# DCOM Sample: Demonstrates Remotely Calling a COM Object

The DCOM sample demonstrates how to call a COM object implemented in a Windows service from multiple clients running on different machines. It is composed of three parts:

- DrawServ — The Windows service that implements the COM object.

- ATLDraw — The client that connects to the DrawServ COM object.

- DrawCtl — A control version of ATLDraw.

Security Note
This sample code is provided to illustrate a concept and should not be used in applications or Web sites, as it may not illustrate the safest coding practices.

# Building and Running the Sample

For this sample to work, all computers must be running Windows NT 4.0 or later.

#### To build and run the sample

1. Open the solution DCOM.sln.

2. From the Build menu, click Build Solution.

3. Copy DrawServ.exe and ATLDraw.exe or DrawCtl.dll to each computer on which you want to run the sample. Register the server on each computer by running DrawServ with the command-line argument `/RegServer` or `-RegServer` (this is case-insensitive). For example:

       C:\ATL> DrawServ /RegServer

   (ATL.DLL must be registered for this to work.) You must copy the server to each client to register the CLSID for the server and the server type library on each client.

4. Start the service on the server by using the Services icon in Control Panel.

5. Using the DCOMCNFG utility on each client (run it from a command line), select the Properties of the DrawServ Class. From the Location tab, select Run application on the following computer. Enter the name of the computer on which you are running the server object.

6. Run ATLDraw and select Server Connect from the menu on each client. Draw on the client window by holding the left mouse button down and dragging a line. The drawn line should appear on each client that is connected to the same server. You can also use the View/Color menu option to change the color for each client.

The DrawServ sample will not register correctly when its path contains spaces. One solution to this problem is to edit the corresponding .rgs file and add single quotes around all occurrences of `%MODULE%`. For example, change a line containing the following:

    InprocServer32 = s %MODULE%

to the following:

    InprocServer32 = s '%MODULE%'

# Keywords

This sample uses the following keywords:

AfxMessageBox; ASSERT_VALID; ATLASSERT; AtlUnadvise; BEGIN_COM_MAP; BEGIN_CONNECTION_POINT_MAP; BEGIN_INTERFACE_MAP; BEGIN_MSG_MAP; BEGIN_OBJECT_MAP; CComCoClass; CComControl; CComModule::GetClassObject; CComModule::GetLockCount; CComModule::Init; CComModule::RegisterServer; CComModule::Term; CComModule::Unlock; CComModule::UnregisterServer; CComModule::UpdateRegistryFromResource; CComObjectRoot; CDocument::OnNewDocument; CFrameWnd::AssertValid; CFrameWnd::DockControlBar; CFrameWnd::Dump; CFrameWnd::EnableDocking; CFrameWnd::OnCreate; CFrameWnd::PreCreateWindow; CloseServiceHandle; CoCreateInstance; CoCreateInstanceEx; CoInitialize; CoInitializeSecurity; COM_INTERFACE_ENTRY; COM_INTERFACE_ENTRY_IMPL; COM_INTERFACE_ENTRY_IMPL_IID; COM_INTERFACE_ENTRY2; CONNECTION_POINT_ENTRY; ConnectSink; ControlService; CoUninitialize; CProxyIDrawServ; CreatePen; CreateService; CStatusBar::SetIndicators; CToolBar::EnableDocking; CToolBar::LoadToolBar; CView::DoPreparePrinting; CView::OnLButtonUp(nFlags, point);; CView::PreCreateWindow; CWinApp::AddDocTemplate; CWinApp::LoadStdProfileSettings; CWinApp::ParseCommandLine; CWinApp::ProcessShellCommand; CWindow::SetCapture; DECLARE_GET_CONTROLLING_UNKNOWN; DECLARE_REGISTRY_RESOURCEID; DeleteObject; DeregisterEventSource; DisableThreadLibraryCalls; Disconnect; DisconnectSink; END_COM_MAP; END_CONNECTION_POINT_MAP; END_INTERFACE_MAP; END_OBJECT_MAP; GetModuleFileName; IConnectionPointContainerImpl; IDataObjectImpl; IDispatchImpl; IMPLEMENT_DYNCREATE; Install; INTERFACE_PART; IObjectSafetyImpl; IOleControlImpl; IOleInPlaceActiveObjectImpl; IOleInPlaceObjectWindowlessImpl; IOleObjectImpl; IPersistStorageImpl; IPersistStreamInitImpl; IProvideClassInfo2Impl; IQuickActivateImpl; ISupportErrorInfo; IViewObjectExImpl; IViewObjectExImpl::Draw; LineTo; LoadString; LogEvent; MESSAGE_HANDLER; MessageBox; MoveToEx; OBJECT_ENTRY; OffsetRect; OpenSCManager; OpenService; PostThreadMessage; PtInRect; QueryInterface; RegisterEventSource; ReleaseDC; ReportEvent; SelectObject; SetCapture; SetServiceStatus; SetWindowOrgEx; StartServiceCtrlDispatcher; Uninstall