposes IObjectWithSite interface and register itself in the ROT. Also it's necessary to register this object in the Registry under the following key:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\ 

The Internet Explorer will create new instance of each Browser Helper Object listed in registry every time new instance of Internet Expoler is started.

HKLM\SOFTWARE\Microsoft\Windows
       \CurrentVersion\Explorer\Browser Helper Objects\{CE7C3CF0-4B15- 11D1-ABED-709549C10000} 

The following code demonstrates how to allow multiple instances of the Internet Explorer to be registered in the ROT using item moniker.

/////////////////////////////////////////////////////////////////////////////  IEHELPER.H
#ifndef __IEHELPER_H_
#define __IEHELPER_H_

#include "resource.h"       // main symbols

/////////////////////////////////////////////////////////////////////////////
// CIEHelper
class CIEHelper : 
        public CComObjectRootEx<CComSingleThreadModel>,
        public CComCoClass<CIEHelper, &CLSID_IEHelper>,
        public IObjectWithSiteImpl<CIEHelper>,
        public IIEHelper
{
public:
        CIEHelper()
        {
                m_dwROTID = 0;
        }

       ~CIEHelper()
        {
        }

        // IObjectWithSite interface
        STDMETHOD(SetSite)(IUnknown* pUnkSite);

DECLARE_REGISTRY_RESOURCEID(IDR_IEHELPER)

BEGIN_COM_MAP(CIEHelper)
        COM_INTERFACE_ENTRY(IIEHelper)
        COM_INTERFACE_ENTRY(IObjectWithSite)
END_COM_MAP()

// IIEHelper
public:
        void SetROTID(DWORD dwValue)
        {
                m_dwROTID = dwValue;
        }
private:
        DWORD m_dwROTID;
        void ROT_UnRegister();
        void ROT_Register();
};

#endif //__IEHELPER_H_

/////////////////////////////////////////////////////////////////// IEHELPER.CPP
// IEHelper.cpp : Implementation of CIEHelper

#include "stdafx.h"
#include "IE.h"
#include "IEHelper.h"

#include <initguid.h>
#include <exdisp.h>        // the IID_IWebBrowser is located over there
#include <stdio.h>

/////////////////////////////////////////////////////////////////////////////
// CIEHelper
//

// CObjectWithSite Methods
//

STDMETHODIMP CIEHelper::SetSite(IUnknown* pUnkSite)
{
        USES_CONVERSION;

        // remove previously registered object from the table
        ROT_UnRegister();

        // neccessary initialization
        HRESULT hResult = IObjectWithSiteImpl<CIEHelper>::SetSite(pUnkSite);

        // register helper object in the running object table
        ROT_Register();

        return hResult;
}

///////////////////////////////////////////////////////////////////////////
//

//
// Private Section
//

const static TCHAR* szMonikerTemplateName = _T("Browser Helper Object");

//
// register the object in the running object table 
//

void CIEHelper::ROT_Register()
{
        CComPtr<IRunningObjectTable> pTable;
        if(GetRunningObjectTable(0, &pTable) == S_OK)
        {
                CComBSTR bstrItemName;
                CComPtr<IMoniker> pMoniker;
                TCHAR szBuffer[1024];

                sprintf(szBuffer, "%s | %d", szMonikerTemplateName, m_spUnkSite);
                bstrItemName = szBuffer;
                if(CreateItemMoniker(NULL, bstrItemName, &pMoniker) == S_OK)
                {
                        DWORD dwRegister;
                        if(pTable->Register(1, (IUnknown*)this, pMoniker, &dwRegister) == S_OK)
                        {
                                SetROTID(dwRegister);
                                ATLTRACE("IIEHelper: the moniker %s has been registered successfully\n", szBuffer);
                        }
                        else
                        {
                                ATLTRACE("IIEHelper: failed to register moniker % s in the ROT\n", szBuffer);
                        }
                }
                else
                {
                        ATLTRACE("IIEHelper: failed to create moniker %s\n", szBuffer);
                }
        }
        else
        {
                ATLTRACE("IIEHelper: Could not retrieve the ROT pointer\n");
        }
}

void CIEHelper::ROT_UnRegister()
{
        CComPtr<IRunningObjectTable> pTable;
        if(GetRunningObjectTable(0, &pTable) == S_OK)
        {
                HRESULT hRes = pTable->Revoke(m_dwROTID);
                ATLTRACE("IIEHelper: ID = %d, result code %x\n", m_dwROTID, hRes);
        }
        SetROTID(0);
}

////////////////////////////////////////////////////////////////////// IEHELPER.RGS
// The following lines should be included into the self-registration portion of 
// COM application.

...

HKLM
{
        SOFTWARE
        {
                Microsoft
                {
                        Windows
                        {
                                CurrentVersion
                                {
                                        Explorer
                                        {
                                                'Browser Helper Objects'
                                                {
                                                        <CLSID>
                                                }
                                        }
                                }
                        }
                }
        }
}

Having implemented and registered the Browser Helper, an application can now obtain the pointer to a running instance of IE by traversing the ROT.

The following example shows the rough method I used to list the instances of IE:

IRunningObjectTable* pTable;

if(!FAILED(GetRunningObjectTable(0, &pTable)))
{
        IEnumMoniker* pEnum;
        if(!FAILED(pTable->EnumRunning(&pEnum)))
        {
                IUnknown* pUnknown;
                IMoniker* pCurMoniker = NULL;
                LPMALLOC pMalloc;
                while (pEnum->Next(1, &pCurMoniker, NULL) == S_OK) 
                {
                        if(!FAILED(pTable->GetObject(pCurMoniker, &pUnknown)))
                        {
                                IObjectWithSite* pSite;
                                if(!FAILED(pUnknown->QueryInterface(IID_IObjectWithSite, (void**)&pSite)))
                                {
                                        IDispatch* pDispatch;
                                        if(pSite->GetSite(IID_IDispatch, (void**)&pDispatch) == S_OK)
                                        {
                                                CWebBrowserApp browser;
                                             
                                                browser.AttachDispatch(pDispatch);
                                                TRACE("LocationURL: %s\n", browser.GetLocationURL());
                                                        TRACE("LocationName: %s\n", browser.GetLocationName());
                                                browser.DetachDispatch();
                                                pDispatch->Release();
                                        }
                                        pSite->Release();
                                }
                                pUnknown->Release();
                        }
                        pCurMoniker->Release();
                }
                pEnum->Release();
        }
        pTable->Release();
}

MORE INFORMATION

The following file is available for download from the Microsoft Software Library:

 ~ IEHelper.exe (size: 39958 bytes) 

Date Posted: December 13, 1998