C / C++ / MFC

Need To Create a crawler/spider in vc++

20-Feb-09 2:18

Are these not the right ones?

CreateFile()
DeviceIoControl()

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

Ash_VCPP18-Feb-09 20:39

18-Feb-09 20:39

Hi All,

I have an urgent requirement to create a crawler by which i can be able to fetch data from a url, the ide should be vc++.

Thanks A Ton
Ash_VCPP

Chandrasekharan P18-Feb-09 21:06

Chandrasekharan P

18-Feb-09 21:06

very good.. now what is the problem??

CPallini18-Feb-09 21:19

CPallini

18-Feb-09 21:19

Wow, starting the working day with a smile is very good, my five.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Ash_VCPP18-Feb-09 22:14

18-Feb-09 22:14

Do you have any idea about crawler if yes then please provide me the way to start working its urgent...... Blush | :O

Thanks A Ton
Ash_VCPP

CPallini18-Feb-09 22:29

CPallini

18-Feb-09 22:29

Ash_VCPP wrote:
Do you have any idea about crawler

Yes.

Ash_VCPP wrote:
then please provide me the way to start working its urgent......

Sorry, *urgent* questions automatically falls to the bottom of the stack (just a bit above *very urgent* questions).
Smile | :)

Ash_VCPP19-Feb-09 0:18

19-Feb-09 0:18

then can you please provide me any code , guidelines or any url where i can get some useful things.......

Thanks A Ton
Ash_VCPP

Ash_VCPP18-Feb-09 22:05

18-Feb-09 22:05

I need to decide many things before starting the project,coz i am the only one responsible to make this project, so please tell me the initial guideline to start with,Like what i should use....win32 exe,win32 dll,com etc....which inter process communication logic i should use.....

Thanks A Ton
Ash_VCPP

_AnsHUMAN_ 18-Feb-09 21:32

_AnsHUMAN_

18-Feb-09 21:32

By definition:
Crawler-a person who tries to please someone in order to gain a personal advantage
Do you need it to please someone for some personal advantage?

Did you try to meet the requirements. Go get the IDE...

You need to google first, if you have "It's urgent please" mentioned in your question.
Wink | ;-)

_AnShUmAn_

Iain Clarke, Warrior Programmer

Iain Clarke, Warrior Programmer18-Feb-09 22:58

18-Feb-09 22:58

As you may have seen from your response, it's not a very good question.

1/ You haven't actually asked a question - you've just told us you have work to do. While we are, of course, very happy for you, there's not much to answer.

2/ You've got quite a bit challenge, especially if your starting from scratch.

3/ You can break it down into several challenges... Handling delays, timeouts, gettinf HTPP pages, parsing them into links, etc.

I've attached below some code I wrote years ago, grabbing a certain page from a specific URL every hour or so - an early RSS reader, essentially. It may help you with your search terms.

There are other articles on codeproject grabbing information from web pages. John Simmons wrote one recently scraping information from a codeproject page.

Good luck with your task!

Iain.

DWORD WINAPI UpdatePageThread ( LPVOID lpParameter )
{
	HWND hWnd = (HWND)lpParameter;

	DWORD dw, dwDelay = 100;
	HINTERNET	hInternet, hIConnect, hIRequest;
	BOOL	bSuccess;
	DWORD	dwStatus, dwSize, dwIndex;

	PCHAR	AcceptTypes [] = { "text/*", NULL };

	// Set up the query.
	hInternet	= NULL;
	hIConnect	= NULL;
	hIRequest	= NULL;
	hInternet = ::InternetOpen ("OC UK Notify", INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);

	if (hInternet)
		hIConnect = ::InternetConnect (hInternet, "www.overclock-uk.net", INTERNET_DEFAULT_HTTP_PORT, "user", "pass", INTERNET_SERVICE_HTTP, 0, 1);
	if (hIConnect)
	{
		hIRequest = ::HttpOpenRequest (hIConnect, NULL, "update.ocuk", NULL, NULL, (const char **)AcceptTypes,
			INTERNET_FLAG_NO_CACHE_WRITE | INTERNET_FLAG_NO_COOKIES | INTERNET_FLAG_NO_UI | INTERNET_FLAG_RELOAD | INTERNET_FLAG_NO_AUTH,
			1);
	}

	if (!hIRequest) // Raise an error?
		return 1;

	char	buf [4096];
	std::string	Page;

	while (1)
	{
		dw = WaitForSingleObject (g_hEventStop, dwDelay);
		if (dw != WAIT_TIMEOUT)
			break;
//		dwDelay = 30000; // Wait a minute before we try again.
		dwDelay = 90 * 60000; // 3/2 hours.

