freesora's computing Story

 From today, I am going to review all my studies at Dankook.
Today's topic is TCP/IP, which is the basis of network programming.

The teacher is Dr. 조경산. He is a excellent teacher =)

Basically, we need three elements, a sender, a receiver and a thing that connects between them
 so that network will work

What's the computer communication?
   : the computer, which equals with a receiver and sender or something related to computer.

 The important thing is why the computer communication has come out.
  1) Direct connection : just like word itself, it connects btw two computers directly by using a wire or physical stuff.
  2) Indirect connection : connecting all computers with a lot of networks, basically networks are connected.

 Direct connection costs a lot of money since everything would have to be closer and it also has a distance problem.

So, in order to do the indirect connection, we would have to make a rule so that all datas should have been sended and received perfectly against the direct connections.

we call the rule "protocol"

The definition of protocol is "a rule that is accepted in order to communicate between computer systems"
it consists of syntax, semantics, and timing.
syntax : the level of signal or data type.
semantics : the information for handling exceptions and each communications
timing : corresponding data speed and make an order


Now, important thing is "OSI7 layer protocol", which is a bit different from TCP/IP protocol

OSI 7 layer

Application(7)
Presentation(6)
Session(5)
Transport(4)
Network(3)
Data Link(2)
Physical(1)

However, TCP/IP has five layers.

I just started to study WinAPI... Actually, I didn't know how Windows applications work,
now I understand sort of(less than 1% though).
Below is what I've practiced.

Input, output, handling resources.


#include <windows.h>
#include "resource.h"

LRESULT CALLBACK WndProc(HWND hWnd, UINT iMessage, WPARAM wParam, LPARAM lParam);
HINSTANCE g_hInst;
LPCTSTR lpszClass=TEXT("Menu");

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpszCmdParam, int nCmdShow)
{
    HWND hWnd;
    MSG Message;
    WNDCLASS WndClass;
    g_hInst = hInstance;            // ??
    HACCEL hAccel;

    hAccel = LoadAccelerators(hInstance, MAKEINTRESOURCE(ID_TEST_MENU1));


   

    WndClass.cbClsExtra =0;
    WndClass.cbWndExtra = 0;
    WndClass.hbrBackground= CreateSolidBrush(RGB(0,0,255));
        //(HBRUSH)GetStockObject(BLACK_BRUSH);
    WndClass.hCursor = LoadCursor(NULL,IDC_ARROW);
    WndClass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
    WndClass.hInstance=hInstance;
    WndClass.lpfnWndProc = WndProc;
    WndClass.lpszClassName = lpszClass;
    WndClass.lpszMenuName=MAKEINTRESOURCE(IDR_MENU1);
    WndClass.style = CS_HREDRAW | CS_VREDRAW;
    RegisterClass(&WndClass);

    hWnd = CreateWindow(lpszClass, TEXT("Sebeom's API"), WS_OVERLAPPEDWINDOW | WS_VSCROLL,
        CW_USEDEFAULT,CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,NULL,(HMENU)NULL,hInstance,NULL);
    ShowWindow(hWnd,nCmdShow);

    while(GetMessage(&Message,NULL,0,0))
    {
        if(!TranslateAccelerator(hWnd,hAccel,&Message))
        {
            TranslateMessage(&Message);
            DispatchMessage(&Message);
        }

    }

    return (int)Message.wParam;
}


LRESULT CALLBACK WndProc(HWND hWnd, UINT iMessage, WPARAM wParam, LPARAM lParam)
{
    HDC hdc;
    PAINTSTRUCT ps;
    //static TCHAR str[256];
    static int x=100, y=100;
    static BOOL bNowDraw = FALSE;
    static int len;
    static int index = 0;
    SYSTEMTIME st;
    static TCHAR sTime[128];
    static TCHAR *storage[256] = {TEXT("Hello"), TEXT("HIHIHIHI")};
    static TCHAR str[256];

    switch(iMessage)
    {
    case WM_COMMAND:
        switch(LOWORD(wParam))
        {
            case ID_TEST_MENU1:
                MessageBox(hWnd,TEXT("First menu has beeon chosen."), TEXT("Menu Demo"), MB_OK);
            case ID_TEST_MENU2:
                lstrcpy(str, TEXT("you chose Menu 2"));
        }

    case WM_CREATE:
        SetTimer(hWnd, 1, 2000, NULL);
        SendMessage(hWnd,WM_TIMER,1,0);
        return 0;
   
    case WM_TIMER:
//        GetLocalTime(&st);
//        wsprintf(sTime, TEXT("지금 시간은 %d:%d:%d입니다"), st.wDay, st.wHour, st.wMinute);
        lstrcpy(str,*(storage+index));
        index++;
        x += 100;
        y += 100;
        InvalidateRect(hWnd,NULL,TRUE);
        return 0;

    case WM_CHAR:
        if((TCHAR)wParam == VK_BACK)
        {
            MessageBox(hWnd,TEXT("haha"),TEXT("haha"),NULL);
           
