IE Extension: CSIEDownloadManager


The sample demonstrates how to implement a custom download manager for IE.
When IE starts to download a file, the CSWebDownloader.exe will be launched to
download the file.

NOTE: Some third party download extensions for IE may conflict with this code sample,
     so it is better to disable them temporarily before you try out the sample.

Setup and Removal:

A. Setup

For 32bit IE on x86 or x64 OS, install CSIEDownloadManagerSetup(x86).msi, the output
of the CSIEDownloadManagerSetup(x86) setup project.

For 64bit IE on x64 OS, install CSIEDownloadManagerSetup(x64).msi outputted by the
CSIEDownloadManagerSetup(x64) setup project.

B. Removal

For 32bit IE on x86 or x64 OS, uninstall CSIEDownloadManagerSetup(x86).msi, the
output of the CSIEDownloadManagerSetup(x86) setup project.

For 64bit IE on x64 OS, uninstall CSIEDownloadManagerSetup(x64).msi, the output of
the CSIEDownloadManagerSetup(x64) setup project.


Step1. Open this project in VS2010 and set the platform of the solution to x86. Make
      sure that the projects CSIEDownloadManagerSetup, CSWebDownloader and
      CSIEDownloadManagerSetup(x86) are selected to build in Configuration Manager.

       NOTE: If you want to run this sample in 64bit IE, set the platform to x64 and
             select CSIEDownloadManagerSetup, CSWebDownloader and
            CSIEDownloadManagerSetup(x64) to build.
Step2. Build the solution.

Step3. Right click the project CSIEDownloadManagerSetup(x86) in Solution Explorer,
      and choose "Install".

Step4. Open 32bit IE and visit the the download link of Microsoft .NET Framework 4
      Click the "Download" button on this page, and then CSWebDownloader.exe will
      be launched. In CSWebDownloader.exe, you will find that the url is
      and the local path is D:\dotNetFx40_Full_x86_x64.exe

Step5. Click the button "Download" in CSWebDownloader.exe, it will start to download
      the file, and after a few minutes, you will find a file D:\dotNetFx40_Full_x86_x64.exe
      in Windows Explorer.

Code Logic:

A. Create the CSWebDownloader project with following features:
  1. Set the buffer and cache size.
  2. Download a specified block data of the whole file.
  3. Start, Pause, Resume and Cancel a download.  
  4. Supply the file size, download speed and used time.
  5. Expose the events StatusChanged, DownloadProgressChanged and DownloadCompleted.
  6. Can be launched with an argument (the file to download).

  For more detailed information about the CSWebDownloader.exe, see

B. Create the CSIEDownloadManager project.

  In Visual Studio 2010, create a Visual C# / Windows / Class Library project
  named "CSIEDownloadManager".
  The ability to implement a custom download manager was introduced in Microsoft
  Internet Explorer 5.5. This feature enables you to extend the functionality of
  Windows Internet Explorer and WebBrowser applications by implementing a Component
  Object Model (COM) object to handle the file download process.
  A download manager is implemented as a COM object that exposes the IUnknown and
  IDownloadManager interface. IDownloadManager has only one method,
  IDownloadManager::Download, which is called by Internet Explorer or a WebBrowser
  application to download a file.
  For Internet Explorer 6 and later, if the WebBrowser application does not implement
  the IServiceProvider::QueryService method, or when using Internet Explorer itself
  for which IServiceProvider::QueryService cannot be implemented, the application
  checks for the presence of a registry key containing the class identifier (CLSID)
  of the download manager COM object. The CLSID can be provided in either of the
  following registry values.
                     Internet Explorer
                     Internet Explorer
  DownloadUI is not a key, it is a REG_SZ value under Software\Microsoft\Internet Explorer.
  If the application cannot locate a custom download manager the default download user
  interface is used.
  The IEDownloadManager class implements the IDownloadManager interface. When IE starts to
  download a file, the Download method of this class will be called, and then the
  CSWebDownloader.exe will be launched to download the file.

       public int Download(IMoniker pmk, IBindCtx pbc, uint dwBindVerb, int grfBINDF,
           IntPtr pBindInfo, string pszHeaders, string pszRedir, uint uiCP)

           // Get the display name of the pointer to an IMoniker interface that specifies
           // the object to be downloaded.
           string name = string.Empty;
           pmk.GetDisplayName(pbc, null, out name);

           if (!string.IsNullOrEmpty(name))
               Uri url = null;
               bool result = Uri.TryCreate(name, UriKind.Absolute, out url);

               if (result)

                   // Launch CSWebDownloader.exe to download the file.
                   FileInfo assemblyFile =
                       new FileInfo(Assembly.GetExecutingAssembly().Location);
                   ProcessStartInfo start = new ProcessStartInfo
                       Arguments = name,
                       FileName =
                       string.Format("{0}\\CSWebDownloader.exe", assemblyFile.DirectoryName)
                   return 0;
           return 1;
  This class will also set the registry values when this assembly is registered to COM.
       /// <summary>
       /// Called when derived class is registered as a COM server.
       /// </summary>
       public static void Register(Type t)
           string ieKeyPath = @"SOFTWARE\Microsoft\Internet Explorer\";
           using (RegistryKey ieKey = Registry.LocalMachine.CreateSubKey(ieKeyPath))
               ieKey.SetValue("DownloadUI", t.GUID.ToString("B"));