		bSuccess = ::HttpSendRequest (hIRequest, NULL, 0, NULL, 0);
		if (!bSuccess)
			continue; // Try again in a while.

		dwSize = sizeof (DWORD);
		dwIndex = 0;
		bSuccess = ::HttpQueryInfo (hIRequest, HTTP_QUERY_STATUS_CODE | HTTP_QUERY_FLAG_NUMBER, &dwStatus, &dwSize, &dwIndex);
		if (!bSuccess)
			continue;
		dwStatus /= 100; // Just get the 2XX part.
		if (dwStatus != 2)
			continue;

		Page.erase ();

		while (1)
		{
			memset (buf, 0, sizeof (buf));
			bSuccess = ::InternetReadFile (hIRequest, buf, sizeof (buf), &dwSize);
			if (dwSize == 0)
				break;
			if (!bSuccess)
				break;
			Page.append (buf, dwSize);
		}


		// We now have the page.
		// Process it...
//		Vec.clear ();
		int nFind = 0;
		std::string Temp;

		EnterCriticalSection (&g_CS_Updates);

		g_UpdateArray.clear ();

		// Try to update the list
		while (1)
		{
			nFind = Page.find ("<p>");
			if (nFind == std::string::npos)
				nFind = Page.find ("<p>");
			if (nFind == std::string::npos)
				break;

			Page.erase (0, nFind + 3);
			
			nFind = Page.find ("</p>");
			if (nFind == std::string::npos)
				nFind = Page.find ("</p>");
			if (nFind == std::string::npos)
				break;

			Temp = Page;
			Temp.erase (nFind, Temp.size ());

			Page.erase (0, nFind + 4);

			g_UpdateArray.push_back (Temp);
		}

		LeaveCriticalSection (&g_CS_Updates);

		PostMessage (hWnd, WM_USER + 1, 0, 0);
	}

	if (hIRequest)	::InternetCloseHandle (hIRequest);
	if (hIConnect)	::InternetCloseHandle (hIConnect);
	if (hInternet)	::InternetCloseHandle (hInternet);


	return 0;
}

Codeproject MVP for C++, I can't believe it's for my lounge posts...

Ash_VCPP19-Feb-09 0:15

19-Feb-09 0:15

Hi Iain,
Thanks for providing this important information and code, now i will try in this way and if found any difficulties then i will let you know...once again thanks for the reply..

Thanks A Ton
Ash_VCPP

Iain Clarke, Warrior Programmer

Iain Clarke, Warrior Programmer19-Feb-09 0:24

19-Feb-09 0:24

The website / page this code pointed to has long since gone, by the way!

And take the error checking with heavy skepticism...

Iain.

Codeproject MVP for C++, I can't believe it's for my lounge posts...

Sandeep Saini SRE19-Feb-09 18:58

Sandeep Saini SRE

19-Feb-09 18:58

Hi Ash,

You still need the code? If yes then please let me know.

Ash_VCPP19-Feb-09 21:05

19-Feb-09 21:05

hi sandeep,
Actually with code i also need to do some planning as i have to start the project from the scratch.....so please provide me the idea as well with the code that which way would be the better one.......

Thanks A Ton
Ash_VCPP

David Crow20-Feb-09 2:20

20-Feb-09 2:20

Ash_VCPP wrote:
I have an urgent requirement to create a crawler...

Care to define this?

Ash_VCPP20-Feb-09 2:26

20-Feb-09 2:26

i got your point till some extent but i would be pleased if you can explain it more...

Thanks A Ton
Ash_VCPP

David Crow20-Feb-09 2:27

20-Feb-09 2:27

Ash_VCPP wrote:
...i would be pleased if you can explain it more...

I believe that was the question I posed to you. The term "crawler" can take on several different meanings. What is yours?

Ash_VCPP20-Feb-09 2:30

20-Feb-09 2:30

basically i need an exe which can fetch data from any url and dump it to data base.....

Thanks A Ton
Ash_VCPP

David Crow20-Feb-09 2:34

20-Feb-09 2:34

Ash_VCPP wrote:
...fetch data from any url...

Such as URLDownloadToFile()?

Ash_VCPP20-Feb-09 2:43