1. 俩个对话框，通过findwindow 获取窗口进程就行通信

1.1 服务端发送信息：

void CsendmessageDlg::OnSendCopydat()
{
    UpdateData();                                       // 更新数据
    CWnd *pWnd_resv=CWnd::FindWindow(NULL,_T("vm_copydata_test"));    //通过findwindow  查找DataRecv进程的窗口的句柄
    //HWND pWnd_resv= this->GetXHandle(L"vm_copydata_test.exe");  // 通过进程名自 获取DataRecv进程的主窗口句柄 

    if(pWnd_resv==NULL)
    {
        AfxMessageBox(L"Unable to find DataRecv.");
        return;
    }

    COPYDATASTRUCT cpd;                     // 给COPYDATASTRUCT结构赋值

    char *ch = "1234";
    cpd.dwData = 0;  //这个我也没弄懂 啥意思

    cpd.cbData =strlen(ch)+1; //防止乱码，因为strlen只计算字符串的个数，不计算最后的\0,所以这里加1
    cpd.lpData = (void*)ch;  //内容
    //AfxMessageBox();
    /**
     *   *pWnd_resv,目的窗口的句柄，
     *   WM_COPYDATA, 传递的值类型是 
     *   (WPARAM)::GetForegroundWindow(),获取当前的主窗口
     *   (LPARAM)&cpd  前面定义的结构体
     */
    ::SendMessage(*pWnd_resv, WM_COPYDATA, (WPARAM)::GetForegroundWindow(), (LPARAM)&cpd);

}

1.2 客户端接收信息 ：mfc 客户端接收信息 是通过重写wm_copydata 方法 就是下面的这个方法：具体的可以百度一下 copydata

BOOL Cvm_copydata_testDlg::OnCopyData(CWnd* pWnd, COPYDATASTRUCT* pCopyDataStruct)
{
    char *s = (char *)pCopyDataStruct->lpData;
    this->m_rec_message=s;
    //::AfxMessageBox(this->m_rec_message);

    UpdateData(FALSE);

    return CDialogEx::OnCopyData(pWnd, pCopyDataStruct);
}

2. 通过进程名获取进程的主窗口 就行通信

2.1 服务器发送信息

typedef struct tagWNDINFO  
{  
    DWORD dwProcId;  
    HWND hWnd;  
} WNDINFO, *LPWNDINFO;  
BOOL CALLBACK MyEnumProc(HWND hWnd,LPARAM lParam)  
{  
    DWORD dwProcId;  
    GetWindowThreadProcessId(hWnd, &dwProcId); //获得hWnd对应的线程ID  
LPWNDINFO pInfo = (LPWNDINFO)lParam;  
    if(dwProcId == pInfo->dwProcId) //判断是否是我们需要寻找的ID  
    {  
        pInfo->hWnd = hWnd;  
        return FALSE;  
    }  

    return TRUE;  
}  
HWND GetProcessMainWnd(DWORD dwProcId)  
{  
    WNDINFO wi;  

    wi.dwProcId = dwProcId; //被查询窗口的进程ID  
    wi.hWnd = NULL;  

    EnumWindows(MyEnumProc,(LPARAM)&wi); //枚举窗口  

    return wi.hWnd; //返回dwProcId对应的窗口句柄  
}   
HWND GetXHandle(LPCTSTR strProcessName)//procName 被调用进程名称
{
    if(NULL == strProcessName)
    {
        return false;
    }

    HANDLE handle32Snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS,0);

    if(INVALID_HANDLE_VALUE == handle32Snapshot)
    {
        return FALSE;
    }

    PROCESSENTRY32 pEntry;
    pEntry.dwSize = sizeof(PROCESSENTRY32);

    if(Process32First(handle32Snapshot,&pEntry))
    {
        bool b_Found = false;

        if(!_tcsicmp(pEntry.szExeFile,strProcessName))
        {
            b_Found = true;
        }

        while((!b_Found) && Process32Next(handle32Snapshot,&pEntry))
        {
            if(!_tcsicmp(pEntry.szExeFile,strProcessName))
            {
                b_Found = true;
            }
        }

        if(b_Found)
        {
            CloseHandle(handle32Snapshot);
            HANDLE handle  = OpenProcess(PROCESS_TERMINATE,FALSE,pEntry.th32ProcessID);
            //::MessageBox(::GetForegroundWindow(),"this->GetProcessMainWnd(pEntry.th32ProcessID);", TEXT("测试"), MB_ICONWARNING|MB_OK); 
            return this->GetProcessMainWnd(pEntry.th32ProcessID);

        }

    }
    DWORD d = GetLastError();
    CloseHandle(handle32Snapshot);

    return NULL;
}
void OnSendCopydat()
{
    UpdateData();                                       // 更新数据
    //CWnd *pWnd_resv=CWnd::FindWindow(NULL,_T("vm_copydata_test"));    //通过findwindow  查找DataRecv进程的窗口的句柄
    HWND pWnd_resv= this->GetXHandle(L"vm_copydata_test.exe");  // 通过进程名自 获取DataRecv进程的主窗口句柄 

    if(pWnd_resv==NULL)
    {
        AfxMessageBox(L"Unable to find DataRecv.");
        return;
    }

    COPYDATASTRUCT cpd;                     // 给COPYDATASTRUCT结构赋值

    char *ch = "1234";
    cpd.dwData = 0;  //这个我也没弄懂 啥意思

    cpd.cbData =strlen(ch)+1; //防止乱码，因为strlen只计算字符串的个数，不计算最后的\0,所以这里加1
    cpd.lpData = (void*)ch;  //内容
    //AfxMessageBox();
    /**
     *   *pWnd_resv,目的窗口的句柄，
     *   WM_COPYDATA, 传递的值类型是 
     *   (WPARAM)::GetForegroundWindow(),获取当前的主窗口
     *   (LPARAM)&cpd  前面定义的结构体
     */
    ::SendMessage(pWnd_resv, WM_COPYDATA, (WPARAM)::GetForegroundWindow(), (LPARAM)&cpd);

}

2.2 客户管接收信息，和上面的一样。