       /// <summary>
       /// Called when derived class is unregistered as a COM server.
       /// </summary>
       public static void Unregister(Type t)
           string ieKeyPath = @"SOFTWARE\Microsoft\Internet Explorer\";
           using (RegistryKey ieKey = Registry.LocalMachine.OpenSubKey(ieKeyPath, true))

C. Deploying the IE Download Manager with a setup project.
  1. In CSIEDownloadManager, add an Installer class (named IEDownloadManagerInstaller
     in this sample) to define the custom actions in the setup. The class derives from
     System.Configuration.Install.Installer. We use the custom actions to
     register/unregister the COM-visible classes in the current managed assembly when
     user installs/uninstalls the component.
          [RunInstaller(true), ComVisible(false)]
          public partial class IEDownloadManagerInstaller : Installer
              public IEDownloadManagerInstaller()
              public override void Install(System.Collections.IDictionary stateSaver)
                  RegistrationServices regsrv = new RegistrationServices();
                  if (!regsrv.RegisterAssembly(this.GetType().Assembly,
                      throw new InstallException("Failed To Register for COM");
              public override void Uninstall(System.Collections.IDictionary savedState)
                  RegistrationServices regsrv = new RegistrationServices();
                  if (!regsrv.UnregisterAssembly(this.GetType().Assembly))
                      throw new InstallException("Failed To Unregister for COM");
  2. To add a deployment project, on the File menu, point to Add, and then click
     New Project. In the Add New Project dialog box, expand the Other Project Types node,
     expand the Setup and Deployment Projects, click Visual Studio Installer, and then
     click Setup Project. In the Name box, type CSIEDownloadManagerSetup(x86). Click OK
     to create the project.

     In the Properties dialog of the setup project, make sure that the TargetPlatform
     property is set to x86. This setup project is to be deployed for 32bit IE on x86
     or x64 Windows operating systems.
     Right-click the setup project, and choose Add / Project Output .... In the
     Add Project Output Group dialog box, CSIEDownloadManager and  CSWebDownloader will  
     be displayed in the Project list. Select the Primary Output (with the Debug | Any CPU
     configuration) of them and click OK. VS will detect the dependencies of the
     CSIEDownloadManager and  CSWebDownloader, including .NET Framework 4.0 (Client Profile).
     Right-click the setup project, and choose View / Custom Actions. In the
     Custom Actions Editor, right-click the root Custom Actions node. On the Action menu,
     click Add Custom Action. In the Select Item in Project dialog box, double-click the
     Application Folder. Select Primary output from CSIEDownloadManager. This adds the
     custom actions that we defined in IEDownloadManagerInstaller of CSIEDownloadManager.
     Build the setup project. If the build succeeds, you will get a .msi file
     and a Setup.exe file. You can distribute them to your users to install or
     uninstall this IE Download Manager.
  3. To deploy the Explorer Bar for 64bit IE on a x64 operating system, you must create
     a new setup project (e.g. CSIEDownloadManagerSetup(x64) in this sample), and set its
     TargetPlatform property to x64.
     Although the TargetPlatform property is set to x64, the native shim packaged with
     the .msi file is still a 32-bit executable. The Visual Studio embeds the 32-bit
     version of InstallUtilLib.dll into the Binary table as InstallUtil. So the custom
     actions will be run in the 32-bit, which is unexpected in this code sample. To
     workaround this issue and ensure that the custom actions run in the 64-bit mode, you
     either need to import the appropriate bitness of InstallUtilLib.dll into the Binary
     table for the InstallUtil record or - if you do have or will have 32-bit managed custom
     actions add it as a new record in the Binary table and adjust the CustomAction table
     to use the 64-bit Binary table record for 64-bit managed custom actions. This blog
     article introduces how to do it manually with Orca
     In this code sample, we automate the modification of InstallUtil by using a post-build
     javascript: Fix64bitInstallUtilLib.js. You can find the script file in the
     CSIEDownloadManagerSetup(x64) project folder. To configure the script to run in the
     post-build event, you select the CSIEDownloadManagerSetup(x64) project in Solution Explorer,
     and find the PostBuildEvent property in the Properties window. Specify its value to be
          "$(ProjectDir)Fix64bitInstallUtilLib.js" "$(BuiltOuputPath)" "$(ProjectDir)"
     Repeat the rest steps in 2 to add the project output, set the custom actions, configure
     the prerequisites, and build the setup project.


To debug the ID Download Manager, you can attach to iexplorer.exe.


Implementing a Custom Download Manager

How to implement a custom download manager

IDownloadManager Interface