        }
        return 0;

    case WM_LBUTTONDOWN:
        x= LOWORD(lParam);
        y= HIWORD(lParam);
        bNowDraw = TRUE;
   
        return 0;

    case WM_MOUSEMOVE:
        if(bNowDraw == TRUE)
        {
            hdc = GetDC(hWnd);
            MoveToEx(hdc, x, y, NULL);
            x= LOWORD(lParam);
            y= HIWORD(lParam);           
            LineTo(hdc, x, y);
            ReleaseDC(hWnd,hdc);
        }
        return 0;

    case WM_LBUTTONUP:
        bNowDraw = FALSE;
        return 0;

    case WM_PAINT:
        hdc = BeginPaint(hWnd,&ps);
        TextOut(hdc,x,y,str,lstrlen(str));        // to display the string that I will write down.
        EndPaint(hWnd,&ps);
        return 0;
       
    case WM_DESTROY:
        PostQuitMessage(0);
        KillTimer(hWnd,1);
        return 0;

    /*case WM_LBUTTONDOWN:
        hdc=GetDC(hWnd);
        TextOut(hdc,100,100,TEXT("Beautiful Korea"), 15);
        ReleaseDC(hWnd,hdc);
        return 0;
    }*/

/*
    case WM_PAINT:
        hdc = BeginPaint(hWnd,&ps);
//        DrawText(hdc,str,-1,&rt,DT_CENTER | DT_WORDBREAK);

//        MoveToEx(hdc,300,300,NULL);
//        LineTo(hdc,400,400);
        TextOut(hdc,100,100,str,lstrlen(str));
        EndPaint(hWnd,&ps);
        return 0;
//        MessageBox(hWnd,TEXT("그대는 찹쌀 떡"),TEXT("Jegal"),MB_OK);
        //TextOut(hdc,100,100,TEXT("Seeom"),5);
        //wsprintf("Hello %d", 10);
        //EndPaint(hWnd,&ps);

        */

    }

    return(DefWindowProc(hWnd,iMessage,wParam,lParam));
    // it handles the rest of all cases like double click, quit stuff like that
}

#include "Everything.h"        // this is book's own defined header
                            // it includes windows.h etc

#define BUF_SIZE 0x200       

static VOID CatFile (HANDLE, HANDLE);        // method
int _tmain (int argc, LPTSTR argv [])
{
    HANDLE hInFile, hStdIn = GetStdHandle (STD_INPUT_HANDLE);        // make an input handler, see the return type

    HANDLE hStdOut = GetStdHandle (STD_OUTPUT_HANDLE);                // the handle where we want to write
    BOOL dashS;                       
    int iArg, iFirstFile;           

    /*    dashS will be set only if "-s" is on the command line. */
    /*    iFirstFile is the argv [] index of the first input file. */
    iFirstFile = Options (argc, argv, _T("s"), &dashS, NULL);

    if (iFirstFile == argc) { /* No files in arg list. */
        CatFile (hStdIn, hStdOut);
        return 0;
    }
   
    /* Process the input files. */
    for (iArg = iFirstFile; iArg < argc; iArg++) {
        hInFile = CreateFile (argv [iArg], GENERIC_READ,
                0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);        // Create file with
        if (hInFile == INVALID_HANDLE_VALUE) {            // if the file is not appropriate
            if (!dashS) ReportError (_T ("Cat Error: File does not exist."), 0, TRUE);
        } else {
            CatFile (hInFile, hStdOut);
            if (GetLastError() != 0 && !dashS) {
                ReportError (_T ("Cat Error: Could not process file completely."), 0, TRUE);
            }
            CloseHandle (hInFile);
        }
    }
    return 0;
}

static VOID CatFile (HANDLE hInFile, HANDLE hOutFile)
{
    DWORD nIn, nOut;                // Dword mean easily 32bit unsigned int
    BYTE buffer [BUF_SIZE];

    while (ReadFile (hInFile, buffer, BUF_SIZE, &nIn, NULL) && (nIn != 0)
            && WriteFile (hOutFile, buffer, nIn, &nOut, NULL));
    // Read the file and write exactly.
    return;
}

Easy example, take a look at the CatFile, using windows API, ReadFile and WriteFile, makes a copy of the
original file, argv[1]

LPTSTR -> Long Pointer something something, in other words, like char*