Hello World in COM using ATL

// mfcclientDlg.cpp : implementation file
//

#include "stdafx.h"
#include "mfcclient.h"
#include "mfcclientDlg.h"

//{----------------code added by imran -----------------

#include "..\sample1\sample1_i.c" // this is a server file
#include "..\sample1\sample1.h"   // this is a server file
//the above two server files should be 
//included in the client header file


#include "Comdef.h"       //for usage of BSTR
#include "Atlbase.h"      // for usage of CComBSTR

//----------------code added by imran -----------------}


#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CAboutDlg dialog used for App About

class CAboutDlg : public CDialog
{
public:
	CAboutDlg();

// Dialog Data
	//{{AFX_DATA(CAboutDlg)
	enum { IDD = IDD_ABOUTBOX };
	//}}AFX_DATA

	// ClassWizard generated virtual function overrides
	//{{AFX_VIRTUAL(CAboutDlg)
	protected:
	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
	//}}AFX_VIRTUAL

// Implementation
protected:
	//{{AFX_MSG(CAboutDlg)
	//}}AFX_MSG
	DECLARE_MESSAGE_MAP()
};

CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
	//{{AFX_DATA_INIT(CAboutDlg)
	//}}AFX_DATA_INIT
}

void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
	//{{AFX_DATA_MAP(CAboutDlg)
	//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
	//{{AFX_MSG_MAP(CAboutDlg)
		// No message handlers
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CMfcclientDlg dialog

CMfcclientDlg::CMfcclientDlg(CWnd* pParent /*=NULL*/)
	: CDialog(CMfcclientDlg::IDD, pParent)
{
	//{{AFX_DATA_INIT(CMfcclientDlg)
	m_edit = _T("");
	//}}AFX_DATA_INIT
	// Note that LoadIcon does not require a subsequent DestroyIcon in Win32
	m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
}

void CMfcclientDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
	//{{AFX_DATA_MAP(CMfcclientDlg)
	DDX_Text(pDX, IDC_EDIT1, m_edit);
	//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CMfcclientDlg, CDialog)
	//{{AFX_MSG_MAP(CMfcclientDlg)
	ON_WM_SYSCOMMAND()
	ON_WM_PAINT()
	ON_WM_QUERYDRAGICON()
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CMfcclientDlg message handlers

BOOL CMfcclientDlg::OnInitDialog()
{
	CDialog::OnInitDialog();

	// Add "About..." menu item to system menu.

	// IDM_ABOUTBOX must be in the system command range.
	ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
	ASSERT(IDM_ABOUTBOX < 0xF000);

	CMenu* pSysMenu = GetSystemMenu(FALSE);
	if (pSysMenu != NULL)
	{
		CString strAboutMenu;
		strAboutMenu.LoadString(IDS_ABOUTBOX);
		if (!strAboutMenu.IsEmpty())
		{
			pSysMenu->AppendMenu(MF_SEPARATOR);
			pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
		}
	}

	// Set the icon for this dialog.  The framework does this automatically
	//  when the application's main window is not a dialog
	SetIcon(m_hIcon, TRUE);			// Set big icon
	SetIcon(m_hIcon, FALSE);		// Set small icon
	
	// TODO: Add extra initialization here
	
	return TRUE;  // return TRUE  unless you set the focus to a control
}

void CMfcclientDlg::OnSysCommand(UINT nID, LPARAM lParam)
{
	if ((nID & 0xFFF0) == IDM_ABOUTBOX)
	{
		CAboutDlg dlgAbout;
		dlgAbout.DoModal();
	}
	else
	{
		CDialog::OnSysCommand(nID, lParam);
	}
}

// If you add a minimize button to your dialog, you will need the code below
//  to draw the icon.  For MFC applications using the document/view model,
//  this is automatically done for you by the framework.

void CMfcclientDlg::OnPaint() 
{
	if (IsIconic())
	{
		CPaintDC dc(this); // device context for painting

		SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);

		// Center icon in client rectangle
		int cxIcon = GetSystemMetrics(SM_CXICON);
		int cyIcon = GetSystemMetrics(SM_CYICON);
		CRect rect;
		GetClientRect(&rect);
		int x = (rect.Width() - cxIcon + 1) / 2;
		int y = (rect.Height() - cyIcon + 1) / 2;

		// Draw the icon
		dc.DrawIcon(x, y, m_hIcon);
	}
	else
	{
		CDialog::OnPaint();
	}
}

// The system calls this to obtain the cursor to display while the user drags
//  the minimized window.
HCURSOR CMfcclientDlg::OnQueryDragIcon()
{
	return (HCURSOR) m_hIcon;
}

void CMfcclientDlg::OnOK() 
{

//{-----------code added by imran on 18 sept 2k----------------------------------	
HRESULT hr = CoInitialize(NULL); // Initialize COM library

	if (FAILED(hr)) //if initialization fails then exit
	{
		AfxMessageBox("Failed to initialize COM library");
		

	}

	//get the below two constants from the servername_i.c
    const CLSID CLSID_CGreet = {0x1638ED3F,0x43E1,0x11D6,{0x89,0xB2,0x00,0x01,0x03,0x02,0x15,0x8B}};
	const IID IID_ICGreet = {0x1638ED3E,0x43E1,0x11D6,{0x89,0xB2,0x00,0x01,0x03,0x02,0x15,0x8B}};

	char  mname[20];
	CString cResult;

	//	sprintf(mname,"Imran"); <- can be used to write a string to a char array

	// ICGreet is the name of the interface in the CGreet class (which is the server)

	//pointer to the interface
	ICGreet *ptrICGreet = NULL;

	//create the com
	hr = CoCreateInstance(CLSID_CGreet,NULL,CLSCTX_INPROC_SERVER,IID_ICGreet,(LPVOID*) &ptrICGreet);

	if (SUCCEEDED(hr))
	{
		
		CComBSTR mresult;

		//get the name typed into the edit box and copy it into the char array called mname
		GetDlgItemText(IDC_EDIT1,mname,20);

		//typecast the char to a bstr before it is passed to the COM
		_bstr_t bstresult(mname);

		//finally... call the COM function via the interface pointer
		ptrICGreet->SayHello(bstresult,&mresult);
		//method signature is SayHello([in] BSTR name, [out,retval] BSTR *retstr)

	
		//copy the result into a CString so that 
		//it can be displayed in a message box
		cResult = mresult;
		MessageBox(cResult);

		//copy the result into a CString value variable associated with the edit box
		m_edit = mresult;

		//update the display on the screen
		UpdateData(FALSE);
		//free the COM pointer...
		ptrICGreet->Release();
		

	}
	//MessageBox(mname);

	CoUninitialize();
//-----------code added by imran on 18 sept 2k--------------------------------}
	
	//CDialog::OnOK();
}